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At least 19 recordsLinked to original sources
PubMed1977

Surface antigen changes accompanying lymphocyte activation. Selective reactivity of certain anti-H-2 antisera with activated lymphocytes of unrelated H-2 haplotype.

It is here shown that some noncongenic anti-H-2 antisera produced by using normal spleen cells at the immunogen can contain cytotoxic antibody activity against activated, but not resting, lymphocytes of unrelated H-2 haplotype strains. Reactivity was noted against lymphocytes activated in vitro with T- or B-cell mitogens, or in vivo by antigenic stimulation. Analysis of the results indicated that the anti-activated lymphocyte activity was most likely related to production of anti-Ala-1 ('activated lymphocyte antigen') alloantibodies. This appears to occur as a result of donor lymphocyte activation during production of the anti-H-2 antisera, using Ala-1-incompatible donor and recipient combinations, where the donor cells are competent to recognize and react against host H-2 incompatibilities. These results confirm the finding that lymphocyte activation can be accompanied by the expression of an antigen that is either absent or weakly expressed on resting lymphocytes.

Animals↗
PubMed1990

Combination of mutant EL-4 thymoma cells and EBV-infection in B lymphocyte activation a) EBV-infection of EL-4-activated lymphocytes. b) Use of EL-4 cells as feeders for lymphoblastoid cell lines.

The combination of mutant EL-4 thymoma cells and Epstein-Barr virus (EBV)-infection in the activation of human B lymphocytes was studied with two approaches: a) limiting numbers of B cells were first activated by EL-4 contact in order to expand the B cell population and then infected with EBV. Results show that EBV could induce further Ig synthesis, although was unable to determine proliferation or to generate immortalized lines from EL-4 activated cells. b) EL-4 cells were compared to conventional PBM as feeders for cultures of established lymphoblastoid cell lines (LCL) at low cell densities. EL-4 feeder activity was strictly dependent on the presence of phorbol-myristate-acetate (PMA) and supernatant from stimulated T-lymphocytes (T-SN). EL-4 feeders induced earlier proliferation peak and greater Ig synthesis by LCL. The latter effect could be also mediated by the addition of PMA and T-SN, even if a cooperating cell-to-cell signal by PMA and T-SN-sensitized-EL-4 cells could not be excluded. Altogether results indicate that EL-4 cells do not represent a clear advantage over classic PBM as feeders for cultures of established LCL at low cell densities.

B-Lymphocytes↗
PubMed1992

Increased surface expression of a newly identified 150-kDa dimer early after human T lymphocyte activation.

Lymphocyte activation induces or increases the expression of several surface structures, some of which are directly involved in cell growth such as receptors for IL-2 or transferrin. In order to identify new structures characteristic of activated lymphocytes, we developed a series of mAb against functionally defined human T cell clones. In the present study we report the isolation of a mAb termed BB18 recognizing, at the cell surface, a novel 150-kDa glycoprotein dimer whose expression on T lymphocytes increases readily after their activation with various stimuli including lectins. In contrast, in the presence of PMA, cell-surface expression of this 150-kDa structure is down-regulated even earlier than CD3 molecules. Biochemical studies as well as phenotypic analysis revealed that this structure is different from all previously identified molecules on the lymphocyte cell surface. Furthermore, functional studies showed that triggering this disulfide-linked dimer through BB18 epitope in the presence of submitogenic concentrations of PMA induced strong lymphocyte proliferation. This proliferative response require E+ cells and accessory cells, and this even after immobilization of BB18 mAb.

Animals↗
PubMed2001

Cascades of transcriptional induction during human lymphocyte activation.

Lymphocyte activation is known to be associated with the induction of genes implicated in cytokine signaling and cellular proliferation. High-density microarrays offer the means to monitor global cellular expression profiles, temporal relationships between classes of transcripts, and alterations associated with human disease or immunosuppression. We sought to determine whether microarray analysis would accurately reflect the normal pattern of gene expression following human T cell activation, and whether the complex expression patterns identified could be analyzed to produce a functional profile of lymphocyte activation. We examined a time course of sequential expression profiles for 6,800 cellular transcripts in human lymphocytes activated with concanavalin A. Expression patterns were grouped using clustering analysis and validated using Northern blotting. Genes known to be induced following T cell activation were accurately identified, and the qualitative patterns of gene expression were well correlated between Northern and microarray analyses. Quantitative differences in gene expression levels were less well correlated between these two techniques. Expression profile analysis revealed the sequential induction of groups of functionally similar genes, whose temporal coregulation underscores known cellular events during T cell activation. This functional "fingerprint" of lymphocyte activation may prove useful for comparisons of lymphocyte responses under experimental conditions and in disease states.

