Murine T-cell clones specific for chicken erythrocyte alloantigens

In vivo generated Th1 cells can migrate to B cell follicles to support B cell responses

The description of Th1 and Th2 T cell subsets rationalized the inverse correlation between humoral and cell-mediated immunity. Although Th1 cells were described to support cell-mediated immune responses, their role in supporting certain B cell responses was firmly established. However, there is now a prevailing preconception that provision of B cell help is entirely the domain of Th2 cells and that Th1 cells lack this capacity. Previous studies demonstrated that immunization using aluminum hydroxide adjuvants induces Ag-specific Th2 responses, whereas incorporation of IL-12 with aluminum hydroxide produces a Th1 inducing adjuvant. By immunizing TCR transgenic recipient mice in this fashion, we have generated Ag-specific, traceable Th1 and Th2 cells in vivo and assessed their follicular migration and ability to support B cell responses. In this study we have shown that in vivo polarized Th1 and Th2 cells clonally expand to similar levels and migrate into B cell follicles in which they support B cell responses to a similar degree. Critically, we present direct evidence that in vivo polarized, IFN-gamma secreting Th1 cells migrate into B cell follicles where they can interact with Ag-specific B cells.

Immunological response in mice after long-term stimulation with cell wall antigens from Brucella melitensis

The continuous stimulation of the immune system using cell wall antigens from Brucella melitensis was found to cause both quantitative and qualitative changes in circulating lymphocyte populations in mice. Animals were inoculated in the hind legs with antigens on alternate days for varying lengths of time. During a two-month period, we saw a higher number of circulating lymphocytes, with an increase in the number of CD4+ cells (L3T4+) and B lymphocytes (I-Ad). After two months, a drop in the overall number of circulating lymphocytes occurred, with a decrease in CD4+ cells and an increase in CD8+ cells. During the first two months, we observed a size increase in popliteal lymph nodes and an elevated humoral response. The response then waned with the declining CD4+ cells. In the first two months, the treated animals also showed an in vitro response to two mitogens, concanavalin A and lipopolysaccharide and to the cell wall fraction, after which the treated animals showed a decreased response.

Regulation of the interaction between Th1 and Th2 T cell clones to provide help for antibody production in vivo

On the premise that an individual with an intact immune system has the capability to develop both cellular and antibody immune responses supported by the balance between the lymphokines secreted by T helper (Th) cells, we studied the interaction between different types of Th cell clones in vivo and the parameters that may affect this interaction. We used an adoptive transfer system in which nude or lethally irradiated mice were reconstituted with histocompatible CD4+ keyhole limpet hemocyanin (KLH)-specific T cell clones with defined lymphokine profiles. This approach allowed us to study the effects of the cognate interaction between T and B cells in the presence of a defined set of lymphokines. We demonstrated that the co-transfer of both subsets of Th cells resulted in increased production of IgA, and decreased production of IgE and IgG2a. The concomitant presence of both cell types also increases their functional survival in vivo. We have shown that in the presence of a Th2 clone, higher immunization doses (above 100 micrograms trinitrophenol (TNP)-KLH/mouse) result in increased production of IgE and IgG1. In contrast, when a Th1 clone is present, low immunization doses (less than 50 micrograms TNP-KLH/mouse) resulted in increased production of IgG2a. We were also able to show that the neutralization of interleukin-4(IL-4) and or interferon-gamma (IFN-gamma) was sufficient to abrogate most of the regulatory effects caused by the Th2 or the Th1 clone respectively. Our results indicate that the subset of T cell(s) transferred determines the type of response obtained. In addition, the data presented indicate that the antigen dose used for immunization can modulate the quantitative parameters of the response. Furthermore, we have shown that the interaction between the two subsets of T cells in vivo is characterized by both antagonistic and agonistic effects and that most of the regulatory effects exerted by one subset over the other are mediated by IL-4 or IFN-gamma.

