A non-T:non-B cell bears I-A, I-E, I-J, and Tla (Qa-1?) determinants

Cell-cell interaction responsible for the induction of first order suppressor T cells in hapten-specific contact sensitivity reactions

C3H/He mice were found to be low responders in the contact sensitivity response to ABA. Intravenous injection of ABA-coupled syngeneic spleen cells induced hapten-specific Ts in C3H/He mice. These cells were Ts1 because they acted on the inductive phase of the contact sensitivity. They could suppress the contact sensitivity in H-2-compatible CBA mice which were known to be high responders to ABA. Using in vivo and in vitro systems for the induction of Ts, it was shown that I-A-I-J+Thy-1- adherent cells were necessary as APC for the induction of Ts1.

I-J-positive cloned macrophages as accessory cells for the induction of suppressor T cells in vitro

I-A+/I-J+ cloned macrophages, SL-1, played the role of APC in the in vitro induction of Ts against DTH to BCG. By treating SL-1 cells with various antibodies, it was shown that I-J antigens on SL-1 cells are essential for Ts induction, but not for the effector cell induction for DTH. Ia-negative cloned macrophages, SL-4, did not show any APC activity either in suppressor or effector cell induction. The precursors of the Ts were also I-J-positive, and I-J restriction resided between T cells and macrophages in the Ts induction. Thus, it is suggested that the pre-Ts recognizes the antigenic determinants of BCG presented on the APC in association with the I-J antigen and differentiates into the Ts. This pathway seems analogous to that of helper or effector T induction, where the antigenic determinant is recognized by a T cell in association with the I-A antigen on APC.

I-J epitopes are adaptively acquired by T cells differentiated in the chimaeric condition

I-J has been defined as a locus mapped in the murine major histocompatibility complex (MHC) which encodes serological markers found primarily on the surface of suppressor T cells (TS) and soluble suppressor factors (TSF). Recent studies have, however, revealed that there is no such specialized locus within the MHC at the DNA level. As the existence of I-J determinants at the protein level on functional T cells, T-cell clones and hybridomas has been confirmed by several serological and biochemical studies, this contradiction has raised serious arguments in the immunological community concerning the nature, origin and expression of I-J determinants. We have raised a number of monoclonal antibodies against the polymorphic structure of I-J molecules, and have studied the expression of I-J epitopes on T cells derived from irradiated bone marrow chimaeras in which stem cells of different genotype differentiated into T cells under the foreign host MHC environment. The results, presented here, indicate that I-J epitopes are not primarily determined by the MHC genes of the stem cells themselves, but are adaptively acquired by T cells differentiated in the chimaeric condition according to the environmental MHC phenotype. Thus, the serologically detectable I-J epitopes are found to be associated with inducible T-cell receptors recognizing self class II MHC antigens.

Involvement of I-J epitopes in the self- and allo-recognition sites of T cells: blocking of syngeneic and allogeneic mixed lymphocyte reaction-responder cells by monoclonal anti-I-J antibodies

Monoclonal anti-I-Jk antibodies (mAbs) were found to inhibit syngeneic and allogeneic mixed lymphocyte reactions by blocking the responder T cells but not the stimulator cells. Only the responses of H-2k and H-2a strains were inhibited. Three different anti-I-Jk mAbs (1G8, 4B11, and KN34) showed different inhibitory patterns in allogeneic mixed lymphocyte reactions of individual H-2k strains, depending on the H-2 and immunoglobulin heavy chain variable region (IgVH) genes possessed by the stimulator strains. The results indicated that I-J epitopes are involved in the self- and allo-recognition sites of T cells, which are clonally distributed and used to recognize Ia plus IgVH-linked products.

