The cellular lesion responsible for exaggerated IgE synthesis accompanying allergic breakthrough

Appropriate levels of IgE are maintained by a cellular and molecular network composed of (1) a suppressive, Ly-1+, CD4+ T cell-dependent arm that is activated by inappropriate high levels of IgE and (2) an enhancing, CD8+ T cell-dependent arm that controls this suppression in a feedback regulatory manner. Ly-1+ T cells also function to counterbalance (inhibit) the activity of these latter CD8+ T cells. It has been previously shown that Ly-1+ T cells can reverse low-dose irradiation-induced enhancement of IgE antibody responses (i.e., allergic breakthrough). We have analyzed lymphocytes isolated from mice subjected to low-dose irradiation to determine which component of this network is defective in such animals. Stimulation of normal lymphocytes with IgE in vitro resulted in the release of lymphokines that suppress IgE antibody responses. In contrast, similar stimulation of lymphocytes from irradiated mice did not elicit secretion of such suppressive lymphokines, unless the cells were depleted of CD8+ T cells or reconstituted with normal Ly-1+ T cells. Because Ly-1+ T cells of irradiated mice could not reconstitute the response, we conclude that this functional subset of CD4+ T cells, which normally controls CD8+ T cell activity in this network, is defective in animals that exhibit irradiation-induced allergic breakthrough.     

Activation of distinct helper and suppressor T cells in experimental trypanosomiasis.

Spleen cells taken from mice soon after infection with Trypanosoma brucei S 42 enhance the primary in vitro antibody response of normal spleen cells to sheep red blood cells (SRBC), but do not affect their response to DNP-Ficoll. Spleen cells harvested later in the infection (day 6 onwards) suppress the antibody response of normal spleen cells to both SRBC and DNP-Ficoll. The enhancing and suppressive effects of "infected" spleen cells are sensitive to treatment with anti-Thy 1.2 anti-serum and complement, and can be mediated by nylon wool-purified populations of T cells. The enhancing T cell is sensitive to ALS, not lost within 4 weeks of adult thymectomy, and bears the Ly-1+, 23- phenotype. The suppressor T cell is insensitive to ALS, lost within 20 weeks of adult thymectomy, and bears the Ly-1+, 23+ phenotype. The significance of the activation of distinct helper and suppressor T cells is discussed in relation to the pathogenesis of trypanosomiasis.     

Suppression of IgE antibody production in SJL mice. V. Effect of irradiation and adult thymectomy on the suppression of IgE antibody production in SJL mice

Anti-DNP IgE antibody production was low and transient in SJL mice which were immunized with 1 microgram DNP-Nb and 1 mg A1(OH)3. The immunized SJL mice were irradiated (60-540 R) 1 day after challenge. A dose higher than 180 R induced enhancement of anti-DNP IgE antibody production as compared to nonirradiated control mice, suggesting the existence of irradiation-sensitive suppressor cells. Anti-DNP IgE antibody production was suppressed when immunized and irradiated SJL mice were injected with spleen cells from adult-thymectomized SJL mice. The donors of the spleen cells were thymectomized 2 or 4 months previously, and this suggests that the suppressor cells from unprimed mice are long-living T cells.     

Reaginic antibody formation in the mouse. VII. Induction of suppressor T cells for IgE and IgG antibody responses.

Intravenous injections of urea-denatured ovalbumin (UD-OA) into OA-primed high responder mice suppressed the antibody response not only to the priming antigen but also to subsequent immunization with dinitrophenyl derivatives of OA (DNP-OA). The transfer of normal spleen cells or OA-primed spleen cells into UD-OA-treated animals did not restore the capacity of responding to DNP-OA to form anti-DNP IgE and IgG antibodies. The transfer of splenic T cell fraction from the UD-OA-treated animals into normal syngeneic mice diminished both IgE and IgG antibody responses of the recipients to DNP-OA. The B cell-rich fraction from the same donors failed to affect the anti-hapten antibody response and enhanced anti-cancer (OA) IgG antibody response of the recipients. It was also found that the transfer of T cell-rich fraction of OA-primed spleen cells failed to suppress antibody response of the recipients to DNP-OA. The results indicated that spleen cells of UD-OA-treated mice contained suppressor T cells which are distinct from helper cells. Suppressive activity of T cells in the UD-OA treated animals was specific for OA. The transfer of the T cell-rich fraction failed to suppress anti-DNP antibody response of the recipients to DNP-KLH.     

