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PubMed2006

Generation of tumor-reactive effector lymphocytes using tumor RNA-introduced dendritic cells in gastric cancer patients.

Anti-tumor effector cells were generated by stimulating peripheral blood lymphocytes with cultured dendritic cells (DCs) and mRNA extracted from the gastric cancer cell line MKN45 or ascites tumor cells of gastric cancer patients. DCs were generated from an adherent fraction of peripheral blood mononuclear cells (PBMCs) in the presence of GM-CSF and IL-4. mRNA was extracted from tumor cells and subjected to T7-amplification. The DCs were electroporated (150 V/150 microF) with amplified mRNA and used after maturation with TNF-alpha to stimulate PBMCs to generate tumor RNA-introduced DC-activated killer (TRiDAK) cells. It was found that tumor RNA could efficiently be introduced into cultured DCs by electroporation (55% efficiency, 78% viability), and tumor RNA-introduced DCs could reproducibly stimulate lymphocytes to be tumor-reactive TRiDAK cells. The TRiDAK cells expressed an IFN-gamma response specific for tumor cells, but not for normal cells. Mock DCs or normal cell RNA-introduced DCs did not induce any killer cells. RNA-specific recognition of the effector cells generated was demonstrated using an amplified EGFP-mRNA system. The tumor killing activity of TRiDAK cells was inhibited not only with the anti-HLA class I antibody but also with the anti-HLA class II antibody as well as the anti-TCR antibody. TRiDAK cells reactive with autologous tumor cells could be generated in a CEA-positive gastric cancer patient with malignant ascites, in whom effector cell generation using DCs and CEA peptides had failed. These results suggest that TRiDAK cell generation is safe, feasible, and active in gastric cancer patients with malignant ascites, and is superior to other effector cell generation systems using DCs and epitope peptides. The adoptive immunotherapy of cancer using TRiDAK cells may be warranted in a clinical setting. This is the first study investigating anti-tumor effector cell generation using cultured DCs and tumor mRNA from gastric cancer cells.

Antigen-Presenting Cells↗
PubMed1991

CD4+ suppressor cells inhibit the function of effector cells of experimental autoimmune encephalomyelitis through a mechanism involving transforming growth factor-beta.

Nylon wool adherent, CD4+ T cells from the spleens of rats that have recovered from experimental autoimmune encephalomyelitis (EAE) inhibit the in vitro production of IFN-gamma, but not IL-2, by effector cells of EAE when cocultured in the presence of myelin basic protein Ag. When anti-transforming growth factor-beta (TGF-beta) antibodies are added to the co-cultures, IFN-gamma production is restored to normal levels. Irrelevant control antibodies have no effect. The same pattern of response was obtained with cells incubated in serum-free medium. In other experiments, purified TGF-beta was added to cultures of effector cells in the presence of antigen. TGF-beta inhibited the production of IFN-gamma by these cells in a dose-dependent manner, but had no apparent inhibitory effect on IL-2 production. Finally, supernatants from cultures containing effector cells and CD4+ suppressor cells plus Ag contained measurable amounts of TGF-beta, whereas supernatants from cultures of effector cells plus Ag contained no measurable amounts of TGF-beta. These results suggest that CD4+ Ts cells of EAE regulate effector cells of EAE through a mechanism that involves the secretion of TGF-beta and that the inhibitory function of this cytokine can be reversed with neutralizing antibodies directed against TGF-beta.

Animals↗
PubMed1977

Mechanism of regulation of adenylate cyclase activity in human polymorphonuclear leukocytes by calcium, guanosyl nucleotides, and positive effectors.

