Functional heterogeneity among the T-derived lymphocytes of the mouse. III. Helper and suppressor T-cells activated by concanavalin A

An adjunct trait of HEL/I-Ab-specific T helper cell is sensitivity to antigen-specific immunosuppression

The present study tests whether the specific inhibition of helper T (Th) cell (and T hybridomas) by suppressor T (Ts) cells is a phenotypic trait of Th cells correlating with their acquired specificity for antigen/major histocompatibility complex or a genotypic trait not related to selection of the T cell repertoire for antigen. To do this we took advantage of the fact that H-2d parental strains of mice commonly restrict recognition of chicken egg-white lysozyme to the L3 peptide (a.a. 105-129) and H-2b parental mice to the L2 peptide (a.a. 13-105). F1 hybrids of these strains display two subsets of lysozyme-reactive T cells, one for each parental phenotype. Using (B10 X B10.D2)F1 mice reconstituted with B10.D2 bone marrow, we were able to develop genetic H-2d T cell clones that could express an atypical specificity, that is L2/I-Ab. Clones of this type, like genetic H-2b, are also sensitive to the inhibiting effects of HEL-activated Ts cells. To overcome some of the drawbacks of using heterogeneous populations of T, B and accessory cells in our assays, we constructed T hybridomas from HEL-immune, chimeric lymph node T cell blasts which respond to a unique antigen/major histocompatibility complex with production of the lymphokine interleukin 2. Our results indicate that all HEL/I-Ab-specific T cells (helper and hybridomas) are inhibited by suppression regardless of the T cell's haplotype at the H-2 locus: H-2b (B10), H-2d (D2) or H-2b,d (BDF1). Furthermore, there is a strict correlation between the antigen and I-A specificity: I-Ab-restricted T cells recognize non-L3 determinants even though some are derived from H-2d mice.

The antigen-specific, major histocompatibility complex-restricted receptor on T cells. VI. An antibody to a receptor allotype

We have prepared a monoclonal antibody, KJ16-133, from the cells of a rat immunized with the purified receptor for antigen plus I-A of a BALB/c T cell hybridoma, DO-11.10. Unlike most other monoclonal anti-receptor antibodies that have been described before, KJ16-133 is not clone specific. It reacts with approximately 20% of the receptors on T cells of normal BALB/c mice. It also reacts with about the same percentage of antigen-specific, major histocompatibility complex (MHC)-restricted or allogeneic I-region specific T cell hybridomas. Reaction of KJ16-133 with a given T cell hybridoma does not seem to depend on the antigen specificity or MHC-restricting element of the T cell in question. The determinant recognized by KJ16-133 has some unexpected properties. It is absent in several strains of mice including SJL/J and SJA/20, but present on the T cells of most other commonly used strains. The determinant recognized therefore does not map to Igh. Our experiments suggest that a clone-specific "antiidiotypic" antibody and KJ16-133 recognize determinants on different parts of the receptor. For example, the binding of a clone-specific antibody to target T cells is relatively temperature insensitive, whereas KJ16-133 binds well to cells at 37 degrees C but poorly to cells at 4 degrees C. The determinant recognized by a clone-specific antibody is sensitive to reduction and alkylation of the receptor, whereas KJ16-133 reactivity is not. Finally, binding of KJ16-133 at saturating concentrations to target T cells does not block the binding of a clone-specific antibody. Similarly, binding of a clone-specific antibody only marginally inhibits binding of KJ16-133. Taken together, these results suggest that KJ16-133 is directed against an allelic determinant on T cells that may be close to the membrane, and not in the receptor binding site for antigen plus MHC. The antibody may recognize an allele of a constant region isotype, or an allele of a J region.

