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Correction of antigen-specific T cell defects in aged murine gut-associated lymphoid tissues an immune intervention by combined adoptive transfer of an antigen-specific immunoregulatory CD4 T cell subset and interleukin 2 administration.

Gut-associated lymphoid tissues (GALT) from aged mice enterically immunized with Mycobacterium paratuberculosis protoplasmic antigen show hyperreactive humoral immune responses; this hyperresponsiveness can be corrected to a considerable extent, but not entirely, by systemic administration of interleukin 2 (IL 2) alone. The aim of the present study was to determine further whether the hyperreactivity in the antigen-specific humoral immune responses in aged GALT could be fully restored by adoptive transfer of in vitro expanded antigen-specific IL 2-dependent helper (CD4+VV-) T cells from GALT in conjunction with recombinant IL 2 administration. The results show that the age-associated hyperresponsiveness in gut mucosal antigen-specific humoral immune responses can be entirely corrected by adoptive transfer with the antigen-specific GALT T helper cells together with in vivo IL 2 administration. The mechanism of this restoration involves reversal of the decline in antigen-specific CD8+ suppressor T cell functions in aged GALT.

Aging↗

Adoptive transfer of immature dendritic cells with autologous or allogeneic tumor cells generates systemic antitumor immunity.

Dendritic cells (DCs) are potent antigen-presenting cells that are capable of priming systemic antitumor immune responses in animal tumor models. However, many of the model tumor systems tested need definition of the specific tumor antigens involved. To use DCs in situations that are more relevant to the majority of human cancers, where the antigens are unknown, we have tested the adoptive transfer of immature DCs in mouse colorectal and melanoma models of varying immunogenicity but with undefined antigens. When DCs admixed with a syngeneic primary tumor inoculum were seeded s.c., the growth of the primary tumor was unchanged; however, if the primary tumor was then surgically excised and the animal was rechallenged with the same tumor, significant protection (75%) was generated when DCs were present in the original primary inoculum of a moderately immunogenic colorectal model (CMT93tk). This effect was not observed when a nonimmunogenic melanoma (B16) was tested in an identical protocol. Next, DCs were injected directly into 6-9-mm established tumors; again, protection (55%) was achieved against a secondary tumor challenge following excision of the primary, but only in the CMT93tk model of moderate immunogenicity. To increase the clinical relevance of this approach still further, we tested irradiated allogeneic K1735 melanoma cells mixed with syngeneic DCs as a vaccine against subsequent challenge with the poorly immunogenic syngeneic melanoma B16. The allogeneic vaccine alone was ineffective, but when admixed with DCs, a significant number of animals rejected a subsequent B16 challenge, suggesting that DCs are able to prime an immune response against melanoma antigens shared between K1735 and B16. The generation of systemic antitumor immunity by adoptive transfer of DCs has significant clinical potential because it is technically straightforward and does not require the definition of specific tumor antigens.

Animals↗

CD8+ T-cells are required for adoptive transfer of the BB rat diabetic syndrome.

LGLs with NK activity account for the majority of BB rat PBLs expressing CD8, and it has been suggested that these LGL/NK cells are involved in the pathogenesis of the BB rat diabetic syndrome. By using a recently developed mouse MoAb, 3.2.3, specific for rat LGL, we demonstrate that BB and WF rat LGLs are phenotypically and functionally similar. To directly assess the role of LGLs in the development of diabetes in vivo, an adoptive transfer of T-cells to young LGL/NK cell-depleted diabetes-prone BB rats was performed. CD4+8- and CD4-8+ T-cells (> 98.5% pure), isolated from diabetic BB rats, were activated in vitro and injected into 30-day-old diabetes-prone BB rats. Recipients were either chronically injected with 3.2.3 (n = 15) or received an isotype-matched irrelevant MoAB (n = 14). Secondary lymphoid organs of 3.2.3-treated recipients contained < 0.1% 3.2.3+ lymphocytes, and this depletion was associated with a major decrease in the NK activity of their splenocytes. Despite this, the incidence of diabetes in 3.2.3-treated animals (40%) was not significantly different from that observed in control recipients (57%). Thus, the BB rat diabetic syndrome can be adoptively transferred in the absence of LGL/NK cells, suggesting that BB rat CD8+ T-cells are involved in the diabetogenic process. To assess the pathogenic role of CD8+ T-cells, we compared the incidence of diabetes in three groups of diabetes-prone BB recipients after injection of T-cells isolated from diabetic donors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Adoptive transfer of minor histocompatibility antigen-specific T lymphocytes eradicates leukemia cells without causing graft-versus-host disease.