This study presents the results of a kinetic investigation of adenylate cyclase in human polymorphonuclear leukocytes. In the presence of a saturating concentration of substrate (1 mM), the basal activity was increased severalfold by increasing Mg2+ from 1 to 25 mM. A Hill coefficient of 1.9 was obtained for Mg2+ or ATP. The data suggest cooperative interactions between the substrate binding sites in the neutrophil adenylate cyclase complex. It has been observed that guanyl-5'-yl imidodiphosphate (Gpp(NH)p) (S0.5 = 10 MUM) significantly increased and Ca2+ (S0.5 = 0.5 MM) significantly decreased only the Vmax without affecting the Hill coefficient or S0.5 for ATP. The Hill coefficients for Ca2+ or Gpp(NH)p were 0.9 and 0.8, respectively. The Hill coefficient for Ca2+ was not changed by the increased Gpp(NH)p concentrations. It appears that neutrophil adenylate cyclase has distinct binding sites for Gpp(NH)p and Ca2+, one for each compond. The binding of ligands is not changed by the other effectors and the action is directed only toward the Vmax of the enzyme. The stimulatory action of positive effectors (prostaglandin E1, isoproterenol, histamine) was enhanced by Gpp(NH)p and depressed by Ca2+. No preferential stimulation by Gpp(NH)p nor inhibition by Ca2+ of the action of the positive effectors has been found. The data suggests that only one type of catalytic subunit responds to the action of several positive effectors. Extracellular Gpp(NH)p or Ca2+ do not affect the cyclic adenosine 3':5'-monophosphate (cAMP) level in whole neutrophils and the effect of positive effectors on cAMP production is also not significantly changed by 5 mM Ca2+ or 0.1 mM Gpp(NH)p. Ionophore A23187 in the presence of 5 mM Ca2+ enhances Ca2+ entry into cells and decreases the basal cAMP formation. It appears that Gpp(NH)p or Ca2+ act only at the intracellular site of the adenylate cyclase complex.

Adenosine Triphosphate↗
PubMed1991

Cellular models of macrophage tumoricidal effector mechanisms in vitro. Characterization of cytolytic responses to tumor necrosis factor and nitric oxide pathways in vitro.

The recently described L-arginine-dependent nitric oxide (NO) pathway has been proposed to interact synergistically with the TNF pathway in murine macrophage-mediated tumor cytotoxicity in vitro. We have employed an experimental construct in which these two pathways were independently expressed by two different effector cell populations. The TNF-dependent pathway was committed by murine 3T3 cells transfected with the cDNA encoding human pro-TNF. The NO pathway was executed by the murine EMT-6 mammary adenocarcinoma cell line treated with murine rIFN-gamma and LPS. Controls for the TNF pathway committed by the transfectant included lysis of the TNF-sensitive murine L929 cell in coculture, secretion of TNF, and absence of nitrite synthesis. For the NO pathway controls included lysis of the murine P815 mastocytoma cocultured with activated EMT-6 cells that had been pretreated with murine rIFN-gamma and LPS, production of nitrite by this activated effector cell, and an absence of TNF secretion. The target cell panel included L929, EMT-6, P815, and murine B16 melanoma and TU-5 sarcoma cell lines. All targets on this panel were susceptible to lysis by LPS-triggered murine bacillus Calmette-Guérin-activated macrophages. The 3T3 transfectant caused significant lysis of cocultured L929 and TU-5 targets. The EMT-6 effector cell only caused significant lysis of the P815 target. When both effector cells were cocultured with these target cells, lysis of the P815 target was observed to be additive or superadditive; however, for all the other targets, cytotoxicity was comparable with or subadditive compared with that seen with the 3T3 transfectant effector cell alone. Thus, these two pathways do not appear to account for the broad, potent tumoricidal activity observed for activated macrophages in vitro.

Animals↗
PubMed1991

Delayed-type hypersensitivity initiation by early-acting cells that are antigen mismatched or MHC incompatible with late-acting, delayed-type hypersensitivity effector T cells.