Influenza viruses are T cell-independent B cell mitogens

UV-inactivated influenza virus A strains of subtypes H1, H2, H3, and H6 were shown to be mitogenic for unprimed splenic lymphocytes from BALB/c mice. Representative viruses of these four subtypes all behaved as T cell-independent B cell mitogens. The magnitude of the proliferative response was determined by the subtype of the hemagglutinin molecule: H2 and H6 viruses were the most potent mitogens, and H3 viruses were moderately mitogenic, whereas H1 viruses induced only low, but significant, levels of proliferation. Mitogenesis was inhibited by antiviral sera and by monoclonal antibodies directed against hemagglutinin.

The mouse T cell receptor: comparison of MHC-restricted receptors on two T cell hybridomas

The receptors for antigen plus a major histocompatibility complex (MHC) gene product on a T cell hybridoma specific for ovalbumin plus a Class II MHC product were compared with those on another T cell hybridoma, specific for a Class I MHC product. In each case receptor material was identified by a clone-specific monoclonal antibody. The two receptors proved to have very similar gross structures, being 70-85 kd proteins, and reducing to an acidic alpha-chain and a slightly basic beta-chain, each 40-43 kd. The charge of both the acidic and basic polypeptides varied between the two receptors studied, showing that variable amino acid sequences occur in both chains.

The major histocompatibility complex-restricted antigen receptor on T cells. I. Isolation with a monoclonal antibody

An antibody-secreting B cell hybridoma, KJ1-26.1, has been prepared from mice immunized with the T cell hybridoma DO-11.10, which recognizes chicken ovalbumin in association with I-Ad (cOVA/I-Ad). KJ1-26.1 blocks I-restricted antigen recognition by DO-11.10 and a subclone of this T cell hybridoma, DO-11.10.24, which has the same specificity for cOVA/I-Ad as its parent. KJ1-26.1 does not block I-restricted antigen recognition by any other T cell hybridoma tested, including a number of T cell hybridomas closely related to DO-11.10, with similar, but not identical, specificities for antigen/I. Moreover, KJ1-26.1 binds to DO-11.10 and DO-11.10.24, but not to any other T cell hybridomas tested, including three subclones of DO-11.10 that have lost the ability to recognize cOVA/I-Ad. Thus, in every regard KJ1-26.1 appears to be binding to all or part of the receptors for antigen/I on the T cell hybridoma DO-11.10. KJ1-26.1 appears to bind to approximately 15,000 molecules/cell on the surface of DO-11.10. The antibody precipitates an 80,000 dimer from the cells, which on reduction migrates as 40-44,000 monomers. The receptor(s) for antigen/I on DO-11.10 therefore includes molecules with these properties.

Characterization of a concanavalin A-induced amplifier T cell which augments in vitro antibody responses to DNP-Ficoll

The addition of the T-cell mitogen concanavalin A (Con A) on Day 2 of a 4-day in vitro culture of murine spleen cells with the thymus-independent (TI) antigen DNP39-Ficoll resulted in significant enhancement of the direct antitrinitrophenyl (TNP) plaque-forming cell (PFC) response. This enhancement was mediated by a nylon wool- and antiimmunoglobulin-nonadherent amplifier T cell (TA). TA activity was not eliminated by in vitro treatment of T cells with anti-Thy 1.2 and complement (C). TA activity could be eliminated by pretreatment of mice with antilymphocyte serum (ALS) in vivo, followed by in vitro treatment of T cells with anti-Thy 1.2 + C. Thus, TA appear to bear a low surface density of Thy-1 antigen. These TA were relatively resistant to ALS used alone, to cyclophosphamide, and to low dose in vitro irradiation. TA were still present in the spleen 14 weeks after adult thymectomy (ATx). They were I-J positive and apparently belonged to the Lyt 1+2- T-cell subset.