Heterogeneity of helper T cell subsets in Peyer's patches

The OX22 monoclonal antibody recognizes the high molecular weight form of the CD45 molecule on rat T cells encoded by the CD45RC exon of the leukocyte common antigen gene. Its expression on CD4+ T cells is associated with virgin unprimed cells and primed cells which produce IL-2 and IFN-gamma on stimulation and participate in cell-mediated immune reactions. This suggested that CD45RC expression may be useful as a phenotypic marker for cells expressing Th1 function. In view of our previous data indicating heterogeneity of T-cell helper function in different lymphoid compartments in the gut, the helper activity of OX22-enriched or OX22-depleted cell populations prepared from Peyer's patches (PP) of rats was compared. Following intestinal immunization with keyhole limpet haemocyanin, PP cells were isolated and separated by panning. Recovery data indicated that the majority of T cells in rat PP express the OX22+ phenotype and, after separation, the OX22-enriched population contained 4 times as many cells as the OX22-depleted population. Functional studies revealed that both subsets were capable of providing cognate help for secondary IgM, IgG and IgA antibody responses indicating that on this basis the CD45RC marker does not correlate with Th1 function in rats.

Effects of tolerance induction on early cell cycle progression by Th1 clones

Human gamma-globulin (HGG)-specific mouse Th1 clones exposed to tolerogenic signals provided by HGG-pulsed paraformaldehyde-fixed splenocytes (HGG-FAPC) were analyzed for antigen-induced progression through the early phases of the cell cycle. Exposure of Th1 clones to HGG-FAPC in primary cultures inhibits the ability of the clones to synthesize DNA in response to HGG and normal APC in secondary cultures. The Th1 clones in these secondary cultures were found to be blocked in G1a phase as evidenced by cell cycle analysis and by reduced numbers of cells expressing high levels of IL-2R and TfR. This cell cycle blockade of Th1 cells was not observed if the secondary cultures were stimulated with IL-2-containing Con A CM instead of antigen. These data suggest that in our system the inhibition in antigen-induced cell cycle progression associated with Th1 tolerance induction occurs at the G1a/G1b phase transition.

Helper activity for immunoglobulin synthesis of T helper type 1 (Th1) and Th2 human T cell clones: the help of Th1 clones is limited by their cytolytic capacity

A large number of CD4+ human T helper type 1 (Th1) clones specific for purified protein derivative and of Th2 clones specific for the excretory/secretory antigen of Toxocara canis, derived from the same individuals, were analyzed for both cytotoxic capacity and helper function for immunoglobulin (Ig) synthesis. The great majority of Th1, but only a minority of Th2 clones exhibited cytolytic activity. All Th2 (noncytolytic) clones induced IgM, IgG, IgA, and IgE synthesis by autologous B cells in the presence of the specific antigen, and the degree of response was proportional to the number of Th2 cells added to B cells. Under the same experimental conditions, Th1 (cytolytic) clones provided helper function for IgM, IgG, and IgA, but not IgE, synthesis with a peak response at 1:1 T/B cell ratio. At higher T/B cell ratios, a strong decrease of Ig synthesis was observed. All Th1 clones lysed Epstein-Barr virus transformed autologous B cells pulsed with the specific antigen. The decrease of Ig production at high T/B cell ratios correlated with the lytic activity of Th1 clones against autologous antigen-presenting B cell targets. These data suggest that Th1 differ from Th2 human T cell clones not only for their profile of cytokine secretion, but also for cytolytic potential and mode of help for B cell Ig synthesis.