Cluster Analysis↗
PubMedDate not supplied

Nursing care of patients receiving activated lymphocytes.

Activated lymphocytes are administered to patients as a component of many biological therapy clinical trials. Oncology nurses caring for these patients need to understand administration techniques, potential side effects, and management strategies. Activated lymphocytes may be administered intravenously or regionally; administration techniques and side effects differ depending on the route of administration. The major side effects with intravenous infusion are chills/rigors, fever, hypotension, tachycardia, respiratory compromise, headache, nausea, and vomiting. When activated lymphocytes are infused regionally, the most common side effects are immediate regional discomfort and delayed chills, fever, and hypotension. Management of these side effects involves intense nursing care including assessment, monitoring, and interventions to promote medical stability and symptom control. Astute assessment skills and sound nursing judgement are essential for the safe administration of activated lymphocytes.

Humans↗
PubMed1979

The biochemistry and in vitro activity of soluble factors of activated lymphocytes.

Activated lymphocytes release numerous products which are either synthesized de novo or in increased amounts; some of these products play a role in the regulation of the immune response and are designated as mediators of cellular immune reactions or lymphokines. The first lymphokine described was the macrophage migration inhibitory factor (MIF) which has been studied most extensively with regard to its chemical and biological properties. Using sensitive radiolabelling techniques and an antiserum against highly purified fractions of MIF we were able to identify several products of activated guinea pig lymphocytes with different molecular weights of 15.000, 30.000, 45.000, 60.000 which all had an isoelectric point of 5.2 and were all inhibitory to macrophage migration. It is suggested, that these molecules are oligomers of a common subunit of molecular weight 15.000. It was further shown, that molecules of the same physical-chemical and serological characteristics are produced by activated B-cells, L2C leukemia cells and growing fibroblasts, thus further substantiating earlier reports on the production of MIF by lymphoid and non-lymphoid cells. The described molecules were also shown not to contain determinants of the major histocompatibility complex and to be distinct from lymphotoxin, another lymphocyte activation product. It is concluded, that MIF is not a single molecule but rather a system of structurally related molecules. Their interaction with macrophages and possible relationships to macrophage activating factor is discussed.

Animals↗
PubMed1990

Identification and gene cloning of a new phosphatidylinositol-linked antigen expressed on mature lymphocytes. Down-regulation by lymphocyte activation.

Lymphocytes are shown to express a limited number of a unique category of membrane Ag, such as Thy-1, Ly-6, Ly-31, and Qa-2, that are covalently linked to the membrane phosphatidylinositol (PI). We have identified a new glycosyl-phosphatidylinositol (GPI)-anchored lymphocyte Ag, B7, by using a mAb and have determined the primary structure by cDNA cloning. B7 Ag was expressed on the majority, if not all, of the mature lymphocytes of both T and B lineages, including strongly CD3+ thymocytes, most splenic T cells, and approximately 60% of splenic IgM+ B cells, whereas the expression of B7 Ag on bone marrow cells was negligible. The expression of B7 Ag was nearly completely abolished with as little as 2 mU of PI-specific phospholipase C per ml, which did not completely eliminate Ly-6C and Thy-1 expression. Unlike the expression of other GPI-linked lymphocyte Ag, the expression of B7 was rapidly down-regulated upon the activation of T cells by mitogens or IL-2 both in vitro and in vivo. Immunoprecipitation analysis revealed that B7 Ag was an approximately 12-kDa protein. With a CDM8 expression vector, a cDNA encoding B7 Ag was cloned, and it was confirmed that the B7 Ag on cDNA-transfected cells was indeed PI-specific phospholipase C sensitive. The B7 cDNA contained an open reading frame of 222 bp including a typical N-terminal leader sequence and a characteristic sequence at the C terminus encoding hydrophobic amino acids. A computer search revealed no significant homology to any known molecule at both DNA and amino acid sequence levels. Northern blot analysis indicated that the B7 transcript was expressed on lymphohematopoietic tissues, including thymus, spleen, and bone marrow, but not on other organs, such as liver, kidney, and brain. The results indicated that B7 Ag is a new member of the GPI-anchored proteins which is selectively expressed on mature resting but not activated lymphocytes.

