Opposite effects of total lymphoid irradiation on T cell-dependent and T cell-independent antibody responses

The effect of total lymphoid irradiation (TLI) on the primary antibody response to the dinitrophenylated heterologous protein, keyhole limpet hemocyanin (DNP-KLH), in complete Freund's adjuvant (CFA), and to the trinitrophenylated polysaccharide antigen, Brucella abortus (TNP-BA), was studied in BALB/c mice. The antibody response to both antigens was diminished in comparison with nonirradiated mice when antigens were injected within 3 days after TLI. When the mice were immunized 30 days after completion of TLI the antibody response to DNP-KLH in CFA was still diminished, but the antibody response to TNP-BA was enhanced 5- to 10-fold as compared with that of control animals. The opposite effect of TLI on the two antibody responses was also observed in a syngeneic primary adoptive transfer system.     

Total lymphoid irradiation reduces IgG autoantibody production and enhances specific antibody responses in NZB/NZW F1 mice

Thymus-independent primary antibody responses were studied in young and old (9 months) untreated and TLI-treated NZB/NZW and BALB/c mice. Untreated old NZB/NZW mice had a low primary response to Brucella abortus (BA) as compared to that of young NZB/NZW and BALB/c mice. However, TLI treatment resulted in a 130-fold increase in the IgG anti-BA primary antibody response at day 21 postimmunization, achieving similar levels to those of young NZB/NZW or nonautoimmune BALB/c mice. Anti-TNP responses to trinitrophenylated BA or Ficoll were masked by high background levels of anti-TNP antibodies. Despite the increase in the anti-BA response, spontaneous immunoglobulin secretion and autoantibody levels were markedly decreased after TLI in old NZB/NZW mice.     

Polyclonal activation of the murine immune system by an antibody to IgD. X. Evidence that the precursors of IgG1-secreting cells are newly generated membrane IgD+B cells rather than the B cells that are initially activated by anti-IgD antibody

Injection of BALB/c mice with an affinity-purified goat antibody to mouse IgD (GaM delta) stimulates T cell-independent B cell activation as well as later T cell activation. Activated T cells then induce polyclonal differentiation of B cells into IgG1-secreting cells, which results in an approximately 100-fold increase in serum IgG1 level. It is not known whether the same B cells that are initially activated by GaM delta are the progenitors of the IgG1-secreting cells. To investigate this issue a system was developed in which CB20 mice, which are congenic to BALB/c mice but express Ig of the beta allotype rather than the BALB/c alpha allotype, were injected with GaM delta and simultaneously or subsequently also received BALB/c B cells. The IgG1 response generated by the donor BALB/c B cells was quantitated by an assay specific for IgG1 of the alpha allotype. Our experiments with this system indicate that: 1) BALB/c B cells transferred 2 days after CB20 mice were injected with GaM delta generate a much larger IgG1 response than do BALB/c B cells transferred simultaneously with GaM delta antibody; 2) B cells that express membrane IgD generate the great majority of this response; 3) differences in the magnitudes of the responses of BALB/c B cells transferred at different times after CB20 mice were injected with GaM delta antibody cannot be explained by differences in homing of the donor B cells to the host spleen or by short survival of donor BALB/c B cells after their transfer; and 4) the response made by donor BALB/c B cells transferred 2 days after CB20 mice were injected with GaM delta is proportionate to donor cell representation in the host spleen 1 day after their transfer, whereas the response made by donor cells transferred simultaneously with GaM delta is disproportionately small. These observations suggest that most of the IgG1 antibody made by GaM delta-injected mice is generated by newly produced, mIgD+ B cells that appear approximately 2 days after GaM delta injection, rather than by those B cells that are present in the spleen at the time of GaM delta injection, and support the view that signals that induce B cell secretion of Ig require an interaction with at least partially activated Th cells.     