Role of iron in T cell activation: TH1 clones differ from TH2 clones in their sensitivity to inhibition of DNA synthesis caused by IgG Mabs against the transferrin receptor and the iron chelator deferoxamine

TH1 and TH2 helper T cell clones have been studied with respect to their sensitivity to inhibition of DNA synthesis by an IgG anti-transferrin receptor antibody (ATRA), the iron chelator deferoxamine, and the combination of the two reagents. TH1 clones are very sensitive to ATRA-mediated inhibition of DNA synthesis while TH2 clones are very resistant, but both TH1 and TH2 clones show significant down-modulation of surface transferrin receptors after ATRA exposure. TH2 clones exhibit larger chelatable iron storage pools than TH1 clones, however, and even partial chelation of TH2 cell storage iron does not fully convert a TH2 clone to the ATRA sensitivity pattern of a TH1 clone. It is therefore proposed that the greater resistance of TH2 clones to ATRA mediated inhibition derives from the combined effects of larger and less labile iron storage pools. These studies provide novel evidence indicating that nonuniform iron metabolism can exist within the T cell compartment and thus raise questions as to why such differences exist and how they can be integrated into models of the T cell activation process. These studies also suggest that the cell-mediated immune response in vivo, which is known to be sensitive to iron deficiency, may be evoked by effector cells which resemble TH1 clones insofar as iron metabolism is concerned.

Expression of CD4 can confer major histocompatibility complex class II-associated superantigen reactivity upon a T cell receptor derived from a CD8-dependent cytotoxic T lymphocyte clone

It has been shown that reactivity against major histocompatibility complex (MHC) class II-associated Mlsa determinants is mainly mediated by CD4+ V beta 6+ T cells. 3F9 is a CD8+ CTL clone which is specific for the alloantigen H-2Db. While 3F9 is V beta 6+, it is not Mlsa reactive, presumably because it does not express CD4. 3F9 utilizes the same T cell receptor (TcR) V alpha V beta combination as LB2, a CD4+ T helper clone specific for chicken red blood cells (cRBC)/I-Ab and yet differs from LB2 in the junctional sequences in both TcR chains. CD4+ CD8- and CD4-CD8- hybridomas expressing the 3F9 TcR were tested for reactivity against Mlsa and cRBC/I-Ab. Only the CD4+CD8- hybridomas were Mlsa reactive, and antibody inhibition studies revealed that this reactivity was both CD4 and MHC class II dependent. Therefore the expression of the CD4 molecule can make an MHC class I-restricted TcR Mlsa reactive. Neither type of hybridoma reacted against cRBC, thus the main difference in the antigen reactivity between 3F9 and LB2 lies in the TcR junctional regions.

Induction of antibody synthesis by CD4+ T cells: IL 5 is essential for induction of antigen-specific antibody responses by TH2 but not TH1 clones

Murine B cells stimulated with lipopolysaccharide (LPS) and interleukin (IL) 4 produce IgG1 and IgE, but synthesize IgG2a when stimulated with LPS and interferon-gamma. The cytokines, however, that regulate immunoglobulin (Ig) synthesis induced in normal B cells under antigen-driven major histocompatibility complex (MHC)-restricted conditions in the absence of potent B cell mitogens have not been fully elucidated. We and others have shown that under cognate MHC-restricted conditions, CD4+ T cell clones of the TH1 subset, which produce IL 2 and interferon-gamma, and T cell clones of the TH2 subset, which produce IL 4 and IL 5, are both capable of inducing anti-trinitrophenyl IgG plaque-forming cells. In this report we have examined in further detail the cytokine requirements for the induction of Ig synthesis in B cells cultured directly with TH1 and TH2 T cell clones. Using (a) TH2 clones that varied in the amount of IL 5 secreted, (b) a neutralizing monoclonal antibody against IL 5 and (c) T cell clones pretreated with cyclosporin A to inhibit cytokine secretion, we found that IL 5 was essential for induction of IgG1 synthesis by TH2 but not TH1 T cells. Although we demonstrated that IL 2 could actually up-regulate the synthesis of IL 5 by TH2 clones, the induction of IgG synthesis by TH2 clones was entirely independent of IL 2. In contrast, induction of IgG1 synthesis by TH1 clones was absolutely dependent upon the presence of IL 2 and was not affected by the presence of IL 5. Thus, these studies demonstrate the idea that at least two independent pathways exist for the induction of IgG1 synthesis, and that one of these pathways is IL 4/IL 5 dependent and the other IL 2 dependent.