Trypanosoma cruzi-induced suppression of IL-2 production. II. Evidence for a role for suppressor cells

Suppression of IL-2 production during experimental Chagas' disease accounts at least in part for the overall depressed state of the immune system in infected mice. The failure to produce IL-2 in response to mitogen stimulation is not the result of the lack of cells capable of producing IL-2, but appears to be due to regulation of IL-2 production by suppressor cells. This conclusion is supported by cell-mixing experiments where the ability of cells from infected mice to suppress normal spleen cell IL-2 production is evident. Although depletion of plastic and Sephadex G-10 adherent cells results in modest increases in IL-2 production by spleen cells from infected mice, even in the presence of normal adherent cells as a source of IL-1 producers, IL-2 production does not approach normal levels. Also, isolated macrophages are not by themselves suppressive for normal spleen cell IL-2 production, whereas plastic and G-10 nonadherent cells from infected mice are. Depletion of Thy-1+ and Ly-2+ cells not only completely abrogates the ability of spleen cells from infected mice to suppress normal IL-2 production, but results in a cell preparation which actually enhances IL-2 production. Anti-Ly-2 and C treatment of infected spleen cells also markedly enhances their ability to produce IL-2. These results indicate a major role for Ts cells in the regulation of IL-2 production, and a relatively minor role of macrophages as direct effector cells of suppression in this response. The ability to enhance IL-2 production in this system with PG synthesis inhibitors suggests a role for PG-producing cells such as macrophages in the suppressor mechanism, perhaps as inducers of the suppressor effector cells.     

Suppressor T cells and self-tolerance. Active suppression required for normal regulation of anti-erythrocyte autoantibody responses in spleen cells from nonautoimmune mice

Spleen cells from young, nonautoimmune strains of mice cultured with syngeneic E do not develop a significant anti-mouse E response in vitro, consistent with a state of self-tolerance to this Ag. In order to study the role of active suppression in regulating mouse RBC-(MRBC) specific cells in nonautoimmune cell populations, the effect of depleting T cell subsets on the generation of anti-MRBC autoantibodies by nonautoimmune spleen cells was determined. Spleen cells from young BALB/c and C57BL/6 mice were found to generate significant numbers of IgM and IgG anti-MRBC autoantibody-forming cells in culture with MRBC after depletion of Ly-2+ cells by anti-Ly-2 and C treatment. The response which develops is Ag dependent, Ag specific, and dependent upon L3T4+ Th. The magnitude and isotype of this response is similar to the anti-MRBC response generated by spleen cells from 12-mo-old, autoimmune NZB mice and young NZB mice also treated to remove Ly-2+ cells. Addition of isolated Ly-2+ T cells, but not L3T4+ or Ly-2- T cells, to spleen cells depleted of Ly-2+ cells restores apparently normal regulation of the anti-MRBC response in vitro. These data demonstrate that control of a specific autoantibody response to MRBC by nonautoimmune spleen cell populations requires active regulation by an Ly-2+ T cell subset.     

IgE formation and Fc receptor-positive lymphocytes in normal, immuno-deficient, and auto-immune mice infected with Nippostrongylus brasiliensis

The IgE serum levels and IgE FcR-positive lymphocytes (Fc epsilon R) in the spleen and mesenteric lymph nodes (MLN) of normal and immunologically mutant strains of mice were determined before and 14 days after infection with Nippostrongylus brasiliensis (Nbr) parasites. By IgE rosetting of cells immunofluorescently stained for sIg. Thy-1.2, Lyt-2, and L3T4, only sIg+ IgE rosetting lymphocytes were detected in both normal and Nbr-infected mice. IgE high responder mice had the same percentage of Fc epsilon R+ spleen and MLN lymphocytes as low responder mice. After Nbr infection, the percentages of splenic and MLN Fc epsilon R+ cells increased in parallel to a similar increase of sIg+ B cells. Athymic C57BL/6J-nu mice had 62% Fc epsilon R+ spleen and 85% Fc epsilon R+ MLN cells before and after Nbr infection, but IgE serum levels were less than 5 ng IgE/ml. C57BL/6J mice with the viable moth-eaten mutation mev which have almost exclusively Ly-1+ B cells, had less than 1% Fc epsilon R+ lymphocytes and formed only small amounts of IgE. C57BL/6J mice with the lymphoproliferation (lpr) or generalized lymphoproliferative disease (gld) mutations had low numbers of Fc epsilon R+ cells but formed 15 to 30 times more IgE after Nbr infection than control C57BL/6J mice. The IgE response of mice with the beige mutation (bg) did not differ from control mice. Mice with the xid mutation had few Fc epsilon R+ and sIg+ cells but showed high IgE responses. These data demonstrate that Fc epsilon R are typical cell surface markers for approximately 90% of murine Ly-1-, sIg+ B cells and that the number of Fc epsilon R+ cells does not correlate with the capacity of the mice to form IgE. The IgE response to Nbr infection is normal in mice homozygous for the bg mutation, elevated in mice homozygous for the xid, lpr, and gld mutations, and decreased in mice homozygous for the mev and nu mutations.     