Amino Acid Sequence↗
PubMed1982

Neutrophil product with lymphocyte activating factor activity.

Lymphocyte activating factor (LAF) is a monocyte derived product which has the ability to enhance the proliferative response of murine thymocytes to the T cell mitogen concanavalin A (Con A). In this report, we have demonstrated that supernatants from normal human polymorphonuclear cells (PMNs) and from granules obtained from PMNs exhibit activity identical to LAF when tested against mouse thymocytes. Our results suggest that PMNs may release factors essential for T cell activation and thus, like monocytes, may serve as important accessory cells in the development of T cell-dependent immunity.

Animals↗
PubMed1982

Ultrastructural localization of adenosine triphosphatase activity in lymphocytes activated in vitro by phytohaemagglutinin.

The ultrastructural localization of Ca2+, Mg2+-activated ATPase was studied in phytohaemagglutinin activated lymphocytes and in normal unstimulated lymphocytes. Cells, fixed in paraformaldehyde--glutaraldehyde, were incubated in a medium containing 3 mM ATP, 5 mM CaCl2 and 2.4 mM Pb(NO3)2 in 0.1 M tris buffer at pH 8.5, the optimum pH for histochemical demonstration of this enzyme. Reaction product was localized in the endoplasmic reticulum, nuclear membrane, Golgi apparatus and mitochondria and on the membrane surrounding large electron-dense bodies. Cytoplasmic vesicles and the plasma membrane were negative. Activity in unstimulated lymphocytes showed a similar localization but the amount of endoplasmic reticulum was much less than in activated lymphocytes. The pH of the medium was critical for the localization of the enzyme. At pH 7.5, the cytoplasmic reaction was almost completely inhibited but a dense precipitate was present on the outer surface of the plasma membrane. The reaction was stimulated by either Ca2+ or Mg2+ and was greatly decreased in the absence of these cations or in the presence of p-chloromercuribenzoate or N-ethylmaleimide. Oligomycin inhibited selectively the reaction in mitochondria but not the reaction at other sites. While the reaction in mitochondria showed complete substrate specificity, a mild reaction was obtained at the other sites with uridine diphosphate or sodium beta-glycophosphate as substrate. ATP was, however, the preferential substrate.

Calcium-Transporting ATPases↗
PubMed2000

Immunotoxicity of N,N-diethylaniline in mice: effect on natural killer activity, cytotoxic T lymphocyte activity, lymphocyte proliferation response and cellular components of the spleen.

We previously found that N,N-diethylaniline increased the frequency of sister chromatid exchange (SCE) of human lymphocytes to about five times that of the control value, and was as toxic as cyclophosphamide used as a positive control for SCE. To explore whether N,N-diethylaniline affects the function of lymphocytes, we evaluated its immunotoxicity using CBA/N mice. The mice were divided into four groups and received 0, 100, 200, or 400 mg/kg body weight of N,N-diethylaniline by subcutaneous injection. The following items were investigated on days 3 and 7 after injection: body weight, weight of spleen, number of splenocytes, natural killer (NK) and cytotoxic T lymphocyte (CTL) activities, and concanavalin A (Con A)- and lipopolysaccharide (LPS)-stimulated lymphocyte proliferation using splenocytes. The following splenocyte phenotypes were also quantified by flow cytometry: (1) B cells; (2) total T cells; (3) CD4(+) and CD8(+) T cells; (4) NK; (5) macrophages and (6) nucleated erythrocytes. The splenic NK and CTL activities in exposed groups significantly decreased compared to the control in a dose-dependent manner and lymphocytes from the 200 and 400 mg/kg groups showed significantly higher spontaneous proliferation. The weight of the spleen and number of splenocytes were significantly higher in exposed groups than in the control. N,N-Diethylaniline also increased the percentages of macrophages, nucleated erythrocytes and B cells in the spleen. On the other hand, N,N-diethylaniline did not affect LPS-stimulated B cell and Con A-stimulated T cell proliferation, or the percentages of NK, total T, and CD4(+) and CD8(+) T cells in the spleen or the body weight of mice. The above findings indicated that N,N-diethylaniline selectively inhibited splenic NK and CTL activity and this inhibition was due to decreased NK and CTL functions, but not due to changes in the numbers of splenic NK and T cells.