Two types of mouse T helper cell. IV. Th2 clones secrete a factor that inhibits cytokine production by Th1 clones

A cytokine synthesis inhibitory factor (CSIF) is secreted by Th2 clones in response to Con A or antigen stimulation, but is absent in supernatants from Con A-induced Th1 clones. CSIF can inhibit the production of IL-2, IL-3, lymphotoxin (LT)/TNF, IFN-gamma, and granulocyte-macrophage CSF (GM-CSF) by Th1 cells responding to antigen and APC, but Th2 cytokine synthesis is not significantly affected. Transforming growth factor beta (TGF-beta) also inhibits IFN-gamma production, although less effectively than CSIF, whereas IL-2 and IL-4 partially antagonize the activity of CSIF. CSIF inhibition of cytokine synthesis is not complete, since early cytokine synthesis (before 8 h) is not significantly affected, whereas later synthesis is strongly inhibited. In the presence of CSIF, IFN-gamma mRNA levels are reduced slightly at 8, and strongly at 12 h after stimulation. Inhibition of cytokine expression by CSIF is not due to a general reduction in Th1 cell viability, since actin mRNA levels were not reduced, and proliferation of antigen-stimulated cells in response to IL-2, was unaffected. Biochemical characterization, mAbs, and recombinant or purified cytokines showed that CSIF is distinct from IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IFN-gamma, GM-CSF, TGF-beta, TNF, LT, and P40. The potential role of CSIF in crossregulation of Th1 and Th2 responses is discussed.

Collaboration of Th1 and Th2 T cell clones in specific antibody responses: regulation of the IgM response to phosphorylcholine

Carrier (KLH)-specific type 1 T cell clones (Th1), which are defined by secretion of IL-2 and IFN-gamma but not IL-4, and type 2 (Th2) clones, which secrete IL-4, but not IL-2 or IFN-gamma, have been isolated and analyzed for their ability to collaborate in providing help for B cells to secrete phosphorylcholine-specific IgM antibodies. The resulting antibody responses exhibited a characteristic pattern suggesting two distinct regulatory interactions among the Th1, Th2, and B cells. At low doses of antigen, Th1 cells enhanced the helper function of the Th2 cells, an effect due primarily to IL-2. At high doses of antigen, Th1 cells or IFN-gamma inhibited Th2-dependent antibody responses. The inhibitory effect of Th1 or IFN-gamma affected primarily the hapten-carrier-linked portion of the response. The overall effect was a modulation of the antigen dose-response curve for antibody production, eliminating the sharp increases in dose response mediated by isolated T cell clones. The data suggest that collaborative interactions of Th1 and Th2 cells in antibody production may have important physiological consequences.

Murine CD4+ T cell subsets defined

We have used two monoclonal anti-murine T cell autoantibodies (SM3G11 and SM6C10) and multi-color immunofluorescence staining to resolve splenic CD4+ cells into four populations. Two of these populations (Fr. I and Fr. III, 35% and 10% of CD4+ cells) show mutually exclusive expression of these determinants and exhibit distinct functions. Fr. III secretes IL-4, but not IL-2 when activated by Con A, and includes memory T cells responsible for secondary antibody formation. In contrast, Fr. I secretes IL-2 but not IL-4 in response to Con A, and does not contribute to the secondary antibody response. Furthermore, these two fractions exhibit differential accessory cell dependence. Whereas Fr. III responds with B cells (and also non-B cells) as accessory cells in Con A-induced activation, Fr. I requires non-B cells. However, we found that many CD4+ cells (Fr. II, 40% of CD4+ cells) express both determinants and are not distinguishable with regard to lymphokine secretion, accessory cell effect, and memory T cell activity. Curiously, the fraction expressing neither determinant (Fr. IV, 10% of CD4+ cells) is unresponsive to experimental conditions used here. We discuss the possible relationships between these T cell subsets and the implications of differential expression of these determinants.