Treatment of NZB/NZW mice with total lymphoid irradiation: long-lasting suppression of disease without generalized immune suppression

We used total lymphoid irradiation (TLI; total dose = 3400 rad) to treat the lupus-like renal disease of 6-mo-old female NZB/NZW mice. Similar to our past studies, this treatment resulted in a marked prolongation of survival, decrease in proteinuria, and decrease in serum anti-DNA antibodies compared with untreated littermate controls. Although there was no evidence of disease recurrence in TLI-treated mice until after 12 mo of age, the in vitro proliferative response to phytohemagglutinin by NZB/NZW spleen cells recovered within 6 wk such that responses were greater than control NZB/NZW animals. A similar recovery and overshoot after TLI were evident in the primary antibody response to the T cell-dependent antigen sheep red blood cells (SRBC). Both the total and IgG anti-SRBC antibody responses after TLI were greater than those of untreated NZB/NZW controls, and were comparable with those of untreated non-autoimmune mice. Despite this increased response to mitogens and antigens after TLI, we noted a decrease in spontaneous splenic IgG-secreting cells and a decrease in IgG but not IgM antinuclear antibody production. Nonspecific suppressor cells of the mixed leukocyte response were detectable in the spleens of NZB/NZW mice early after TLI. However, the disappearance of suppressor cells was not associated with recrudescence of disease activity. Furthermore, transfer of large numbers of spleen cells from TLI-treated NZB/NZW mice did not result in disease suppression in untreated age-matched recipients. In summary, treatment of NZB/NZW mice with TLI results in a prolonged remission in autoimmune disease, which is achieved in the absence of generalized immunosuppression.     

Spleen cells from adult mice given total lymphoid irradiation (TLI) or from newborn mice have similar regulatory effects in the mixed leukocyte reaction (MLR). II. Generation of antigen-specific suppressor cells in the MLR after the addition of spleen cells from newborn mice

Spleen cells from newborn BALB/c mice were added to the mixed leukocyte reaction (MLR) between a variety of responder and stimulator cells. The newborn cells nonspecifically suppressed the uptake of (3H)-thymidine and the generation of cytolytic cells regardless of the responder-stimulator combination used. Suppressor cell activity fell rapidly during the first 4 days after birth, and could not be detected by day 20. Newborn spleen cells inhibited the generation of nonspecific suppressor cells during the MLR but did not inhibit the generation of antigen-specific suppressor cells. Thus, newborn spleen cells exhibit a pattern of regulation of the MLR similar to that reported previously for spleen cells from adult mice given total lymphoid irradiation (TLI). These regulatory interactions provide a model that explains the ease of induction of transplantation tolerance in vivo in newborn mice and in TLI-treated adult mice.     

Deficits in T helper cells after total lymphoid irradiation (TLI): reduced IL-2 secretion and normal IL-2 receptor expression in the mixed leukocyte reaction (MLR)

Spleen cells from BALB/c mice treated with total lymphoid irradiation (TLI) and from normal, unirradiated mice were compared in the mixed leukocyte reaction (MLR). Although the percentage of CD4+ cells in the spleen was close to normal, 4 to 6 weeks after TLI, the MLR of unfractionated spleen cells from irradiated mice was more than 10-fold lower than controls. A similar reduction was observed when purified CD4+ cells were used as responders in the MLR. Secretion of IL-2 by cells from irradiated mice was also about 10-fold lower than controls. However, the percentage of CD4+ and CD8+ cells which expressed IL-2 surface receptors during the MLR was similar using spleen cells from irradiated and control mice. Addition of an exogenous source of IL-2 restored the proliferative capacity of the irradiated cells and suggests that the lack of IL-2 secretion is the likely explanation of the marked deficit in the MLR of CD4+ spleen cells after TLI.     