Aniline Compounds↗
PubMed1979

Virus plaque assay: effective detection of virus plaque forming cells at the early stage of lymphocyte activation by mitogen and alloantigen.

Activated lymphocytes were detected quantitatively by virus plaque assay (VPA) during the course of lymphocyte cultures stimulated by mitogen or alloantigen. In Con A-stimulated cultures, the number of virus-plaque forming cells (V--PFC) was a more sensitive method of detecting the early stage of lymphocyte activation than [3H]-thymidine (3H-TdR) incorporation. This evidence was obtained by two methods of collecting cells of each stage. First, when Con A-activated lymphocytes were fractionated by velocity sedimentation at unit gravity to separate cell populations according to each cell stage, the ratio of the number of V-PFC to the radioactivity of incorporated [3H]-TdR was larger in the earlier stage of cell cycle than in the later stage. Second, when cultured lymphocytes were synchronized directly by addition of excess thymidine and colchicine, similar results were obtained. In primary mixed lymphocyte cultures, the generation of cytotoxic lymphocytes (CTL) was correlated better with the proliferative response than with V-PFC production. It was also found that both the incorporation of [3H]-TdR and the generation of CTL were abrogated by cytosine arabinoside (Ara-C) added to cultures up to one day before assay, whilst the generation of V-PFC was not so markedly affected by Ara-C. These findings suggest that V-PFC represent the number of precursor cells which require one or more generations to differentiate to CTL and not simply the number of effector lymphoyctes already exhibiting cytotoxicity.

Animals↗
PubMed1999

A comparison of the expression of lymphocyte activation markers in blood, bronchial biopsies and bronchoalveolar lavage: evidence for an enrichment of activated T lymphocytes in the bronchoalveolar space.

In this study healthy never-smoking subjects (n = 18) were recruited from a population study. Bronchoalveolar lavage (BAL), blood lymphocytes and bronchial biopsies, analysed both in the epithelium and lamina propria, were stained for T and B lymphocytes, natural killer (NK) cells and different subpopulations of T lymphocytes. In BAL, significantly higher proportions of T lymphocytes (CD3), T lymphocyte activation markers; HLA-DR, CD26+, CD49a+, CD54+ and CD69+, helper T (CD3+4+) and memory helper T lymphocytes (CD4+45RO+29+) and memory T lymphocytes (CD3+45RO+) were found, compared to blood. However, the proportion of IL-2 receptor-positive T lymphocytes (CD25+) was lower in BAL than in blood. A previously described higher ratio of CD3+4+/CD3+8+ in BAL than in blood (3.4 vs 1.7; P = 0.001) was confirmed. In bronchial biopsies, we found significantly higher numbers of CD8+ cell profiles per mm2 in the epithelial compared to the lamina propria compartment. We conclude that healthy never-smoking men have higher levels of activated memory T lymphocytes in BAL than in blood, and that the T-cell subpopulations differ in the epithelial compared to the lamina propria compartment in the bronchial mucosa and these compartments should be analysed separately. It is reasonable to think that there is a gradient from blood to the airway lumen where T cells are recruited from blood to take part in the defense towards damaging agents.

Antigens, CD↗
PubMed1998

Induction of anti-DNA antibodies by immunization with activated lymphocytes and active chromatin.

OBJECTIVE: To investigate the primary autoantigens which contribute to the production of anti-DNA antibodies. These antibodies are serological hallmark and pathogenic factor of systemic lupus erythematosus (SLE). METHODS: Nonautoimmune predisposed BALB/c mice were immunized with concanavalin A (Con A) activated, lipopolysaccharide (LPS) activated and nonactivated syngeneic spleen cells. Nuclei and chromatin from activated/nonactivated lymphocytes were isolated and syngeneic mice were immunized. Sera were taken after the third immunization. IgG anti-dsDNA antibody was determined by ELISA (calf thymus DNA treated with S1 nuclease was used as the coated antigen). The glomerular IgG deposition was observed by immunofluorescence one month after the third immunization. RESULTS: Con A activated T cells and LPS activated B cells induced anti-double stranded (ds) DNA antibody in syngeneic nonautoimmune BALB/c mice and formed the glomerular IgG deposition. Further studies showed that active chromatin isolated from activated lymphocytes induced anti-ds DNA antibody, but not resting chromatin isolated from nonactivated lymphocytes. CONCLUSIONS: Activated lymphocytes and their active chromatin could be the autoimmunogen(s) driving the anti-dsDNA antibodies. The change of chromatin's antigenicity by environmental factors and genetic background may be the common pathway to SLE pathogenesis.