Two monoclonal rat antibodies with specificity for the beta-chain variable region V beta 6 of the murine T-cell receptor

Two rat monoclonal antibodies (mAbs), 44-22-1 and 46-6B5, which recognize an alloreactive cytotoxic clone, 3F9, have been further tested on a panel of T hybridomas and cytotoxic T-cell clones for binding and functional activities. The mAbs recognized only those cells sharing the expression of the T-cell receptor beta-chain variable region gene V beta 6 with 3F9. All V beta 6+ cells were activated by these mAbs under cross-linking conditions and their antigen-specific activation was blocked by soluble mAb. Furthermore, depletion of 46-6B5+ normal lymph node T cells eliminated all cells expressing the epitope recognized by 44-22-1 and V beta 6 mRNA.

Heterogeneity of helper/inducer T lymphocytes. II. Effects of interleukin 4- and interleukin 2-producing T cell clones on resting B lymphocytes

To compare the helper function of murine T cell clones that secrete IL-2 and IFN-gamma (Th1 cells) or IL-4 and IL-5 (Th2), purified resting B cells were stimulated with F(ab')2 rabbit anti-mouse Ig (RAMG) and rabbit Ig-specific, class II MHC-restricted cloned T cells belonging to the two subsets. Both Th2 clones examined induced strong proliferative responses of B cells in the presence of RAMG, as well as the secretion of IgM and IgG1 antibodies. In contrast, the Th1 clones tested failed to stimulate B cell growth or antibody secretion. Th2-mediated B cell activation was dependent on IL-4 and IL-5, and was also inhibited by IFN-gamma or IFN-gamma produced by Th1 cells present in the same cultures. However, the failure of Th1 cells to help resting B cells could not be reversed with neutralizing anti-IFN-gamma antibody. In addition to this inhibitory effect, IFN-gamma was required for the secretion of IgG2a antibody, particularly when B cells were stimulated with polyclonal activators such as LPS. Finally, both sets of T cell clones secreted lymphokines when stimulated with purified B cells and RAMG. These experiments demonstrate that T cells that differ in lymphokine production also differ in their ability to help B cells as a result of cognate interactions at low concentrations of antigens. Moreover, IL-4, IL-5, and IFN-gamma serve different roles in the T cell-dependent proliferative and differentiative responses of resting B lymphocytes.

Enhanced response of autoantibody-secreting B cells from young NZB/NZW mice to T-cell-derived differentiation signals

Spleen cells from young NZB/NZW mice spontaneously produce IgM antihistone and anti-DNA antibodies in culture, and this in vitro autoantibody production is T-cell dependent. In the present studies, we investigated the response of young autoantibody-producing NZB/NZW B cells to various T-cell-derived signals. Stimulation with unprimed allogeneic T cells resulted in a 10- to 20-fold increase in IgM antihistone and anti-DNA antibody production compared with cultures of B cells alone. The responding cells were found in the large B-cell fraction after separation on Percoll gradients. Allo-stimulated B cells from nonautoimmune mice produced much lower absolute amounts of IgM autoantibodies as well as total IgM compared with NZB/NZW cells. Marked IgM antinuclear antibody and total IgM production was also observed when NZB/NZW B cells were cultured with supernatants from TH2 but not TH1 T-helper clones. Although B cells from nonautoimmune mice produced high levels of autoantibodies after stimulation with lipopolysaccharide, only minimal levels were secreted in response to the active supernatants. These results suggest that young NZB/NZW mice have IgM autoantibody-producing B cells that are more sensitive to certain T-cell-derived signals compared with B cells from normal mice. Although these hyperresponsive NZB/NZW cells appear to be in an advanced stage of activation, they require additional T-cell signals to express this abnormality.