Production of BSF-1 during an in vivo, T-dependent immune response

BSF-1, a cytokine produced by some T lymphocyte tumors, has been shown to act with anti-Ig antibodies to stimulate B lymphocyte proliferation, to independently induce resting B lymphocytes to increase their expression of surface Ia antigen, and to induce some activated B lymphocytes to differentiate into IgG1- or IgE-secreting cells. To determine whether BSF-1 might be secreted by normal lymphoid cells in the course of a physiologic immune response, BALB/c mice were injected with an affinity-purified goat antibody to mouse IgD (GaM delta), which induces the generation of a large, polyclonal T-dependent IgG1 response; 4-hr culture supernatants of spleen cells from these mice were prepared, and these supernatants were assayed for BSF-1 activity by analyzing their ability to induce BALB/c nu/nu spleen cells to increase their expression of cell surface Ia in vitro. Culture supernatants of unfractionated spleen cells removed from mice 4 to 8 days after GaM delta antibody injection induced substantial increases in B lymphocyte surface Ia expression; these increases were blocked by a monoclonal anti-BSF-1 antibody. Culture supernatants of spleen cells from untreated BALB/c mice or from untreated or GaM delta antibody-treated BALB/c nu/nu mice induced small to moderate increases in B cell surface Ia expression, and GaM delta antibody itself induced large increases in B cell surface Ia expression; however, these increases were not significantly blocked by a monoclonal anti-BSF-1 antibody. A culture supernatant of T cell-enriched spleen cells from untreated mice induced small increases in B cell surface Ia expression that were inhibited by anti-BSF-1 antibody, as was the larger increase in B cell Ia expression induced by a culture supernatant of T cell-enriched spleen cells from mice sacrificed 3 days after GaM delta injection. On the other hand, T cell-depleted spleen cells from BALB/c mice injected with GaM delta antibody 7 days before sacrifice failed to generate culture supernatants with BSF-1 activity. Supernatants prepared from spleen cells taken from untreated mice or mice treated with GaM delta antibody 1 to 3 days before sacrifice did not block the ability of purified BSF-1 to induce an increase in B cell surface Ia expression, and thus did not contain inhibitors of BSF-1 activity.(ABSTRACT TRUNCATED AT 400 WORDS)     

Anti-tumor effects of allogeneic bone marrow transplantation in (NZB X NZW)F1 hybrids with spontaneous lymphosarcoma

Untreated female (NZB X NZW)F1 hybrid mice (B/W F1) were found to develop lymphosarcoma spontaneously as they aged. Tumor incidence was evaluated in B/W F1 mice immunosuppressed with total lymphoid irradiation (TLI) and in TLI-conditioned B/W F1 mice reconstituted with 3 X 10(7) BALB/c bone marrow (BM) cells. BALB/C leads to B/W F1 chimerism (79 to 89% BALB/c-type cells) was confirmed by typing peripheral blood lymphocytes with specific alloantisera and complement by using a microcytotoxicity assay. Chimeras showed no clinical signs of graft-vs-host disease (GVHD). TLI-treated mice seemed to show a slightly accelerated onset of lymphosarcoma as compared with untreated controls, but the difference was not significant (p = 0.08). BALB/c leads to B/W F1 chimeras reconstituted at 1 to 3 mo of age (25 mice) developed no tumors for an observation period of 18 mo after transplantation. In contrast, tumors developed in 24/130 of age-matched controls, and in 13/57 of TLI-treated nonreconstituted age-matched B/W F1 mice. Tumor incidence in BALB/c leads to B/W F1 chimeras transplanted at an older age (9 to 11 mo) was similar to that observed in age-matched TLI-treated B/W F1 mice and age-matched untreated controls. The data suggests that the high naturally occurring incidence of lymphosarcoma could be reversed by reconstituting TLI-treated mice with BM cells (p = 0.027). Thus, allogeneic BM transplantation may exert potent graft-vs-tumor effects (GVT) when tumor susceptible hosts are reconstituted at an early age, whereas GVT is relatively ineffective at an advanced age, which probably correlates with an advanced stage of tumor development. Allogeneic BM transplantation should be additionally explored as a potential clinical tool for eradication of certain solid tumors in adjunct to high-dose radiochemotherapy, inasmuch as GVT seems to be independent of GVHD.     