Animals↗
PubMed1988

Regulatory properties of LFA-1 alpha and beta chains in human T-lymphocyte activation.

Lymphocyte function-associated antigen-1 (LFA-1) is a heterodimer composed of an alpha and beta chain that is expressed on the surface of most leukocytes and is an essential molecule for adhesion reactions between cells participating in the immune response. A putative ligand for LFA-1 is the intercellular adhesion molecule ICAM-1 (refs 3-5). Leukocyte adhesion abnormality is found in patients with LFA-1 deficiency. It is not clear whether binding of ligand to the LFA-1 molecule merely spatially orientates cells towards each other or can also induce signals that regulate cell activation and differentiation. We have recently developed a T-cell proliferation assay which uses immobilized anti-CD3 monoclonal antibodies as stimulant and is independent of LFA-1-mediated cellular adhesion. As there is no interference by anti-LFA-1 monoclonal antibodies with the adhesion-dependent activation steps, this T-cell activation system allows us to investigate whether transmembrane signals are induced by binding of ligand to LFA-1 on T cells. Our data indicate that binding of ligand to LFA-1 results in the transduction of regulatory signal across the plasma membrane, rather like other molecules (CD2, CD4, CD8) (refs 8-11) with signal-modifying properties involved in the adhesion of T cells to target/stimulator cells. Indeed, adhesion molecules might generally be important in signal transduction, even in cells not belonging to the immune system.

Antigens, Differentiation, T-Lymphocyte↗
PubMed2002

Method to evaluate the proliferation of activated lymphocytes in a three-dimensional collagen matrix.

It is well known that the enhancement of the cell-matrix interactions represents one of the early steps in the process of lymphocyte activation. However, the information regarding the role of these interactions in the late stages of lymphocyte activation (in particular, the proliferation) is still controversial. This is basically due to the absence of adequate experimental models. In the present work we carried out a step-by-step modification of a well-studied model of mitogen-stimulated lymphocyte activation, adjusting it to the conditions of a three-dimensional collagen matrix (3D-CM). All the changes added to the standard procedure in the process of this modification were rigorously controlled using various experimental models. The final version of the method includes the following steps: (i) 24-h lymphocyte (lymphocyte fraction from mouse spleen) preincubation with mitogens (Con A or LPS) with a subsequent cell wash (parameters being controlled: irreversible lymphocyte activation, independence of the proliferation from cell-cell interactions); (ii) transfer of the activated lymphocytes to (3)H-thymidine containing 3D-CM and incubation for 48 h (controlled parameters: distribution of the radioactive label within the 3D-CM and its biological accessibility to lymphocytes); (iii) degradation of the 3D-CM with bacterial collagenase and cell transfer onto glass fiber filters (controlled parameters: cell viability after cultivation in the 3D-CM and treatment with the collagenase). With this method we found that the proliferation of the Con A- and LPS-stimulated lymphocytes in 3D-CM was dramatically inhibited (by 66.5 +/- 14.9% and by 88.1 +/- 10.2%, respectively). The discovered inhibition of the lymphocyte proliferation was not a consequence of either the ineffectiveness of the mitogens, the disruption of the cell-cell interactions, an insufficient inclusion of the radioactive label into cells, or of a decreased cell viability.

Animals↗
PubMed1994

[Monitoring lymphocyte activity in the peripheral blood of patients after bone marrow transplantation].

BACKGROUND: After bone marrow transplantation serious complications develop which may limit the success of this therapeutic method. One of the early complications is an acute graft versus host reaction. The objective of the investigation was to evaluate the relationship between the number of active lymphocytes in the patient's blood stream after bone marrow transplantation and the development of an acute graft versus host reaction or rejection of the graft, and thus contribute towards prediction or diagnosis of these complications. METHODS AND RESULTS: In 14 patients with acute myeloid leukaemia (3), acute lymphatic leukaemia (1), chronic myeloid leukaemia (6), myelodysplastic syndrome (2) and aplastic anaemia (2) bone marrow was transplanted: the donor was in all instances a HLA identical sibling. However, only 11 patients were evaluated. In the latter changes in the number of circulating active lymphocytes were assessed: their activity was evaluated from nucleolar characteristics expressed by RNA synthesis. Their values at the time of the acute graft versus host reaction (GVHD) varied between 7.4% and 17.3%; at the time when these patients were free from complications they were 2.2%-6.0% (the difference is at the borderline of significance). In 8 patients the rise of active lymphocytes preceded the manifestation of the graft versus host reaction by 3-7 days. At the time of infectious complications after bone marrow transplantation (temperatures of obscure origin, herpetic infections, varicella, adenoviral infections) the number of active lymphocytes did not increase (2.0%-10.0%), as compared with 3.4%-9.5% in the group without complications. CONCLUSIONS: The increased percentage of activated lymphocytes in the peripheral blood stream of patients with an acute graft versus host reaction (GVHD) after bone marrow transplantation results from specific immunological procedures. Their assessment could help with the differential diagnostic difficulties frequently associated with the diagnosis of the acute graft versus host reaction.