The elicitation of delayed-type hypersensitivity (DTH) responses in mice is mediated by the sequential activities of two different Ag-specific, Thy-1+ cells. A required early phase of elicitation is due to DTH-initiating Thy-1+ cells that are CD3- and sIg- and produce Ag-specific factors that act like IgE antibodies in that they sensitize the tissues, so that after local challenge with Ag there is release of the vasoactive amine serotonin. Released serotonin locally recruits and activates CD4+ Th-1 classical DTH effector T cells that secrete lymphokines that attract and activate a nonspecific perivascular infiltrate of circulating, bone marrow-derived leukocytes. The current study used isolated subpopulations of DTH-initiating and DTH-effector T cells to determine whether the two phases of the elicitation of DTH were entirely separate. The contact sensitivity model of DTH was used. Early-acting DTH-initiating cells, and late-acting DTH-effector T cells were either from oxazolone (OX)-immune or picryl chloride (PCl)-immune CBA or BALB/c donors and were transferred to CBA or BALB/c recipients. The results showed that DTH-initiation could be mediated by polyclonal DTH-initiating cells that were Ag mismatched or MHC incompatible with late-acting DTH effector T cells. In fact DTH-initiating cells could be both Ag mismatched and MHC incompatible with late-acting T cells. In addition, potential interactions between different cell populations were ruled out by showing that DTH-initiation could be mediated by a DTH-initiating clone that was Ag or MHC mismatched with the late-acting DTH-effector T cells. Thus, the OX-specific BALB/c clone could initiate DTH for PCl-specific CBA cells in CBA recipients if the recipients were challenged with both OX and PCl, but not when they were challenged with OX or PCl alone. We suggest, at least for the elicitation of DTH reactions in mice, that a more comprehensive description of these responses should accommodate the fact that there are early and late phase responses that each begin with Ag specificity and end with non-specific humoral factors. Inasmuch as the two Thy-1+ cells of DTH can be of different Ag specificity, this suggests that some forms of delayed and chronic inflammation, might be initiated by an immediate hypersensitivity-like immune reactivity to one set of Ag, and could be prolonged and perpetuated by delayed reactivity to another set of Ag.

Animals↗
PubMed1990

[Effective selective modification of a single-stranded fragment of DNA with alkylating derivatives of short oligodeoxyribonucleotides in the presence of reaction effectors N-(2-hydroxyethyl)phenazine derivatives of oligodeoxyribonucleotides].

Tri-, tetra-, penta- and hexanucleotides bearing a reactive 4-(N-methylamino-N-2-chloroethyl)benzylamide group can effectively and selectively modify a single-stranded DNA fragment (302 nucleotides) in the presence of effectors, N-(2-hydroxyethyl)phenazinium derivatives of oligonucleotides complementary to DNA sequences adjacent to the binding site of the reagent. The reagents investigated modify not only single-stranded but also secondary-structured DNA regions. The modification extent depends on the length of oligonucleotide parts of the reagent and effector. A gap between the two stretches associated with the target DNA prevents the effector from functioning. The substitution of an octanucleotide effector by two tetranucleotide ones only slightly reduces the modification extent with a hexanucleotide reagent. A very efficient and specific modification can be achieved by using two effectors flanking the reactive oligonucleotide derivative. The approach leads to the modification extent of up to 89% with a hexanucleotide reagent.

Alkylating Agents↗
PubMed1990

[Reactivity of oligonucleotide derivatives, containing methylphosphonate groups. VI. Increase in the effectiveness of directed action of alkylating derivatives of oligonucleotide methylphosphonate analogs on nucleic acids in the presence of effectors--3',5'-bis-N-(2-hydroxyethyl)-phenazine derivatives of oligonucleotides].

Effectors for increasing the efficiency of DNA modification with the alkylating methylphosphonate analogues of oligodeoxyribonucleotides (MFAO) were suggested. Oligodeoxyribonucleotide d(pC5A8ACAATG) used as a target DNA treated with alkylating derivatives of octathymidylate having alternating methylphosphonate and phosphodiester internucleotide bonds (both Rp- and Sp-individual diastereoisomers of MFAO were used) and bearing alkylating 4-(N-methyl-N-2-chloroethylamino)benzyl phosphoramide residue at the 3'-end. The reactions were carried out in the presence of an effector, hexadeoxyribonucleotide derivative PhnNH(CH2)2NHpCATTGTpNH(CH2)2NHPhn bearing two N-(2-hydroxyethyl)phenazinium (Phn) residues at the 3'- and 5'-ends and being complementary to the part of the target DNA neighbouring with octaadenylate. It was shown that Tm of the duplex formed by the target DNA, octathymidylate and effector is by 7-13 degrees C higher than in the absence of the effector, thus considerably increasing the efficiency of the intracomplex alkylation of the target (e.g., at 40 degrees C, the increase for the reagent based on the Rp-isomer is sixfold). Specificity of the target DNA modification by the MFAO alkylating derivatives in the presence of effector is same as with reagents based on oligodeoxyribonucleotides with natural internucleotide bonds.