Different subsets of T cells in the adult mouse bone marrow and spleen induce or suppress acute graft-versus-host disease.

Fractionation of normal adult mouse spleen and bone marrow cells (C57BL/Ka) was performed by discontinuous Percoll density gradients. The fractionated low density (1.050-1.060 g/ml) C57BL/Ka spleen cells completely suppressed acute lethal graft vs host disease (GVHD) when coinjected with unfractionated C57BL/Ka spleen cells into sublethally irradiated (400 rad) BALB/c mice. In dose response experiments, as few as 0.5 x 10(6) low density cells from the spleen fractions suppressed acute GVHD induced by 2.5 x 10(6) unfractionated allogeneic spleen cells. Although the low density spleen fractions inhibited acute GVHD, the high density (1.075-1.090 g/ml) spleen fractions induced acute GVHD in sublethally irradiated BALB/c recipients. Fractionation of C57BL/Ka bone marrow cells showed that none of the high or low density fractions or unfractionated cells induced lethal GVHD. When these fractions were tested for their capacity to suppress GVHD by coinjection with C57BL/Ka unfractionated spleen cells, all fractions protected the BALB/c recipients. Unfractionated bone marrow cells showed modest protection. Evaluation of the dose response characteristics of the suppressive activity of the low and middle density (1.060-1.068 g/ml) bone marrow cell fraction showed that reproducible protection could be achieved at a 5:1 ratio of inducing to suppressing cells. The low density fractions of both bone marrow and spleen cells had a marked depletion of typical TCR(+)-alpha beta CD4+ or CD8+ T cells, and a predominant population of TCR(+)-alpha beta CD4- CD8- T cells. Purified populations of the latter cells suppressed GVHD. Recipients given unfractionated C57BL/Ka spleen cells and protected with low-density bone marrow or spleen cells were chimeras.     

Induction and mechanism of tolerance to bovine serum albumin in mice given total lymphoid irradiation (TLI).

BALB/c mice given total lymphoid irradiations (TLI) were injected i.p. with bovine serum albumin (BSA) in saline, and challenged with DNP-BSA in complete Freund's adjuvant 6 weeks later. The latter animals made no anti-DNP antibody response as measured by a modified Farr assay, but made a normal anti-DNP response after challenge with DNP-BGG in adjuvant. Normal mice or mice given whole body irradiation were not tolerized by the i.p. injection of BSA in saline. Spleen cells from unresponsive mice (TLI + BSA in saline) suppressed the adoptive secondary anti-DNP response of sublethally irradiated syngeneic hosts given BSA-primed T cells, DNP-BSA-primed B cells, and DNP-BSA in saline. The suppressor cells were antigen specific, and were inactivated by in vitro treatment with anti-Thy 1.2 antiserum and complement. The findings suggest that soluble antigens administered to mice after TLI evoke a state of tolerance that is maintained by antigen-specific suppressor T cells. A similar mechanism may be involved in the maintenance of tolerance to allografts. These findings may have important clinical implications for patients treated with TLI for lymphoid malignancies.     

Mechanism of neonatal idiotype suppression. II. Alterations in the T cell compartment suppress the maturation of B cell precursors

The cellular mechanism in neonatally suppressed BALB/c mice, which maintains the chronic suppressed state of the TEPC-15 idiotype in the antibody response to phosphorylcholine (PC), was investigated. Cells taken from these suppressed mice cannot transfer suppression to adult BALB/c or affect the in vitro response to PC of adult BALB/c spleen cells. However, spleen cells or T cells from neonatally suppressed mice given to neonatal animals induce chronic suppression of the TEPC-15 idiotype in the anti-PC response. Co-transfer of T cells from neonatally suppressed cells with normal T cells prevented the induction of suppression in neonates. Transfer of T cells from normal or keyhole limpet hemocyanin-primed BALB/c increased the expression of TEPC-15 idiotype in chronically suppressed mice, whereas T cells from neonatally suppressed were ineffective. These findings show that T cells in neonatally suppressed mice can affect the development of immature but not mature cells. The restoration of TEPC-15 expression in neonatally suppressed animals by normal T cells and the failure to induce suppression in neonates by co-transfers of T cells from normal and chronically suppressed mice demonstrate the profound role of an altered T cell compartment in sustaining chronic idiotype suppression.     