Investigations into the nature of Igh-V region-restricted T cell interactions by using antibodies to antigens on methylcholanthrene-induced sarcomas. I. Analysis of an Igh-V-restricted suppressor-inducer factor

We have previously demonstrated the relationship between antigens on BALB/c methylcholanthrene (MC)-induced fibrosarcomas and T cell regulatory molecules by using a variety of antisera raised to these sarcomas in BALB/c and BALB/c X C57BL/6 (CB6F1) mice. One such pool of antiserum, a CB6F1 anti-CMS 4 (Pool XIV) serum, was used to investigate the nature of the T cell regulatory structures recognized by these antibodies. Pool XIV antiserum was capable of blocking the induction of feedback suppression by Ly-1 TsiF, an SRBC-specific suppressor T cell factor secreted by Ly-1+, 2- I-J+ T cells. Ly-1 TsiF induces suppression by interacting with an Ly-1+,2+ I-J+ T cell target. Successful interaction of Ly-1 TsiF with its target cell requires genetic homology between inducer and target cells at the variable region of the immunoglobulin heavy chain gene complex (Igh-V). The addition of Pool XIV antiserum to primary in vitro anti-SRBC cultures resulted in blocking the ability of Ly-1 TsiF from Igha (BALB/c) and Ighj (CBA/J) mice to induce suppression on syngeneic cells, whereas suppression induced by Ly-1 TsiF in Ighb (B6), Ighc (DBA/2), Ighd (A/J), and Ighe (AKR) mice are unaffected by addition of the Pool XIV antiserum. The ability of Pool XIV antiserum to block Ly-1 TsiF activity is linked to the Igh region, because Pool XIV antiserum can block Ly-1 TsiF from BALB/c (H-2d, Igha) and the Igh congenic B.C9 (H-2b, Igha) while not affecting Ly-1 TsiF activity on B6 (H-2b, Ighb) or its Igh congenic C.B20 (H-2d, Ighb). In CB6F1 animals, Pool XIV antiserum could block the ability of CB6F1 Ly-1 TsiF to suppress BALB/c spleen cells but not B6 spleen cells. Conversely, Pool XIV antiserum could block the ability of BALB/c Ly-1 TsiF to suppress CB6F1 spleen cells, whereas B6 Ly-1 TsiF showed normal suppressive activity in the presence of Pool XIV antiserum. In contrast, Pool XIV was capable of blocking the ability of Ly-1 TsiF from BALB/c into CB6F1 bone marrow chimeras (BMC) to suppress both BALB/c and B6 mice, whereas the activity of Ly-1 TsiF from B6 into CB6F1 BMC on BALB/c or B6 spleen cells was unaffected by the addition of Pool XIV antiserum. We then investigated the molecular nature of the molecule recognized by Pool XIV antiserum on the Ly-1 TsiF.(ABSTRACT TRUNCATED AT 400 WORDS)     

Characterization of SJL T cell clones responsive to syngeneic lymphoma (RCS): RCS-specific clones are stimulated by activated B cells

To gain insight into the nature of the syngeneic T cell-stimulating molecules on SJL lymphoma cells (RCS), a panel of eight Ly-1+2- T cell clones that are specific for transplantable RCS has been generated. All of these clones proliferate vigorously in response to two independent RCS lines and to LPS-activated syngeneic or F1 B cell blasts, but not to unstimulated SJL spleen cells or to allogeneic B cell blasts. Only one RCS-specific clone displays a proliferative response to (SJL X BALB/c) resting spleen cells, suggesting that I-E molecules are not the source of stimulation of RCS-responsive cells. Responses of the T cell clones to both RCS and syngeneic LPS-activated B cells are inhibited by monoclonal antibodies to I-A antigens, and not by antibody to I-E antigens. These findings suggest that RCS-responsive T cells are stimulated either by syngeneic I-As alone, in a form expressed on activated B cells, or by I-As in combination with X, where X is a cell surface antigen present on B cells at certain stages of differentiation.     