Adoptive transfer of T cells reactive to minor histocompatibility antigens has the unmatched ability to eradicate malignant hematopoietic cells. Unfortunately, its use is hampered by the associated graft-versus-host disease. The critical issue of a possible dissociation of the antileukemic effect and graft-versus-host disease by targeting specific minor histocompatibility antigens remains unresolved because of the unknown nature and number of minor histocompatibility antigens necessary or sufficient to elicit anti-leukemic activity and graft-versus-host disease. We found that injection of T lymphocytes primed against a single major histocompatibility complex class I-restricted immunodominant minor histocompatibility antigen (B6dom1) caused no graft-versus-host disease but produced a curative anti-leukemic response. Avoidance of graft-versus-host disease required that no other host-reactive T cells be co-injected with T cells primed with B6dom1. Here we show that effective and non-toxic immunotherapy of hematologic malignancies can be achieved by targeting a single immunodominant minor histocompatibility antigen.

Adoptive Transfer↗

Adoptive transfer of experimental allergic encephalomyelitis with lectin-activated spleen cells.

Adoptive transfer of experimental allergic encephalomyelitis (EAE) was achieved in Lewis rats using spleen cells incubated in vitro with various lectins. When stimulated with concanavalin A (Con A), its derivative succinyl-Con A, Lens culinaris or Pisum sativum agglutinin, spleen cells obtained from rats immunized with encephalitogenic emulsion could transfer EAE to normal syngeneic recipients. In contrast, spleen cells stimulated with Phaseolus vulgaris, Robinia pseudoacacia or Wisteria floribunda agglutinin did not transfer EAE. Transfer of EAE with Con A-activated spleen cells was abolished by the specific hapten inhibitor, alpha-methyl-D-mannoside, but not by D-glucose. Our data indicate that the in vitro responses to lectins may differ among T cell subpopulations. Lectins may prove useful for investigating the nature of EAE-effector cells and the mechanisms of immune regulation in this autoimmune central nervous system disease.

Animals↗

Characteristics of lymphoid cells that adoptively transfer immunity to Rickettsia mooseri infection in mice.

The capacity of adoptively transferred immune lymphoid cells or passively transferred immune serum to alter the course of an established Rickettsia mooseri (R. typhi) infection in the spleen was evaluated in BALB/c mice. Immune cells, but not immune serum, controlled the established infection. An effective lymphocyte was a T-cell which had to possess a capacity to divide.

Animals↗

Host CD4+ T lymphocytes are required for the synergistic action of interferon-alpha/beta and adoptively transferred immune cells in the inhibition of visceral ESb metastases.