Defective isotype-specific regulation of IgA anti-erythrocyte autoantibody-forming cells in NZB mice

B cell hyperactivity characterizes many autoimmune diseases. In NZB mice this is manifested by a variety of immunologic aberrations, including increased B cell proliferation and hyper IgM and IgA secretion in vitro. Recent studies have shown that IgA secretion can be suppressed or enhanced in an isotype-specific manner by a soluble factor(s), called IgA-binding factor (IgABF), produced by IgA FcR-bearing T cells. We now show that T cells from young NZB mice, cultured with high concentrations of IgA, produce an IgABF that has aberrant biologic activity when compared to IgABF produced from IgA FcR+ T cells of BALB/c mice. Although BALB/c IgABF normally suppresses proliferation and secretion by IgA-producing B cells, neither proliferation nor IgA secretion from normal murine IgA-B cells is suppressed by NZB IgABF. In fact, IgA secretion is significantly enhanced by NZB IgABF. We also present the first evidence of IgA anti-mouse erythrocyte (anti-MRBC) autoantibody-forming cells present in the spleens of NZB mice. Whereas BALB/c IgABF suppresses the in vitro generation of IgA anti-MRBC autoantibody-forming cells by NZB spleen cells, NZB IgABF enhances this response. Of particular interest is the development of IgA anti-MRBC autoantibody-forming cells in cultures of spleen cells from nonautoimmune BALB/c mice in the presence of NZB IgABF. These studies suggest that isotype-specific T cells factors might play an important role in the development of autoantibody-forming cells.     

Cutaneous leishmaniasis in anti-IgM-treated mice: enhanced resistance due to functional depletion of a B cell-dependent T cell involved in the suppressor pathway

The contribution of B cells and antibodies to either the resistance or susceptibility to cutaneous leishmaniasis has been investigated in mouse strains rendered B cell-deficient by treatment with anti-mouse IgM antisera from birth (mu-suppressed). These studies confirm that immunity to cutaneous disease in a normally resistant mouse strain (C3H/HeJ) is independent of antibody, but that B cells and/or antibodies are required for the evolution of suppressed DTH and the consequent disease susceptibility of BALB/c mice. Anti-IgM-treated BALB/c mice, which lacked detectable anti-leishmanial antibodies during the course of infection, displayed a sustained DTH response to leishmanial antigen and were able to control their cutaneous lesions. The enhanced resistance of mu-suppressed mice could be completely abrogated by transfer of suppressor T cells from infected control animals into mu-suppressed mice before their infection. Thus the suppressor T cells, which are generated during leishmanial infection in BALB/c mice, can effect suppression in the absence of antibody. Evidence that B cells or antibodies are required for the generation of suppressor T cells was demonstrated by using BALB/c mice in which suppressor T cells fail to be generated during infection as a result of prior sublethal irradiation. Splenic T cells from normal mice could overcome the resistance conferred by sublethal irradiation, whereas splenic T cells from mu-suppressed mice could not. Thus the enhanced resistance of mu-suppressed BALB/c mice appears to be a consequence of their lack of functional expression of a B cell-dependent T cell critical to the suppressor pathway.     