Hapten-specific IgE antibody responses in mice. VII. Conversion of IgE "non-responder" strains to IgE "responders" by elimination of suppressor T cell activity.

Mice of the inbred strains SJL (H-2s) and AKR (H-2k) are "non-responders" and "low-responders," respectively, in terms of their capacity to develop antibody responses of the IgE class when immunized with conventional proteins and hapten-protein conjugates under conditions optimal for eliciting IgE responses in "high-responder" mice, such as BALB/c (H-2d), to these same antigens. For example, BALB/c mice preimmunized with ASC and then challenged 7 days later with DNP-ASC develop peak augmented primary IgE anti-DNP antibody responses of 320 PCA units, whereas SJL and AKR mice develop responses which are 16-fold and 4-fold lower, respectively. However, pretreatment of the latter two strains with appropriate doses of either x-irradiation (150 R), cyclophosphamide (100 mg/kg) or ALS (150 mul) before carrier-preimmunization strikingly enhances the magnitude of IgE antibody responses in such mice to levels as high as 64-fold above those of untreated control mice of the same strains. Evidence obtained in these experiments indicates that the capacity of such maneuvers to to convert poor IgE responders to high responder status reflects elimination of nonantigen-specific suppressor T lymphocytes which are naturally present and normally function to suppress or "dampen" the IgE antibody response in a relatively selective manner. It appears that these cells modulate IgE responses by acting at least at two distinct points: 1) The most effective activity seems to be at the level of induction of carrier-specific helper T cells; 2) A second locus of inhibitory activity is more distal in the response, either impeding helper T cell-B cell cooperative interactions or suppressing B cell differentiation and/or function directly. Taken collectively, these observations demonstrate that the state of poor responsiveness of the SJL and AKR strains for the IgE antibody class is not a reflection of a genetic inability to develop IgE responses but rather a manifestation of a genetic capability to actively inhibit IgE antibody synthesis.     

Germinal center cells are a major IL-5-responsive B cell population in peripheral lymph nodes engaged in the immune response

Germinal center formation and the development of B cell memory in lymphoid tissue is a T cell-dependent process. The specific B cell-T cell interactions, and/or cytokines, resulting in germinal center cell growth have not yet been identified. Germinal center B cells were separated from other lymph node (LN) B cells by panning on peanut agglutinin (PNA)-coated dishes. Resulting fractions enriched for PNA+ (germinal center) B cells, and the PNA- (other) LN B cells from immune SJL mice were assayed for proliferation in the presence of cytokines. PNA+ and PNA- B cells responded equally to IL-4 in the anti-mu co-stimulator assay. In contrast, PNA+ B cells responded to murine (r)IL-5 or human B cell growth factor in the dextran sulfate (DxS) co-stimulator assay, to a much greater degree than did PNA- B cells. The same results were obtained with PNA+ and PNA- cells from LAF1 mice. Unfractionated LN B cells from nonimmunized SJL or BALB/c mice did not respond to IL-5 with or without DxS. B cell populations from BALB/c mice such as from spleen and peritoneal cavity, which are known to be high in Ly-1+B cells, responded to IL-5 alone, and more dramatically, to IL-5 as a co-stimulator with DxS. Such populations of cells from SJL mice, which are known to contain low numbers of Ly-1+B cells, responded markedly less. These results are consistent with those of others which show that in nonimmunized mice, Ly-1+B cells are a major IL-5 responsive subpopulation. IL-1 enhanced the proliferation of PNA+ cells in response to rIL-5 and had no effect on PNA- cells. IL-4 and IL-5 did not enhance each other's effects as co-stimulators of proliferation. In contrast to PNA+ B cells from immune LN, B cells activated by Escherichia coli endotoxin exhibited no responses to rIL-5. The present results indicate that in immune LN, PNA+, germinal center B cells constitute a prominent IL-5-responsive population.     