Effective adoptive immunotherapy of immunocompetent DBA/2 mice challenged i.v. with the highly metastatic ESb T-cell lymphoma required the combined treatment of recipient mice with tumor-sensitized spleen cells and IFN-alpha/beta. In contrast, immune spleen cells and IFN-alpha/beta treatment did not increase the survival time of ESb-injected DBA/2-nu/nu mice, DBA/2-bg/bg mice, or normal DBA/2 mice injected with antibody to CD4. Treatment of immunocompetent DBA/2 mice with antibody to asialo-GM1, silica, dichloromethylene diphosphonate-containing liposomes, or 500 rads whole-body gamma-irradiation did not diminish the antimetastatic action of ESb-immune cells and IFN-alpha/beta. These results indicate that adoptively transferred immune T lymphocytes and IFN-alpha/beta act together with host CD4+ T lymphocytes/factors to inhibit ESb visceral metastases. Combined treatment with ESb-immune cells together with interleukin-1 beta (IL-1 beta), IL-2, tumor necrosis factor-alpha, or granulocyte-macrophage colony-stimulating factor did not increase the survival time of normal DBA/2 mice challenged with ESb cells. In contrast, IL-12, which had only a slight antimetastatic effect when administered alone, did synergize with ESb-immune spleen cells and increased the survival time of ESb-challenged mice to a similar extent as did IFN-alpha/beta and immune spleen cells. Treatment of DBA/2 mice with potent antibody to IFN-alpha/beta did not abrogate the capacity of IL-12 and ESb-immune spleen cells to inhibit ESb metastases. Unlike immunotherapy with ESb-immune cells and IFN-alpha/beta, ESb-immune cells together with IL-12 inhibited ESb metastases in immunodeficient DBA/2-bg/bg mice.

Animals↗

Adoptive transfer of cytotoxic T lymphocytes induced by CD86-transfected tumor cells suppresses multi-organ metastases of C1300 neuroblastoma in mice.

In this study, we examined the therapeutic antitumor effect of cytotoxic T lymphocytes (CTL) generated against CD86-transfected mouse neuroblastoma C1300. We first generated the transfectant, CD86 + C1300, expressing a high level of mouse CD86 on the cell surface. While CD86 + C1300 cells were rejected in syngeneic A/J mice when inoculated subcutaneously, neither vaccination nor any therapeutic antitumor effect was obtained, implying that C1300 may be a poorly immunogenic tumor. However, in vitro stimulation of splenocytes from either C1300-bearing or CD86 + C1300-rejecting mice with CD86 + C1300 cells resulted in remarkable CTL activity against C1300 cells. The CTL activity induced by CD86 + C1300 was mediated by T cell receptor/CD3 and CD8 and was further enhanced by the addition of interleukin-2. Intravenous inoculation of C1300 cells led to multiple organ metastases including the liver, lung, kidney, ovary, lymph node and bone marrow. To examine the therapeutic effect of CTL in this metastasis model, CTL induced by parental or CD86 + C1300 cells were administrated into C1300-bearing mice. Adoptive transfer of CD86 + C1300-induced CTL resulted in marked elimination of multi-organ metastases and prolonged survival in almost all mice, 70% of which survived indefinitely. These results indicate that adoptive transfer of CTL induced by CD86-transfected tumor cells in vitro would be effective and useful for tumor immunotherapy against poorly immunogenic tumors.

Animals↗

Use of adoptive transfer of T-cell-antigen-receptor-transgenic T cell for the study of T-cell activation in vivo.

Adoptive transfer of TCR-transgenic T cells uniformly expressing an identifiable TCR of known peptide/MHC specificity can be used to monitor the in vivo behavior of antigen-specific T cells. We have used this system to show that naive T cells are initially activated within the T-cell zones of secondary lymphoid tissue to proliferate in a B7-dependent manner. If adjuvants or inflammatory cytokines are present during this period, enhanced numbers of T cells accumulate, migrate into B-cell-rich follicles, and acquire the capacity to produce IFN-gamma and help B cells produce IgG2a. If inflammation is absent, most of the initially activated antigen-specific T cells disappear without entering the follicles, and the survivors are poor producers of IL-2 and IFN-gamma. Our results indicate that inflammatory mediators play a key role in regulating the anatomic location, clonal expansion, survival and lymphokine production potential of antigen-stimulated T cells in vivo.

Adjuvants, Immunologic↗

Increased severity of Candida vaginitis in BALB/c nu/nu mice versus the parent strain is not abrogated by adoptive transfer of T cell enriched lymphocytes.