Suppression of pokeweed mitogen-stimulated immunoglobulin production in patients with rheumatoid arthritis after treatment with total lymphoid irradiation

Patients with intractable rheumatoid arthritis (RA) were treated with total lymphoid irradiation (TLI, 2000 rad). We previously reported long-lasting clinical improvement in this group associated with a persistent decrease in circulating Leu-3 (helper subset) T cells and marked impairment of in vitro lymphocyte function. In the present experiments, we studied the mechanisms underlying the decrease in pokeweed mitogen stimulated immunoglobulin (Ig) secretion observed after TLI. Peripheral blood mononuclear cells (PBL) from TLI-treated patients produced 10-fold less Ig (both IgM and IgG) in response to pokeweed mitogen than before radiotherapy. This decrease in Ig production was associated with the presence of suppressor cells in co-culture studies. By using responder cells obtained from normal individuals (allogeneic system), PBL from eight of 12 patients after TLI suppressed Ig synthesis by more than 50%. In contrast, PBL from the same patients before TLI failed to suppress Ig synthesis. Suppression by post-TLI PBL was also demonstrated in an autologous system by using responder cells cryopreserved before TLI. Again, only cells obtained after TLI were suppressive in four of seven patients. PBL with suppressive activity contained suppressor T cells, and the latter cells bore the Leu-2 surface antigen. In 50% of the patients studied, suppressor cells were also found in the non-T fraction and were adherent to plastic. Interestingly, the Leu-2+ cells from TLI-treated patients were no more potent on a cell per cell basis than purified Leu-2+ cells obtained before TLI. Additional experiments suggested that the suppression mediated by T cells after TLI is related to the increased ratio of Leu-2 to Leu-3 cells observed after radiotherapy.     

The repertoire diversity and magnitude of antibody responses to bacterial antigens in aged mice: I. Age-associated changes in antibody responses differ according to the mouse strain

Aging influences the host immune responses in various ways. In aging mice we have studied the antibody responses to two unrelated bacterial antigens. Streptococcus pneumoniae R36a vaccine (Pn) and TNP coupled to Brucella abortus (TNP-BA). Aged animals (20-24 months old) of the C57BL/6 strain had markedly reduced numbers of IgM antibody plaque-forming cells (PFC) to Pn as compared to young/adult mice (2-3 months old). In contrast, the anti-Pn IgM PFC responses of aged BALB/c mice were consistently higher than they were in the young/adult mice. The increased anti-Pn responses were not due to a nonspecific immunostimulation, because the responses of aged BALB/c mice to TNP-BA were lower as compared to the adults. However, the aged BALB/c mice responded relatively poorly to Pn challenge, and their IgG responses (as determined by ELISA plaque assay) demonstrated a very high individual variability. The clonotypic diversity of anti-Pn response in young BALB/c and C57BL/6 is limited, such that the majority of PFC produce antibody that express all idiotopes (Id) of the T15 immunoglobulin encoded in the VH-S107/Vk22 genes. In contrast, the PFC from aged mice are diverse, expressing incomplete T15 Id or none at all, suggesting that the antibodies are encoded by altered T15 genes and by different, non-T15 genes. Our data demonstrate that the age-related changes in the magnitude of antibody response to certain antigens are influenced by the host genetic make-up, and that the changes in magnitude and diversity of antibody response may be unrelated to each other.     

A partial characterization of suppressor cells in the spleens of mice conditioned with fractionated total lymphoid irradiation (TLI)

Total lymphoid irradiation (TLI) is a highly effective modality for inducing immunosuppression and transplantation tolerance. The cellular basis for this immunosuppression is not clear, although T cells have been implicated. To study further the effect of TLI on the immune system, we have examined the B cells and suppressor cells in the spleens from TLI-conditioned mice. Our results indicate that after TLI, the spleen is rapidly repopulated with many large, immature cells. The probable source of these cells is the shielded bone marrow (BM). The B cells from TLI-conditioned mice are transiently immature and hyporesponsive in vitro to a T-independent antigen. Spleen cells from TLI-conditioned mice nonspecifically suppress the in vitro T-independent anti-TNP response of normal B cells. The suppressor cells lack both B and T cell markers and adhere to Sephadex G-10. The suppressor cells in spleens from TLI-treated mice bear a number of similarities to those present in normal BM. When normal BM cells were analyzed by indirect immunofluorescence for the presence of the Mac-1 antigen, two populations of suppressor cells could be identified: one was Mac-1+ and the other was Mac-1-. These data are consistent with the possibility that a subpopulation of the suppressor cells found in normal BM and in the spleens from TLI-conditioned mice are immature cells of the monocytic/granulocytic lineage.     