Characterization of the immunodeficiency of RIIS/J [corrected] mice. I. Association with the CD5 (LY-1) [corrected] B cell lineage

RIIIS/J mice produce low antibody responses to several polysaccharide Ag of bacterial origin. They have low levels of serum IgM and IgG3 and high levels of serum IgG2a and IgG2b. Low serum IgM and IgG3 have been attributed to a low frequency of CD5 (Ly-1) B cells, which play an important role in the production of natural antibodies. Indeed, RIIIS/J mice have a low frequency of CD5 (Ly-1)+, IgM bright+, Ly-5 (B220)dull+ (i.e., CD5 (Ly-1) B) cells in their peritoneum. RIIIS/J mice treated with LPS produce a low anti-bromelain-treated mouse RBC splenic plaque-forming cell response and a normal anti-mouse transferrin splenic PFC response. Those data are compatible with the fact that CD5 (Ly-1) B cells contain the precursors of B lymphocytes secreting anti-bromelain-treated mouse RBC antibody. However, they have a higher frequency of IgM bright+, Mac-1+ cells in their peritoneum. These cells represent the CD5 (Ly-1) "sister population" of CD5 (Ly-1) B cells described by others. This suggests that characteristics usually associated with the CD5 (Ly-1) lineage are applicable only to the CD5 (Ly-1)+ Mac-1+ IgM+ population, but not the related CD5 (Ly-1)- Mac-1+ IgM+ population. RIIIS/J mice should thus prove a valuable model to study the CD5 (Ly-1) B cell lineage.     

A CD4 cell is capable of transferring suppression of collagen-induced arthritis

Collagen-induced arthritis can be suppressed by i.v. injection of intact type II collagen (CII) but not type I collagen before immunization. To identify the mechanism mediating this suppression, splenocytes were obtained from mice injected with CII or OVA and administered to recipients that were subsequently immunized with CII. Mice receiving cells from donors injected with CII had a lower incidence of arthritis and lower antibody titers than those receiving cells from OVA-injected donors. Treatment of cells with 3000 rad of gamma-irradiation abrogated the suppression. To determine the phenotype of these donor cells, spleen cells were fractionated by adherence to plates coated with mouse anti-IgG to enrich for Thy-1+ phenotype. Thy-1+ cells injected into naive mice could significantly suppress arthritis. Further depletion of T cell subsets by panning revealed that depletion of CD4+ cells prevented the transfer of suppression whereas removal of CD8+ cells had no effect. Isolated CD4+ cells transferred into naive mice were also suppressive. Recently the Pgp-1 (Ly-24) Ag has been described to identify a unique memory subset of CD4+ cells when present on the cell surface. In CII-tolerized spleen populations, removal of the Pgp-1+ (Ly-24) subset of T cells abrogated suppression and transfer of isolated Pgp-1+ cells suppressed arthritis. These findings indicate that the Pgp-1+ subset of CD4+ cells can suppress collagen-induced arthritis and suggest that a CD4+ memory cell down-regulates autoimmunity. In addition, treatment of donor animals with cyclosporin, which inhibits the development of CD4+ cells, abrogated suppression.     

Isotype-like suppression of T cell-mediated immunity in vivo. II. Suppression of the early component of contact sensitivity by a Ly-2+ T cell-derived suppressor factor that binds to contact sensitivity-initiating, antigen-specific, Ly-1+ T cell-derived factors that are of different antigen specificities

Recognition that delayed-type hypersensitivity (DTH) reactions, such as contact sensitivity (CS) in mice, are initiated by Ly-1+ T cell-derived, antigen-specific factors has led to identification of a new kind of suppressor T cell that regulates this initiation phase of CS. Regulation by these suppressor T cells is T cell isotype-like in that initiation of DTH of various antigenic specificities is suppressed, whereas, Ly-1+ T cells mediating the antigen/major histocompatibility complex-restricted, classic delayed phase of CS responses are not affected, nor are other T cell activities. This study shows that these isotype-specific suppressor T cells probably act by release of soluble, isotype-specific, suppressor factors. These isotype-specific T cell factors bind to and can be eluted from columns linked with antigen-specific Ly-1+ T cell factors that initiate CS, and are of different antigen specificities. These T cell regulating, anti-isotypic suppressor factors are derived from Lyt-2+ I-J- T cells and suppress CS-initiating T cells, but do not affect the delayed-acting T cells of CS. This is in contrast with antigen-specific T cell suppressor factors that affect the late-acting and not the early-acting T cells of CS. It is suggested that the antigen-binding, CS-initiating, T cell factors, and their regulatory, anti-isotypic T cell factors are, respectively, T cell analogues of immunoglobulin(Ig)E antibody, and IgE-binding factors, that regulate IgE antibody production by IgE+ B cells.     