Alkylating Agents↗
PubMed1990

Lymphokine-activated killer (LAK) cells. IV. Characterization of murine LAK effector subpopulations.

The precursors of murine lymphokine-activated killers (LAK) can be divided into two major subsets: NK-like (CD8-, NK1.1+, asialo GM1+) and T-like (CD8+, NK1.1-, asialo GM1+). LAK effectors have generally been characterized as being either CD8+ or NK1.1+. In this study, we divided each of these effector subsets further by virtue of their expression of B220 (as defined by the mAb 6B2) and Ly-24 (Pgp-1). Freshly obtained CD8+ and NK1.1+ cells were found, by fluorescence analysis, to be B220-. Lytically active LAK effector subsets were either CD8+ B220+ Ly-24+ or NK1.1+ B220+ Ly-24+. Most interestingly, a distinct NK1.1+ B220- Ly-24+ subset existed but had minimal lytic activity, suggesting that only a subset of NK cells is capable of acquiring the broad lytic activity of LAK. The acquisition of the B220 marker by the CD8+ subset closely paralleled its expression of lytic activity. However, classical MHC-restricted CD8+ CTL were Ly-24+ but remained B220- suggesting that the acquisition of the B220 marker, as defined by the 6B2 mAb, is not merely the result of cellular differentiation but may serve as a marker of MHC-nonrestricted killers. Three "classes" of target cells were examined for their susceptibility to lysis by the LAK effector subsets: YAC-1 (NK sensitive), CL27A (NK resistant), and autologous lymphoblasts that have been modified with 2, 4, 6-trinitrobenzene sulfonic acid. YAC-1 was lysed exclusively by the NK1.1+ B220+ Ly-24+ subset, 2,4,6-trinitrobenzene sulfonic acid-self was lysed exclusively by the CD8+ B220+ Ly-24+ subset whereas CL27A was lysed by both subsets. This pattern of lysis was confirmed by the in vivo depletion of NK1.1+ cells. It, therefore, appears that LAK effector subsets may be more selective in their lytic repertoire than previously thought.

Animals↗
PubMed1990

Sensitivity of ovarian tumor cells to effector cells generated by various biological response modifiers.

The sensitivity of freshly derived human ovarian tumors (FOT) to various allogeneic cytotoxic effector cells stimulated by recombinant interleukin 2 (rIL-2), recombinant interferon alpha 2 (rIFN-alpha 2), OK-432, and concanavalin A was examined using the 51Cr release assay. Peripheral blood lymphocytes (PBL) of normal female donors were used as source of effector cells. Incubation of PBL with these biological response modifiers for 24 h generated effector cells with high natural killer activity, and only 20% (1/5) of the FOT examined were susceptible to lysis. By contrast, 83% (5/6) of the FOT were sensitive to lymphokine-activated killer (LAK) cells generated by rIL-2. OK-432 and concanavalin A activation of PBL also generated cytotoxic cells, though the cytotoxic activity against FOT was much less than that obtained by LAK cells. The addition of OK-432 to LAK culture medium containing rIL-2 generated effector cells with higher cytotoxicity against FOT than cultures with IL-2 alone. However, the addition of rIFN-alpha 2 in LAK culture medium resulted in the generation of effector cells with lower cytotoxicity. The addition of rIL-2, rIFN-alpha 2, or OK-432 to LAK cells during the in vitro cytotoxicity assay had no significant effect. When FOT target cells were pretreated with OK-432 they became more sensitive to LAK than nontreated tumor cells. However, pretreatment with rIL-2 or rIFN-alpha 2 did not influence cytolysis. These results suggest that the generation of LAK cells in vitro using rIL-2 plus OK-432 may be a more effective way to prepare these cells for adoptive immunotherapy in the treatment of ovarian cancer.