The role of the host immune system in combating candidal infections in the vagina is poorly understood. A murine model of Candida vaginitis was used to elucidate the role of T cells in a candidal infection. Athymic BALB/c nu/nu mice or normal BALB/c mice were induced into estrus and then infected with 1 x 10(6) Candida albicans intravaginally. The infection was monitored over 1 week. Samples from blood, small intestine, tongue, kidney, spleen, liver, uterus and vagina were tested for recoverable C. albicans. Histology of the vagina was assessed for both inflammation and extent of infection. Results indicated that the BALB/c nu/nu mice had similar levels of vaginal yeast load to the normal BALB/c mice. In 25-30% of nude mice Candida was also recovered from extra vaginal sites (kidney, liver, small intestine), however, extra vaginal dissemination was not observed in any normal BALB/c animals. Histologically, both the nu/nu and control BALB/c had similar levels of vaginal inflammation; however, the nu/nu mice had more florid fungal growth in the vaginal epithelium. Adoptive transfer of either immune or non-immune BALB/c T cells into nude mice had no affect on either infection or vaginal inflammation. Immunohistochemical staining of vaginal tissues from normal BALB/c mice or nude mice adoptively transferred with either immune or non-immune T cells with anti-CD3 monoclonal antibody revealed no significant difference between groups in the numbers of CD3+ vaginal T cells. However, in mice receiving either immune or non-immune T cells no yeast was recovered from any tissues except the vagina. These data show that T cells have a limited role in protecting the vagina from C. albicans infection.

Animals↗

Primed lymphocytes are boosted by type II collagen of their hosts after adoptive transfer.

A central question in understanding autoimmunity is whether an endogenous self-antigen can drive an immune response initially triggered by a foreign one. This possibility is here tested by adoptive transfer, in which T and B cells from mice primed with foreign type II collagen were transferred into irradiated syngeneic hosts. Previous work with other protein antigens has established that primed cells normally respond only if boosted after transfer with antigen. In the present case, and in respect only to that portion of the antibody response able to bind to endogenous type II collagen, that requirement did not hold. This indicates that the anti-self component is indeed driven by endogenous antigen, which the transferred lymphocytes presumably obtain from their adoptive hosts. The transfers were carried out in C57BL10.A x DBA/1 mice using donors primed with either chick or bovine collagen, and the non-boosted responses, presumably driven by endogenous antigen, could be followed in a proportion of the recipients for as long as 45 days.

Animals↗

Characterization of variant and parental-cross-protective immunity to immunogenic variants of a murine fibrosarcoma using the local adoptive transfer assay.

The purpose of this study was to characterize the lymphocyte populations responsible for rejection of immunogenic (Imm+) tumor variants, and the cross-protective immunity engendered by Imm+ variants against the weakly immunogenic parental tumor. Immunogenic clones of the weakly immunogenic methylcholanthrene-induced fibrosarcoma MCA-F have been generated using 1-methyl-3-nitro-1-nitrosoguanidine, 5-aza-2'-deoxycytidine, or ultraviolet radiation (UV-B; 280-320 nm). These clones grow progressively in immunosuppressed adult-thymectomized irradiated mice, but are rejected by immunocompetent syngeneic hosts. The parental MCA-F tumor grows progressively in both groups. Mice that have rejected a challenge of 1 x 10(5) Imm+ cells show an anamnestic immune response against both the Imm+ clone and the parental MCA-F tumor. Using the local adoptive transfer assay and depletion of T-cell subsets with antibody plus complement, we show that immunity induced by the Imm+ variants against the parent MCA-F was mediated by the Thy1.2+, L3T4a+ population without an apparent contribution by Lyt2.1+ cells. Although antivariant immunity was also dependent upon Thy1.2+ cells, depletion of either the L3T4a+ or the Lyt2.1+ cells failed to abolish immunity against the variant. A role for Lyt2.1+ T lymphocytes in antivariant immunity, but not antiparent immunity, was supported by the results of cytotoxic T lymphocyte (CTL) assays. Following immunization with high numbers (1 x 10(5) to 5 x 10(5) of viable Imm+ cells, antivariant, but not antiparent CTL activity was detected in mixed lymphocyte tumor cell cultures. Immunization with lower numbers (3 x 10(4] of viable Imm+ or with high numbers of mitomycin-C-treated Imm+ engenders only antivariant immunity without parental cross-protection. Under these conditions lymphocytes mediating immunity against the variant in the local adoptive transfer assay were exclusively of the Thy1.2+, L3T4a+ phenotype, with no contribution from the Lyt2.1+ cells. Identical results were obtained for Imm+ clones of MCA-F induced by methylnitronitrosoguanidine, 5-azadeoxycytidine, and UV-B, suggesting that the nature of the antitumor immunity engendered by Imm+ is not significantly affected by the agent used. Furthermore, these results demonstrate that the cross-reactivity and cellular effectors of antitumor immunity in this system are influenced by the immunizing dose of Imm+ cells: the predominant effectors of both antivariant and parental-cross-reactive immunity were of the CD4+ T cell subclass, with a CD8+ cytotoxic population contributing to antivariant immunity only after high-dose immunization.