Generation of specific helper cells and suppressor cells in vitro for the IgE and IgG antibody responses.

Normal splenic lymphocytes from BDF1 mice were cultured on ovalbumin (OA)-bearing syngeneic peritoneal adherent cells for 5 days and their subsequent helper function was tested by an adoptive transfer technique. Lymphocytes harvested from the culture were mixed with DNP-KLH-primed spleen cells and transferred into irradiated syngeneic mice followed by challenge with DNP-OA. The results showed that the cultured lymphocytes has helper function for both IgE and IgG anti-DNP antibody responses. Depletion of mast cells and T cells in the peritoneal adherent cell preparations did not affect the generation of helper cells in the culture. The helper function of the cultured lymphocytes was abolished by the treatment with anti-theta antiserum and complement and was specific for ovalbumin. The OA-specific helper T cells were generated in vitro by the culture of a T cell-rich fraction of normal spleen on T cell-depleted OA-bearing peritoneal cells. If the normal splenic lymphocytes or T cell-rich fraction were cultured with 10 mug/ml of OA in the absence of macrophages, cultured lymphocytes lacked helper function. The transfer of splenic lymphocytes or splenic T cells cultured with soluble OA to normal non-irradiated mice, however, suppressed both IgG and IgE antibody responses of the recipients to subsequent immunization with DNP-OA. The suppressor cells were sensitive to anti-theta antiserum and complement and their activity was specific for OA. The cultured cells transferred into normal mice did not suppress anti-hapten antibody response to DNP-KLH. Normal lymphocytes cultured on OA-bearing macrophages and had helper function in adoptive transfer experiments failed to suppress antibody response of non-irradiated recipients to DNP-OA. The results indicate that OA-bearing macrophages primed T cells and generated helper T cells, whereas the culture of normal lymphocytes with soluble OA in the absence of macrophages generated suppressor T cells.     

Cellular immunity in chronic Theiler's virus central nervous system infection.

After (IC) inoculation of the DA strain of TMEV, SJL/J mice develop chronic CNS infection with marked mononuclear cell infiltration of spinal cord leptomeninges and white matter and concomitant demyelination. In the present study the temporal course of cell-mediated and humoral immune responses to virus were measured in this infection. It was shown that chronic TMEV infection is associated with the development of immunologically specific spleen cell reactivity as judged by in vitro incorporation of 3H-TdR into DNA in response to inactivated TMEV antigen. Spleen cell reactivity is first detectable about 2 months after infection, persists for at least 1 year, and correlates with the temporal development of serum-neutralizing antibody. The late development of sensitized spleen cells is not the result of an immunosuppressive effect of this virus infection since infected mice exhibit normal spleen cell proliferative responses to T cell mitogens and produce normal antibody responses to a heterologous protein antigen, sheep red blood cells. In addition, anti-viral antibody inhibits virus-induced spleen cell reactivity. Finally, the antigen-reactive lymphocyte subpopulation within the spleen responsible for proliferation to TMEV antigen are T cells and not B cells.     

Role of self carriers in the immune response and tolerance. IV. Active T cell suppression in the maintenance of B cell tolerance to a "T-independent" antigen.

Previous studies indicated that T cells are required for tolerance induction by hapten-modified syngeneic spleen cells (TNP-SC) in vivo. The role of T cells in the maintenance of this unresponsive state has been examined herein. By three criteria--limiting dilution precursor analysis, removal of T cells by anti-Thy-1 + C, and direct mixing experiments--we show that T cells are required for the continued suppression of the B cell response to the T-independent antigen, TNP-POL. Suppressor cells can also be induced by TNP-teratoma cells, which lack detectable H-2 antigens. Both anti-Ly-1 + C and anti-Ly-2 + C treatment reversed suppression induced by TNP-SC. These results demonstrate that normal B cell reactivity is present in the spleens of mice rendered tolerant by haptenated self, but that Ly-1,2,3 or Ly-1 + Ly-2,3 suppressor T cells prevent their responsiveness.     