Antigen presentation by Ia+ B cell hybridomas to H-2-restricted T cell hybridomas

The Ia+, H-2d BALB/c lymphoma cell line L10.A 2J was fused to T cell-depleted spleen cells from mouse strains bearing other H-2 haplotypes. A portion of the selected hybrids expressed Ia antigens of the normal spleen cell partner in the fusion as evidenced by their presentation of various antigens to a set of antigen-specific I-region-restricted T cell hybridomas. Three cloned hybrids were studied in detail. Antigen presentation was shown to be inhibited specifically by monoclonal anti-Ia antibodies. Both I-A and I-E molecules were expressed, including in the one case examined hybrid I-A and I-E molecules between the H-2d and H-2b haplotypes. These Ia+ B cell hybridomas provide a useful set of tools for studying the role of I-region-encoded molecules in antigen presentation to T cells.

Positive selection of major histocompatibility complex-restricted suppressor T cells bearing the predominant idiotype in the immune response to lysozyme

The lysozyme system provides an excellent model for studying the role of multiple major histocompatibility complex (MHC) genes in the induction and regulation of Ir-gene controlled immune responses. Immunization of H-2b mice leads to concomitant activation of helper and suppressor activities by different epitopes on hen egg-white lysozyme (HEL) and thus phenotype unresponsiveness to native HEL. HEL-specific suppressor T cells in C57BL/10 nonresponder mice show MHC restriction, because their enrichment on antigen-pulsed macrophage monolayers requires syngeneic macrophages as well as HEL. The expression of the selected suppressor function requires interaction between the restricted suppressor precursor cell and an HEL-triggered, suppressor-inducer T cell. The MHC-restricted suppressor precursors bear the predominant idiotype found on anti-HEL antibodies, whereas MHC-restricted helpers do not.

Differential major histocompatibility complex-related activation of idiotypic suppressor T cells. Suppressor T cells cross-reactive to two distantly related lysozymes are not induced by one of them

B10 (H-2b) mice are genetic nonresponders to hen egg-white lysozyme (HEL) and the distantly related human lysozyme (HUL). However, anti-HEL or anti-HUL primary antibody responses in vivo or in vitro can be obtained in B10 mice by immunization with the appropriate lysozyme coupled to erythrocytes. T cells able to suppress either anti-lysozyme plaque-forming cells (PFC) response are induced in B10 mice after immunization with HEL-complete Freund's adjuvant (CFA) or HUL-CFA. This cross-reactivity of HEL and HUL in the induction and the expression of suppressive activity is in marked contrast to their very low cross-reactivity at the PFC level. These results suggest that either HEL or HUL can stimulate a suppressor T cell which recognizes a particular epitope present on both lysozymes. Suppressor cells induced by HEL or HUL bear the same predominant idiotype found on the majority of anti-HEL antibodies, and on the small proportion of anti-HUL antibodies cross-reactive with HEL. B10.Q (H-2q) mice are responders in vivo to HEL-CFA, but not to HUL-CFA. In contrast to B10, HEL-CFA priming in B10.Q micr induces helper cells whereas HUL-CFA priming induces suppressor cells. These suppressor cells are cross-reactive with HEL and are fully able to suppress HEL-specific helper cells. The presence of HEL-specific suppressor cell precursors in B10.Q mice which are not activated by HEL, seems to implicate differential choice by the antigen presenting system as a basis for Ir gene control, rather than the absence of a regulatory cell type from the T cell repertoire.

Reduction of trapping of aggregated human IgG in germinal centers by mitogens

The effect of nonspecific mitogens on the trapping of 125I-labeled aggregated human IgG (125I-AHGG) in germinal centers (GC) of mouse spleens has been investigated by both radioactivity uptake and immunofluorescence. Phytohemagglutinin and concanavalin A (Con A) significantly decreased trapping. Lipopolysaccharide produced less inhibition, and pokeweed mitogen had no significant effect. The maximum inhibition occurred with 250--500 mug Con A. This had no effect on 125I-AHGG uptake in liver kidney and blood. No differences were found between i.p. and i.v. routes of Con A injection. The effect of mitogens on the 125I-AHGG trapping in GC is due more likely to modification of the migratory properties of lymphocytes brought about by surface binding, than to their mitogenic properties, since Con A decreased 125I-AHGG localization in thymectomized, x-irradiated and bone marrow-reconstituted animals.