Concanavalin A↗
PubMed1990

Effect of heat treatment on tumor cells and antitumor effector cells.

We examined the effects of heat treatment on tumor cells and antitumor effector cells in order to investigate the combined effects of hyperthermia and immunotherapy including adoptive immunotherapy. Plasmacytoma MOPC104E syngeneic to BALB/c mice was used as the tumor cell line, while fresh spleen cells immunized to MOPC104E (IM-FSC) and interleukin-2-cultured lymphocytes induced in vitro from IM-FSC (CL) were used as the effector cells. Tumor cells or effector cells were heat-treated in a water bath at 42 degrees C for 30 or 60 min. Tumor cells heat-treated at 42 degrees C for 30 min grew temporarily and then regressed in the tumor transfer test, whereas untreated tumor cells showed no regression under any conditions. Furthermore, fresh spleen cells of mice inoculated with heat-treated tumor cells from regressed tumors showed marked tumor-neutralizing activity. The antitumor effects of CL were markedly inhibited by heat treatment according to the results of the tumor-neutralizing test and the 51Cr release assay, whereas heat treatment had little influence on the antitumor activity of IM-FSC. However, the neutralizing activity of effectors and the killing activity of CL against heat-treated tumor cells were both markedly augmented, since the susceptibility of the tumor cells to the antitumor effector cells was augmented by heat treatment. These results suggest that heat treatment of tumor cells augments the antitumor effects of IM-FSC and CL, hence we speculate that hyperthermia augments the effects of immunotherapy including adoptive immunotherapy.

Animals↗
PubMed1985

Lysis of human cytomegalovirus infected fibroblasts by natural killer cells: demonstration of an interferon-independent component requiring expression of early viral proteins and characterization of effector cells.

We investigated the susceptibility of cells infected with human cytomegalovirus (HCMV) to lysis by human natural killer (NK) cells, examining in particular its relationship to sequential viral protein expression, interferon (IFN), and the nature of the effector cells. HCMV-infected fibroblasts were lysed by peripheral blood mononuclear cells from normal seronegative individuals. The effector cells were large granular lymphocytes of Leu-7+, Leu-11+, and to a lesser extent Leu-7- phenotype. Depletion studies suggested they were the same population of NK cells that lyse uninfected fibroblasts, but a subset of NK cells that lyse K562 cells. HCMV-infected cells treated with phosphonoformate and cells infected for 16 hr that only express the nonstructural HCMV immediate early and early proteins and not the late (structural) proteins were susceptible to lysis by IFN-pretreated effector cells, whereas cells expressing immediate early antigens alone were not. This enhanced susceptibility to lysis was associated with increased effector:target binding in target cell binding assays, and was competitively inhibited by uninfected fibroblasts in cold target competition assays. It was independent of IFN release from the infected target cells or effector cells. These results suggest that the increased susceptibility to lysis by NK cells produced by a human herpes virus HCMV i) is manifest when early viral proteins are expressed, ii) is related to enhanced expression of a target structure likely to be present on uninfected fibroblasts, and iii) has a major component that is independent of IFN.

Adult↗
PubMed1985

Murine interstitial nephritis. IV. Long-term cultured L3T4+ T cell lines transfer delayed expression of disease as I-A-restricted inducers of the effector T cell repertoire.