Animals↗

Adoptive transfer of low numbers of CD4+ T cells into SCID mice chronically treated with soluble IL-4 receptor does not prevent engraftment of IL-4-producing T cells.

After intravenous injection of 10(5) purified, lymph node (LN)-derived dm2 (H-2d/Ld-) CD4+ T cells into young C.B-17 scid/scid (severe combined immunodeficiency, SCID) mice (H-2d/Ld+), the transplanted Ld-T cells show a selective pattern of engraftment: they repopulate the spleen, the lamina propria of the small intestine and the mesenteric LN (but not other peripheral LN) of the immunodeficient host. CD4+ cells repopulating different lymphoid organs of the SCID recipient mice produce interleukin-2 (IL-2) and interleukin-4 (IL-4) in response to polyclonal stimulation in vitro. Some evidence has recently been provided that cytokines (e.g. IL-4) present at the site of antigen stimulation in vivo decisively influence the pattern of cytokines expressed by T cells activated at these sites. We therefore asked if neutralization of IL-4 by chronic treatment of SCID mice with high doses of recombinant soluble IL-4 receptor (sIL-4R) changes the IL-4 or IL-2 expression pattern of CD4+ T cells adoptively transferred into young SCID recipients. Transplanted SCID mice were chronically treated with two different, recombinant murine sIL-4R proteins. The experimental series further included groups of transplanted SCID mice treated with a recombinant human sIL-4R protein (which does not bind murine IL-4), treated with the anti-murine IL-4 monoclonal antibody (MoAb) 11B11, or non-treated. Transplanted SCID mice treated with the recombinant murine sIL-4R protein preparations displayed detectable sIL-4R serum levels, which demonstrates that the substitution therapy could maintain neutralizing serum levels of anti-IL-4 activity in SCID mice. By contrast, no serum sIL-4R levels were detectable in the sensitive ELISA readout in transplanted SCID mice which were non-treated, treated with the MoAb 11B11, or treated with the recombinant humans sIL-4R protein. The efficiency and the pattern of CD4+ T-cell engraftment, and the lymphokine-producing phenotype of the engrafted dm2 CD4+ cells, was not affected by the continuous IL-4-neutralizing treatment of mice with either the MoAb 11B11 or the soluble IL-4R preparations. Hence, in contrast to the published evidence of the dramatic effect of IL-4 on the lymphokine-producing phenotype of CD4+ T cells stimulated in vitro or in vivo, the chronic suppression in vivo of IL-4 activity (by either different sIL4-R protein constructs, or by the anti-IL-4 MoAb 11B11) did not lead to preferential engraftment of Th1-type CD4+ T cells after adoptive transfer of CD4+ T-cell populations into an immunodeficient recipient.

Animals↗

Recombinant interleukin 2 stimulates in vivo proliferation of adoptively transferred lymphokine-activated killer (LAK) cells.