Bone Marrow Transplantation↗
PubMed2006

A new extract of the plant Calendula officinalis produces a dual in vitro effect: cytotoxic anti-tumor activity and lymphocyte activation.

BACKGROUND: Phytopharmacological studies of different Calendula extracts have shown anti-inflammatory, anti-viral and anti-genotoxic properties of therapeutic interest. In this study, we evaluated the in vitro cytotoxic anti-tumor and immunomodulatory activities and in vivo anti-tumor effect of Laser Activated Calendula Extract (LACE), a novel extract of the plant Calendula Officinalis (Asteraceae). METHODS: An aqueous extract of Calendula Officinalis was obtained by a novel extraction method in order to measure its anti-tumor and immunomodulatory activities in vitro. Tumor cell lines derived from leukemias, melanomas, fibrosarcomas and cancers of breast, prostate, cervix, lung, pancreas and colorectal were used and tumor cell proliferation in vitro was measured by BrdU incorporation and viable cell count. Effect of LACE on human peripheral blood lymphocyte (PBL) proliferation in vitro was also analyzed. Studies of cell cycle and apoptosis were performed in LACE-treated cells. In vivo anti-tumor activity was evaluated in nude mice bearing subcutaneously human Ando-2 melanoma cells. RESULTS: The LACE extract showed a potent in vitro inhibition of tumor cell proliferation when tested on a wide variety of human and murine tumor cell lines. The inhibition ranged from 70 to 100%. Mechanisms of inhibition were identified as cell cycle arrest in G0/G1 phase and Caspase-3-induced apoptosis. Interestingly, the same extract showed an opposite effect when tested on PBLs and NKL cell line, in which in vitro induction of proliferation and activation of these cells was observed. The intraperitoneal injection or oral administration of LACE extract in nude mice inhibits in vivo tumor growth of Ando-2 melanoma cells and prolongs the survival day of the mice. CONCLUSION: These results indicate that LACE aqueous extract has two complementary activities in vitro with potential anti-tumor therapeutic effect: cytotoxic tumor cell activity and lymphocyte activation. The LACE extract presented in vivo anti-tumoral activity in nude mice against tumor growth of Ando-2 melanoma cells.

Animals↗
PubMed1983

Effects of cyclosporin A on the metabolism of unstimulated and mitogen-activated lymphocytes.

The immunosuppressive drug cyclosporin A (CS-A) reduces the magnitude of T-lymphocyte activation by all mitogenic lectins tested. However, in all cases a proportion of the activation observed is resistant even to very high concentrations of the drug. This proportion depends on the mitogen used, the responses to concanavalin A (Con A) and soybean agglutinin (SBA) being much more strongly inhibited than the responses to phytohaemagglutinin (PHA) or pokeweed mitogen (PWM). The differential effects of CS-A on lymphocyte activation by these mitogens could not be accounted for by the magnitude of the mitogenic response, the mitogen concentration used or the dependence of the responses on the presence of accessory cells, and they were maintained when several different procedures were used to assess the degree of activation. CS-A effectively inhibited inhibited lymphocyte activation. CS-A effectively inhibited lymphocyte activation only when added prior to, or very shortly after, the mitogen. Its ability to inhibit the response to PHA was lost more rapidly than that of Con A. The rate of protein synthesis by unstimulated lymphocytes was also affected by CS-A over the concentration range required to inhibit activation by mitogens. Although this effect was smaller than the inhibition of mitogen activation, it was highly significant and reproducible, and could not be accounted for by inhibition of spontaneous activation occurring in the unstimulated cultures.

Animals↗