A monoclonal antibody that recognizes an Ly-6-linked antigen inhibits the generation of functionally active T cell subsets

A monoclonal antibody (mAb) generated against the chemically-induced BALB/c Meth A sarcoma, designated HD42, reacts in cytotoxic tests with Meth A as well as with BALB/c peripheral lymph node cells and mitogen-activated spleen cells. The antigen was detected by FACS analysis on BALB/c spleen and lymph node cells, and by absorption assays on all normal lymphoid cells of BALB/c but not B6 mice. The expression of the antigen was not found on normal adult lung fibroblasts, on brain, nor on an extensive panel of tumors of BALB/c and B6 origin. Because the strain distribution of the antigen is reciprocal to that of Ly-6.2 and is not expressed in congenic C3H.Ly-6b mice, we have tentatively defined it as Ly-6.1 and referred to the mAb as alpha-Ly-6.1. The presence of alpha-Ly-6.1 abrogates both the Con A-induced and the IL 2-dependent proliferative response of normal T cells, whereas the response of normal B cells to LPS remains unaffected. alpha-Ly-6.1 is a potent suppressor of the primary in vitro plaque-forming cell (PFC) response to SRBC. Pretreatment of normal splenic T cells with alpha-Ly-6.1 and complement had no effect on the ability of these cells to generate in vitro either T helper cells (TH) or T suppressor cells (TS) to SRBC. However, addition of antibody in the absence of complement during the generation of TH or TS, or posttreatment of these T cell subsets with antibody and complement after in vitro education, completely removed the functional activity of these cell types. Addition of alpha-Ly-6.1 to MLC suppressed the MLR as well as the generation of cytotoxic lymphocytes (CTL), whereas the presence of the antibody during a cell-mediated lympholysis (CML) had no effect. Therefore, it appears that alpha-Ly-6.1 recognizes an antigen that is important for the generation of TH and TS cell subsets.     

Immunological basis for susceptibility and resistance to pulmonary blastomycosis in mouse strains

The immunological basis for a >10-fold resistance of outbred CD-1 mice compared to inbred BALB/c mice to pulmonary blastomycosis was investigated. Bronchoalveolar macrophages (BAM) from CD-1 mice killed yeast cells of Blastomyces dermatitidis (Bd) by 25% and this increased to 59% when activated by IFN-gamma. In contrast, BAM from BALB/c mice lacked significant killing (5%) of Bd but could be activated by IFN-gamma for enhanced killing (19%). Peritoneal macrophages (PM) from CD-1 mice had significant fungicidal activity for Bd (43%) and this increased to 63% with IFN-gamma treatment. By contrast, PM from BALB/c mice did not significantly kill Bd (14%) but were activated by IFN-gamma for significant killing (24%). Fungicidal activity of peripheral blood polymorphonuclear neutrophils (PMN) from CD-1 (87%) was greater than that of BALB/c (75%) (P<0.05). Macrophage inflammatory protein-1alpha (MIP-1alpha) production by BAM from BALB/c was significantly less than that from CD-1 in response to co-culture with Bd. IFN-gamma production by CD-1 spleen cells in response to concanavalin A (Con A, 1microg/ml) was 8-fold greater than that by BALB/c spleen cells. In contrast, BAM and PM from BALB/c mice in co-culture with Bd secreted several-fold more TNFalpha than BAM or PM from CD-1 mice. IL-2 production by BALB/c spleen cells in response to Con A was 3- to 4-fold greater than that by CD-1 spleen cells. Depressed IL-2 production by Con A stimulated CD-1 spleen cells correlated with depressed proliferative responses. Resistance of CD-1 mice to pulmonary blastomycosis correlates with enhanced fungicidal activity of BAM, PM, PMN, and IFN-gamma production by Con A stimulated spleen cells, compared to BALB/c mice. Consistent with the in vitro enhancement of effector cell function by IFN-gamma, in vivo therapy with IFN-gamma significantly (P<0.0001) improved survival of BALB/c mice with pulmonary blastomycosis.     