We previously reported that the adoptive transfer of lymphokine-activated killer (LAK) cells plus repetitive injections of recombinant interleukin 2 (IL 2) produced a marked reduction in established pulmonary metastases from a variety of murine sarcomas. The requirement for the exogenous administration of IL 2 prompted a subsequent examination of the role of IL 2 in the in vivo function of transferred LAK cells. The in vivo proliferation and migration patterns of lymphoid cells in C57BL/6 mice were examined after i.v. transfer of LAK cells alone, i.p. injection of IL 2 alone, or the combination of LAK cells and IL 2. A model for in vivo labeling of the DNA of dividing cells was used in which mice were injected with 5-[125I]-iodo-2'-deoxyuridine (125IUdR) and, 20 hr later, their tissues were removed and were counted in a gamma analyzer. A proliferation index (PI) was calculated by dividing the mean cpm of organs of experimentally treated mice by the mean cpm of organs of control mice. In animals given LAK cells alone, the lungs and liver demonstrated little if any uptake of 125IUdR above saline-treated controls (PI = 2.5 and 0.8, respectively, on day 5), whereas the same organs of mice receiving 6000 U of IL 2 alone displayed higher radiolabel incorporation (PI = 7.1 and 5.9, respectively). When mice were given LAK cells plus 6000 U of IL 2, their tissues showed an additional increase in 125IUdR uptake. In the spleen, kidneys, and mesenteric lymph nodes, IL 2 treatment alone (6000 U) produced elevated PI values that were not, however, additionally increased if LAK cells were also administered. To separate the stimulatory effects of IL 2 on host lymphocyte proliferation from similar IL 2 effects on injected LAK cells, these studies were repeated in mice immunosuppressed by 500 rad total body irradiation. Pre-irradiation of the host sufficiently reduced endogenous lymphoid expansion stimulated by IL 2 so as to allow the demonstration that IL 2 also induced the proliferation of the transferred LAK cells. A variety of studies confirmed that the injected LAK cells were actively proliferating in tissues in vivo under the influence of IL 2. Substitution of "normal" LAK cells with fresh and cultured (without IL 2) splenocytes, or irradiated LAK cells did not result in increased 125IUdR uptake in tissues. Histologic studies corroborated the findings of the 125IUdR incorporation assays and revealed extensive lymphoid proliferation in irradiated mice receiving LAK cells plus IL 2.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Adoptive transfer of vaccine-induced peripheral blood mononuclear cells to patients with metastatic melanoma following lymphodepletion.

Cancer vaccines can induce the in vivo generation of tumor Ag-specific T cells in patients with metastatic melanoma yet seldom elicit objective clinical responses. Alternatively, adoptive transfer of autologous tumor-infiltrating lymphocytes (TIL) can mediate tumor regression in 50% of lymphodepleted patients, but are logistically and technically difficult to generate. In this study, we evaluated the capability of vaccine-induced PBMC to mediate tumor regression after transfer to patients receiving the same chemotherapy-induced lymphodepletion used for TIL transfer therapy. Autologous PBMC from nine gp100-vaccinated patients with metastatic melanoma were stimulated ex vivo with the gp100:209-217(210M) peptide and transferred in combination with high-dose IL-2 and cancer vaccine. Transferred PBMC contained highly avid, gp100:209-217 peptide-reactive CD8(+) T cells. One week after transfer, lymphocyte counts peaked (median of 14.3 x 10(3) cells//microl; range of 0.9-59.7 x 10(3) cells/microl), with 56% of patients experiencing a lymphocytosis. gp100:209-217 peptide-specific CD8(+) T cells persisted at high levels in the blood of all patients and demonstrated significant tumor-specific IFN-gamma secretion in vitro. Melanocyte-directed autoimmunity was noted in two patients; however, no patient experienced an objective clinical response. These studies demonstrate the feasibility and safety of using vaccine-induced PBMC for cell transfer, but suggests that they are not as effective as TIL in adoptive immunotherapy even when transferred into lymphodepleted hosts.

Adoptive Transfer↗

Adoptive transfer of experimental autoimmune dacryoadenitis in susceptible and resistant mice.