Regulation of murine IgE production in SJA/9 and nude mice. Potentiation of IgE production by recombinant interleukin 4

Serum IgE levels were determined in different strains of mice with enzyme-linked immunosorbent assay by using rat monoclonal anti-murine IgE antibodies in normal and in Nippostrongylus brasiliensis-infected mice. After infection, serum IgE levels were high in BALB/c and CB-20, low in SJL/J and SJA/20 mice, and not detected at all in SJA/9 and nude mice. Surface IgE-positive cells were greatly increased in BALB/c and SJL/J mice after infection, but not in SJA/9 and nude mice. Most surface IgE-positive spleen cells were also surface IgM- and surface IgD-positive. When spleen cells from SJA/9 or nude mice were stimulated in vitro with lipopolysaccharide and recombinant interleukin 4 (formerly B cell-stimulating factor 1), IgE was produced and detected in the supernatants of these cultures. In addition, surface IgE-positive cells could be detected in these cultures. Most of the surface IgE-positive cells were surface IgM- and surface IgD-negative, unlike those seen in the spleens of Nippostrongylus-infected BALB/c and SJL/J mice. These observations show that SJA/9 and nude mice have IgE-producing precursor B cells, and after appropriate stimulation interleukin 4 can induce them to secrete IgE.     

Differences in the repertoire expressed by peritoneal and splenic Ly-1 (CD5)+ B cells.

Purified populations of B cells expressing the Ly-1 and/or Mac-1 surface Ag were isolated from normal unmanipulated mice by cell sorting. The number of lymphocytes in each population secreting antibodies reactive with DNA, bromelain-treated mouse RBC, phosphorylcholine and TNP-keyhole limpet hemocyanin was quantitated by ELISA spot assay. The proportion of B cells secreting Ig in vivo and the repertoire of antibodies they produced varied as a function of B cell phenotype and location. Among peritoneal lymphocytes, those that were Ly-1+ or Ly-1- Mac-1+ secreted Ig 10 times more frequently that Mac-1- Ly-1- B cells from the same location. In addition, the former populations expressed repertoires that were significantly skewed toward the production of antibodies reactive with bromelain-treated mouse RBC (p less than 0.001). In contrast, splenic B cells expressing the Ly-1 surface Ag did not differ significantly from splenic Ly-1- B cells in their expressed repertoire or frequency of Ig production. B cells isolated from the spleen and peritoneum tended to differ in antibody specificity from bone marrow and lymph node-derived lymphocytes. For example, B cells from the spleen secreted anti-DNA antibodies two to four times more frequently than B cells from other organs. These results demonstrate that phenotype and microenvironment influence the repertoire of antibodies expressed by B cells in vivo.     

Failure of (SJL/J x PL/J)F1 hybrid mice to develop immunologic tolerance to V beta 17a+ T cells results in F1 anti-SJL mixed lymphocyte reaction.

It has been reported previously that spleen cells from (SJL x PL) F1 hybrid mice are not tolerant to SJL parental cells as assessed by a one-way MLR. The possibility that the F1 anti-SJL reaction was due to the effect of lymphokines produced by the irradiated SJL T cells in response to I-Eu expressed on the F1 hybrid cells was eliminated since inclusion of anti-I-E mAb was without effect. Cell separations showed the responder cells to be plastic and nylon wool nonadherent Ia- T cells. Separation of the SJL spleen cells showed that the stimulator cells were nonadherent, passed through a nylon wool column, and were Ia-. the F1-anti-SJL MLR was blocked 70 to 90% by inclusion of mAb KJ23a in the culture medium that indicated that the stimulatory cell population was V beta 17a+ T cells. This was confirmed by the use of V beta 17a+ and V beta 17a-T cell clones as stimulators. To determine whether failure to develop tolerance to this T cell subset in F1 hybrid mice might be responsible for the F1-anti-parent MLR, (SJL x PL)F1 mice were treated at birth and 48 h thereafter with anti-I-E mAb for 7 wk. Spleen cells from antibody-treated F1 mice were nonreactive with irradiated SJL parental cells in contrast to spleen cells from control mice which indicated that V beta 17a+ T cells were eliminated by negative selection before the development of tolerance.