Two types of mouse helper T cell clone. III. Further differences in lymphokine synthesis between Th1 and Th2 clones revealed by RNA hybridization, functionally monospecific bioassays, and monoclonal antibodies

Lymphokine synthesis patterns of a panel of 19 T cell clones have been evaluated, using mRNA hybridization methods to examine 11 different mRNAs induced by Con A. The two types of CD4+ Th cell clone described previously were clearly distinguished by this procedure, and the differences between the two types have now been extended to six induced products. With minor exceptions, only Th1 clones synthesized mRNA for IL-2, IFN-gamma, and lymphotoxin, and only Th2 clones synthesized mRNA for IL-4, IL-5, and another induced gene, P600. Four more induced products were expressed preferentially but not uniquely by one or another type of clone: mRNAs for GM-CSF, TNF, and another induced, secreted product (TY5) were produced in larger amounts by Th1 clones, whereas preproenkephalin was preferentially expressed by Th2 clones. IL-3 was produced in similar amounts by both types of clone. mAbs were used to establish three bioassays that were functionally monospecific for IL-2, IL-3, and IL-4, and a new anti-IFN gamma mAb, XMG1.2, was used to establish an ELISA for IFN-gamma. These four assays were used to show that secreted protein and mRNA levels correlated well for all cell lines. The implications of these findings for normal T cells are discussed.

Fine specificity and T-cell receptor beta-chain gene rearrangements of five H-2Db-specific cytotoxic T-cell clones

A panel of cytotoxic T lymphocyte clones that recognize H-2b target cells has been established. Six different clones were distinguished according to the following criteria. First, the fine specificity of the clones was determined by testing proliferation and cytotoxicity on target cells of recombinant mice. Clone 221 recognized H-2Kb, and five other clones recognized H-2Db. Clone 433 distinguished itself from the other five Db-specific clones by cross-reacting with an antigen on H-2k cells. Second, the presence of an idiotypic determinant as defined by the 3F9 clone-specific monoclonal antibodies was investigated in cytotoxicity inhibition experiments. One of the Db-specific clones, 653, was inhibited by these antibodies and was therefore clearly different from the other Db-specific clones. The third criterion involved the rearrangement pattern of the DNA coding for the beta chain of the T-cell receptor. Southern blot analysis showed that each clone had a unique pattern. Interestingly, clone 653, which expresses the same idiotypic determinant as clone 3F9, had deleted the C beta 1 gene cluster, whereas this gene is functionally expressed in clone 3F9.

T-cell antigen receptors with identical variable regions but different diversity and joining region gene segments have distinct specificities but cross-reactive idiotypes

The T-cell antigen receptor alpha-chain genes of an alloreactive, H-2Db-specific cytotoxic T-cell clone (3F9) are described. This study and our work on the 3F9 beta-chain genes reveal that the variable region gene segments for the alpha and beta chains expressed in 3F9 are identical to the ones used by a chicken erythrocyte-specific, I-Ab-restricted helper T-cell clone (LB2). These two clones differ, however, in the diversity and joining portions of the alpha and beta chains of their T-cell receptor molecules. The analysis of 3F9 and LB2 with monoclonal antibodies specific for the 3F9 T-cell receptor shows that these two T-cell clones share the same idiotype; however, 3F9 and LB2 do not exhibit any antigen and/or major histocompatibility complex cross-reactivity. This suggests that the diversity and joining regions of the T-cell receptor may play a key role in antigen and/or major histocompatibility complex recognition.

T-cell and mast cell lines respond to B-cell stimulatory factor 1

The murine lymphokine B-cell stimulatory factor 1 (BSF-1) has been described previously in terms of its action on B lymphocytes. We now provide evidence that BSF-1 is also responsible for two additional biological activities. The first of these is the stimulation or maintenance of a state of activation in mouse T-cell lines. The second activity is the increase in the proliferative rate of certain mast cell lines costimulated with interleukin 3. The T-cell and mast cell activities are mediated by purified BSF-1 and copurify with BSF-1 from supernatants of certain T-cell lines. Each of these activities is inhibited by monoclonal anti-BSF-1 but not by monoclonal anti-interleukin 2 antibody. The antibody inhibition results also indicate that BSF-1 is the major or only source of these two activities in the activated T-cell supernatants that we have tested.