Strains of mice with diverse genetic backgrounds were compared for their ability to develop experimental autoimmune dacryoadenitis (EAD) after immunization with a purified lacrimal gland antigen (LG-Ag) in complete Freund's adjuvant. Susceptibility to the induction of EAD was linked to the murine H-2 histocompatibility background. SJL/J mice with the H-2s haplotype were the most susceptible to EAD, developing extensive cellular infiltration of the lacrimal gland, but those with the H-2d haplotype (BALB/c mice) or H-2q haplotype (DBA/J mice) were resistant to EAD, having little or no infiltration of the lacrimal gland. There was no correlation between the development of EAD and either the antibody response or the in vitro lymphocyte proliferative response to LG-Ag. The differences in the induction of EAD observed between susceptible and resistant strains resided in the different capacity of their lymphocytes to transfer disease. Splenocytes from susceptible SJL/J mice sensitized with LG-Ag in CFA could be activated in vitro with LG-Ag to transfer disease to normal syngeneic recipients. The capacity for adoptive transfer was abrogated by treatment with anti-Thy 1.2 antibody plus complement, an indication that T cells are responsible for the transfer of EAD. However, EAD cannot be transferred with the donor cells from resistant mice even after they have been cultured in vitro with LG-Ag. These results suggest that T cells play a major role in the induction of EAD and that variations in susceptibility are under the control of distinct genetically inherited mechanisms that may include active suppression.

Animals↗

Identification and characterization of B cell precursors in rat lymphoid tissues. I. Adoptive transfer assays for precursors of TI-1, TI-2, and TD antigen-reactive B cells.

Quantitative adoptive transfer assays were developed to detect the precursors of TI-1, TI-2, and TD antigen-reactive B cells in rat lymphoid tissues. Studies on the immune responses in normal and athymic nude rats validate the use of TNP-lipopolysaccharide as a TI-1 antigen, TNP-Ficoll as a TI-2 antigen, and SRBC as a TD antigen in rats. The precursors to these immunologically competent B cells are detected, following transfer into irradiated histocompatible recipients, by their ability to generate expanded populations of antigen-reactive B cells capable of mounting antibody responses (splenic IgM plaque-forming cells) to these antigens. Maximal numbers of antigen-reactive B cells emerge in antigenically naive rats after an interval of 7-12 days following transfer of donor lymphoid cells and decline rapidly thereafter. The delayed responses in adoptive recipients reconstituted with spleen cells are proportional to the numbers of spleen cells transferred and are shown to be primarily donor derived using histocompatible Ig kappa chain alloantigen disparate rat strain combinations. The precursors of TI-1, TI-2, and TD antigen-reactive B cells are present in both donor spleen and bone marrow. However, precursor cells to TI-1 and TD antigens are largely absent from donor lymph node cells, whereas precursors to the TI-2 antigen are as prevalent in donor lymph node as in donor spleen. These results support the hypothesis that newly formed virginal B cells represent transient populations of precursor cells that undergo further proliferation and differentiation in the spleen before acquiring immunological competence. The results also suggest that the precursors of TI-2 antigen-reactive B cells differ developmentally from those of TI-1 and TD antigen-reactive B cells, and that the antigen-reactive progeny of these precursors require additional stimulation in order to join the pool of long-lived peripheral B cells.

Animals↗

Babesia microti in mice. Adoptive transfer of immunity with serum and cells.

Protection against infection with Babesia microti in mice was passively transferred with either serum or cells. Immune spleen cells were more effective than were immune mesenteric lymph node (MLN) cells in reducing parasitaemias in recipient mice, and the level of protection correlated with the donor to recipient ratio rather than with the number of cells transferred. Protection against primary infection in recipient mice was adoptively transferred by nylon wool adherent, B cell enriched subpopulations of spleen cells. In contrast, higher peak parasitaemias were apparent in mice which received nylon wool non-adherent, T enriched spleen cells in comparison with the control mice. However, if the recipient mice were reinfected, control of this second infection was greatest in the recipients of the T enriched cell subpopulation. Treatment of the protective nylon wool adherent, B cell subpopulation with anti-theta serum and complement abolished both the protective effect and the anamnestic antibody response in the recipient mice. This suggested that primed T cells controlled the expression of the protective antibody response by primed B cells.

Animals↗