Induction of T15-specific suppressor T cells in mice with the CBA/N defect by neonatal injection with anti-T15 idiotype antibody

Mice with the CBA/N defect (xid) are unresponsive to phosphorylcholine (PC), To determine whether idiotype-specific suppressor T cells can also be generated in these defective mice, defective (CBA/N X BALB/c)F1 male and nondefective (CBA/N X BALB/c)F1 female or (BALB/c X CBA/N)F1 male mice were neonatally injected with antibodies specific for the major idiotype of anti-PC antibody, i.e., anti-TEPC-15 idiotype (T15id) antibody. Suppressor cell activity was examined by co-culturing spleen cells from neonatally treated F1 mice with spleen cells of normal nondefective F1 mice in the presence of antigen. Spleen cells from defective (CBA/NM X BALB/c)F1 mice treated with anti-T15id antibody demonstrated a level of suppressor activity (greater than 83% suppression) comparable to that of similarly treated nondefective F1 mice. This suppression was specific for the T15id of anti-PC response, and a Lyt-1-2+-bearing T cell population appeared to be responsible for the active suppression. These suppressor T cells recognized T15 but not PC, based on a functional absorption test. These results indicate that the CBA/N defects, including the deficiency in the anti-PC response by B lymphocytes and a possible T cell defect, do not influence the generation of T15id-specific suppressor T cells by neonatal injection with anti-T15id antibody.     

Effect of passive administration of alloantiserum containing antibody against putative acceptor(s) for T cell-replacing factor (TRF) in the neonatal stage on development of B cell activity responsive to TRF

Previously, we showed that the antiserum raised in male (DBA/2Ha X BALB/c)F1(DCF1) mice (T cell-replacing factor [TRF]-low response animals) by immunizing them with activated B cells from BALB/c mice (TRF-high-responders) contained antibodies against putative TRF-acceptor site(s). We have now evaluated the hypothesis that neonatal treatment of mice with the above antiserum suppresses the development of B cells responsive to TRF. Male DCF1 mouse anti-BALB/c B-cell antiserum or normal DCF1 mouse serum as a control was injected into BALB/c mice within 24 hr after birth. In the antiserum-treated mice, no augmented primary immunoglobulin M (IgM) antibody responses to sheep red blood cells (SRBC) were observed under the conditions in which markedly augmented IgM anti-SRBC responses were induced in control BALB/c mice, suggesting that development of B cells reacting with male DCF1 mouse anti-BALB/c B-cell antiserum is suppressed by the neonatal treatment with the antiserum. Furthermore, the development of B cell activity responsible for helper factors derived from T cells, such as TRF, was markedly suppressed in the neonatally antiserum-treated mice, whereas activity of B cells capable of interacting directly with helper T cells through antigen-bridges was not significantly affected by the same treatment. Such suppression of the B cell activity could be induced only when the antiserum was administered within 48 hr after birth. Moreover, neonatal treatment of mice with the antiserum induced suppressed responsiveness of B cells to a T-independent type 2 antigen, TNP-Ficoll. Neither serum-borne suppressive serum components nor suppressor cells were detected by the system employed. These results support the hypothesis that TRF responsive B cells constitute a subpopulation distinct from the other B cells capable of cooperating with helper T cells via cognate interaction.