In the present study we observed that long-term cultures of tubular antigen-reactive L3T4+ T cells from immune SJL mice are able to adoptively transfer interstitial nephritis by 12 wk after i.v. injection. Lesions that develop under these conditions generally occur in the absence of anti-tubular basement membrane antibody formation. These cultured T cell lines are I-A restricted, require L3T4-associative interactions, and are tubular antigen specific, but do not share the phenotype, function, or H-2-restriction characteristics of Lyt-2+ nephritogenic effector T lymphocytes. Rather, our L3T4+ T cell lines, and phenotypically similar lymphocytes harvested from renal infiltrates, are inducers of this Lyt-2+ effector T cell repertoire. Such effector T cells, typically found in immune lymph nodes 4 to 7 days after immunization, can be induced in vitro within 5 days and will acutely transfer disease within another 5 days when placed under the kidney capsule. These findings collectively indicate that the time course for optimal effector cell differentiation and potential expression is relatively short. The immunologic inertia we previously observed between immunization or i.v. adoptive transfer and the development of cellular lesions, therefore, seems to reside in other systemic or interactional events beyond the timely formation of effector T cells.

Animals↗
PubMed1986

Differential helper and effector responses of Lyt-2+ T cells to H-2Kb mutant (Kbm) determinants and the appearance of thymic influence on anti-Kbm CTL responsiveness.

The goal of this study was to assess and compare the allorecognition requirements for eliciting Lyt-2+ helper and effector functions from primary T cell populations. By using interleukin 2 (IL 2) secretion as a measure of T helper (Th) function, and cytolytic T lymphocyte (CTL) generation as a measure of effector function, this study compared the responses of Lyt-2+ T cells from wild-type B6 mice against a series of H-2Kb mutant determinants. Although all Kbm determinants stimulated B6 Lyt-2+ T cells to become cytolytic effector cells, the various Kbm determinants differed dramatically in their ability to stimulate Lyt-2+ T cells to function as IL 2-secreting helper cells. For example, in contrast to Kbm1 determinants that stimulated both helper and effector functions, Kbm6 determinants only stimulated B6 Lyt-2+ T cells to become cytolytic and failed to stimulate them to secrete IL 2. The distinct functional responses of Lyt-2+ T cells to Kbm6 determinants was documented by precursor frequency determinations, and was not due to an inability of the Kbm6 molecule to stimulate Lyt-2+ Th cells to secrete IL 2. Rather, it was the specific recognition and response of Lyt-2+ T cells to novel mutant epitopes on the Kbm6 molecule that was defective, such that anti-Kbm6 Lyt-2+ T cells only functioned as CTL effectors and did not function as IL 2-secreting Th cells. The failure of Lyt-2+ anti-Kbm6 T cells to function as IL 2-secreting Th cells was a characteristic of all Lyt-2+ T cell populations examined in which the response to novel mutant epitopes could be distinguished from the response to other epitopes expressed on the Kbm6 molecule. The absence of significant numbers of anti-Kbm6 Th cells in Lyt-2+ T cell populations was examined for its functional consequences on anti-Kbm6 CTL responsiveness. It was found that primary anti-Kbm6 CTL responses could be readily generated in vitro, but unlike responses to most class I alloantigens that can be mediated by Lyt-2+ Th cells, anti-Kbm6 CTL responses were strictly dependent upon self-Ia-restricted L3T4+ Th cells. Because the restriction specificity of L3T4+ Th cells is determined by the thymus, in which their precursors had differentiated, anti-Kbm6 CTL responsiveness, unlike responsiveness to most class I alloantigens, was significantly influenced by the Ia phenotype of the thymus in which the responder cells had differentiated.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Natural cytotoxicity against mouse hepatitis virus-infected cells. II. A cytotoxic effector cell with a B lymphocyte phenotype.

The effector cell in mouse spleen which mediates natural cytotoxicity against mouse hepatitis virus (MHV)-infected target cells was characterized. The target cells were MHV-infected BALB/c 3T3, and the assay time was 3 hr. The effector cell, designated virus killer (VK) cell for the purpose of discussion, had the following phenotype: lymphocyte morphology, plastic-nonadherent, nylon wool-adherent, nonphagocytic, cyclophosphamide-sensitive; by antibody plus complement (C) depletion studies, it was asialo GM1-, NK 1.2 alloantigen-negative, Thy-1.2-, Lyt-5-, and macrophage antigen-negative; by rosetting techniques, it was Fc receptor-positive and surface Fab+; by flow cytometry (FACS) analysis, it was Lyt-2-, MAC-1-, Ia+, IgG (gamma)+, IgM (mu)+, IgD (delta)+, and B cell lineage antibody B-220+. NK cells, measured for cytotoxicity on YAC-1 cells, were similarly tested and were found to differ from the VK cell in the following properties: nylon wool-nonadherent, asialo GM1+, NK alloantigen-positive, Lyt-5+, surface Fab-, MAC-1+, Ia-, IgG-, IgM-, IgD-, and B-220-. The VK effector cell had a phenotype highly distinguishable from NK cells, effectors most commonly associated with antiviral natural cytotoxicity. The VK cell had a phenotype identical to that of a B lymphocyte and was identified as such. Although the effector cells displayed cell surface antibody, the antibody did not appear to be involved in lysis, because lysis could not be blocked by F(ab)'2 directed against Fab, mu, or delta. Cytotoxicity was more likely associated with recognition of the B lymphocyte surface by the MHV glycoprotein E2, as shown in the accompanying companion paper. This is the first demonstration that natural cytotoxicity can be mediated by B lymphocytes.

Animals↗
PubMed1986

Demonstration of NK cell-mediated lysis of varicella-zoster virus (VZV)-infected cells: characterization of the effector cells.

Infection with varicella-zoster virus (VZV) rendered RAJI cells more susceptible to lysis by non-adherent blood lymphocytes. At an effector to target ratio of 80:1 the mean percentage of 51Cr release of VZV-infected RAJI cells was 41 +/- 12%, whereas that of uninfected RAJI cells was 15 +/- 6%. The increased susceptibility to lysis was associated with increased effector to target conjugate formation in immunofluorescence binding assays. The effector cells cytotoxic for VZV-infected RAJI cells were predominantly Leu-11a+ Leu-4- granular lymphocytes as demonstrated by fluorescence-activated cell sorting. The effector cell active against VZV-infected RAJI cells appeared similar to those active against herpes simplex virus (HSV)-infected cells, because in cold target competition experiments the lysis of 51Cr-labeled VZV-infected RAJI cells was efficiently inhibited by either unlabeled VZV-infected RAJI cells (mean 71% inhibition, 2:1 ratio unlabeled to labeled target) or HSV-infected RAJI cells (mean 69% inhibition) but not by uninfected RAJI cells (mean 10% inhibition). In contrast, competition experiments revealed donor heterogeneity in the overlap between effector cells for VZV- or HSV-infected RAJI vs K-562 cells.

Adult↗
PubMed1979

Deficiency of antibody-dependent cellular cytotoxicity and mitogen-induced cellular cytotoxicity effector cell function in patients with acute myelogenous leukemia in remission.

Patients with acute myelogenous leukemia in remission have pronounced deficiency in antibody-dependent cellular cytotoxicity (ADCC) and mitogen-induced cellular cytotoxicity. The deficiency in ADCC was partly explained by reduction in the number of circulating effector cells (Fc receptor-bearing cells) demonstrable at a time when white blood cell and platelet counts were normal. These cytotoxic functions, as well as the circulating numbers of T-cells and Fc receptor-bearing cells were further decreased by the administration of monthly cycles of combination chemotherapy with 1-beta-D-arabinofuranosylcytosine and 6-thioguanine. Following each cycle of chemotherapy, progressive recovery of these functions occurs during the third and fourth weeks with occasional increases above base line in patients in whom chemotherapy is withheld for longer than five weeks. In selected patients recovery of one cytotoxic function preceded the other, indicating that these functions are mediated by different effector cells. Administration of a single dose of daunomycin i.v. had no effect in either of these cytotoxic functions or in the circulating numbers of lymphocytes. The decrease in ADCC effector cell function induced by phase cycle-specific agents correlated with the level of reactivity exhibited by patients after achieving bone marrow and clinical remission. Patients showing low levels of reactivity postremission experienced highest degree of depression. In two patients, complete abrogation of ADCC effector function was demonstrated with minimal recovery even six weeks after stopping chemotherapy. These findings indicate that effector cells in ADCC and mitogen-induced cellular cytotoxicity are highly susceptible to phase cycle-specific agents, and their recovery takes longer that of other lymphoid and nonlymphoid populations.

Adult↗
PubMed1985

Suppression in Xenopus laevis: thymus inducer, spleen effector cells.

Studies were carried out on suppressor function in the amphibian Xenopus laevis, the South African clawed toad. Suppression by the thymus of haemagglutinin (HA) production by spleen is antigen-dependent, partially specific and not MHC-restricted in this species (Ruben, Buenafe & Seivert, 1983). Three questions were considered in this study. Does the thymus effect suppression by stimulating peripheralized spleen effector cells, or do effector cells reside within the thymus? Do macrophages participate in the induction and/or expression of thymus-dependent suppressor function? Can thymus suppressor and helper functions be distinguished by using irradiation treatment? The capacity of immunized thymus to suppress HA when co-cultured with spleen fragments from immunized, cyclophosphamide (CyP)-injected animals was tested. Immunized thymus failed to suppress the high levels of HA production by spleen fragments from CyP-treated, immunized donors. Colloidal carbon injection resulted in blockade of macrophage function, and both the capacity of thymuses to suppress and of spleens to be suppressed in co-cultures. Finally, the effect of thymus exposure to gamma-irradiation in vitro was tested using autogeneic thymus/spleen combinations. This enabled the visualization of thymic helper function, which is MHC-restricted in Xenopus (Bernard et al., 1981). Four dosages of irradiation were tested after antigen challenge. The highest HA titres were produced by spleen co-cultures with thymuses which had received 1000 rads. We conclude that suppression of HA production in spleen is not the result of thymus suppressor effector cells, but that suppressor function is mediated by thymus inducer cells which stimulate suppressor effectors in spleen. Both the thymic inducers and effectors in the spleen are sensitive to CyP and macrophage blockade. Our studies further suggest that we are able to distinguish between the thymic functions of help and suppression in Xenopus by taking advantage of their differential sensitivities to irradiation. While it has been postulated, on other grounds, that suppression was one of the earliest thymic regulatory functions to have evolved (L.N. Ruben & R.H. Clothier, submitted), here we suggest the presence of sequential activities of more than one cellular subset, as early in evolution as the primitive anuran (tail-less) amphibia.

Animals↗
PubMed1988

Induction of natural killer effectors from human thymus with recombinant IL-2.

The NKH1 Ag is expressed on all cells in human peripheral blood capable of mediating spontaneous non-MHC restricted cytolytic function (i.e., natural killing). The majority of NK cells do not express CD3 Ag and do not express TCR gene products. However, approximately 20 to 25% of NKH1+ cells coexpress CD3 and TCR proteins. Both NKH1+CD3+ and NKH1+CD3- effectors can proliferate in response to IL-2 which also results in enhancement of cytolytic function. In the present studies, we examined thymocytes after incubation with rIL-2 for the presence of NKH1+ cells and for the development of non-MHC restricted cytolytic function. NKH1+ cells and NK activity could not be detected in fresh thymus. After culture with rIL-2 only, NK activity appeared in 3 days, reached a maximum after 7 days, and was effective against a panel of NK-sensitive targets. NK activity was correlated with the expression of NKH1 on the surface of in vitro proliferating thymocytes and immunofluorescent cell sorting demonstrated that almost all cytolytic activity was mediated by NKH1+ cells. As expected given the thymic origin of these cells, the majority of NKH1+ cells in culture expressed CD3. However, all cultures contained NKH1+CD3- effector cells which represent 15 to 40% of the NKH1+ population. As in peripheral blood, both NKH1+CD3- and NKH1+CD3+ exhibited non-MHC-restricted cytotoxicity, but only CD3+ effectors could be inhibited by anti-T3 mAb. These findings demonstrate that rIL-2 alone can induce subpopulations of thymocytes to proliferate, to express the NKH1 marker and become NK active in vitro. Furthermore, they suggest that the thymus which plays a role in the differentiation of NKH1+CD3+ NK effectors may also play a role in the differentiation or maturation of NKH1+CD3- NK effectors.

Antigens, Differentiation↗