Mechanisms of Ly2 suppressor cell activity. Activation of an Ly1 I-J+ cell is required to transduce the suppressive signal

A cell-free product secreted by Ly1-2+ T cells (Ly2 TsF) can suppress the in vitro response to sheep erythrocytes (SRBC) of spleen cells depleted of Ly2+ T cells. This suppressor factor expresses biological activity only when the acceptor cells share major histocompatibility complex (MHC)-linked polymorphic genes with the cells that made the Ly2 TsF. Removal of Ly1 I-J+ cells from the assay culture abrogates the ability of Ly2 TsF to suppress these cultures, but we can replace the need for the I-J+ cells in the assay culture with an I-J+ soluble factor derived from them. We investigated the cellular interactions involved in the activation of I-J+ cells by Ly2 TsF in vitro. We have been able to induce the production of an I-J+ molecule needed for Ly2 TsF activity in a 48-h intermediate culture of B cell-depleted Ly1 spleen cells, Ly2 TsF, and antigen. This molecule not only fails to bind antigen, but is also antigen nonspecific in that it can be induced by Ly2 TsF of irrelevant specificities. In order to replace the activity of the Ly1 I-J+ cell in the assay culture, the cell induced by Ly2 TsF to produce the I-J+ molecule in vitro must share genetic polymorphisms linked to the MHC with the Ly2 TsF, and genetic polymorphisms linked to the Igh-V gene complex with the target cell. In order for Ly2 TsF to induce cells of the primary culture to produce the I-J+ molecule, Ly2 TsF must share genetic polymorphisms linked to the IE region of the MHC with the Ly1 I-J+ cell producing the I-J+ molecule. These results indicate that the suppressive mechanism of Ly2 TsF involves the interaction with an Ly1 I-J+ molecule. This I-J+ molecule serves to focus the antigen-specific suppressor molecule on the target cell. The recognition event of this suppressive complex on the surface of the acceptor cell is controlled by Igh-V-linked genes restricted by the I-J+ molecule of the suppressor complex. This suppressor interaction is confined to the suppressor effector phase of the suppressor circuit since the I-J+ molecules needed for by Ly2 TsF activity do not substitute for the I-J+ molecules needed for the activity of Ly1 TsiF , a T cell factor that initiates the suppressor cell circuit.(ABSTRACT TRUNCATED AT 400 WORDS)

Idiotypic and fine specificity analysis of a (4-hydroxy-3-nitrophenyl)acetyl (NP)-specific suppressor T cell hybridoma at the level of cell surface structures, isolated receptor material and functional suppressor factor

The (4-hydroxy-3-nitrophenyl)acetyl (NP)-specific T suppressor cell hybridoma 7C3-13 was established by fusing splenic B10.BR T cells enriched on NP-coated petri dishes with the AKR thymoma BW5147. 7C3-13 was selected by anti-NPb idiotypic and anti-I-Jk antibodies in microcytotoxicity tests. The hybridoma expressed H-2k, I-Jk, Qa-1, Thy-1.1 as well as idiotypic (binding site-related) and framework Ig VH determinants, while it was negative for I-A, I-E/C, Thy-1.2, Lyt-1, Lyt-2 and Ig constant region determinants. Hapten-binding receptor material could be isolated from 7C3-13 cells on NP-coupled nylon nets and functionally active T suppressor factor (TsF) could be extracted from the hybridoma. Both types of soluble molecules express NPb idiotype, but the TsF carries I-J determinants in addition while the isolated receptors do not. The molecular weight of the isolated receptor material is 80 000, that of the TsF activity is 27 000 and 57 000-64 000, respectively. We thus were able to show that NP-binding molecules can be obtained in the form of cellular surface receptors, isolated receptor material and extracted TsF from one and the same, monoclonal, cell source.

In vitro induction of suppressor T-cells in delayed-type hypersensitivity to BCG and an essential role of I-J positive accessory cells

Antigen-specific suppressor T-cells in delayed-type hypersensitivity (DTH) to BCG were induced in vitro. Normal spleen cells of C3H/He mice were incubated with 50 micrograms of PPD per ml for 4 days at 37 degrees C, and the non-adherent cells in the culture were transferred intravenously into cyclophosphamide (CY)-treated syngeneic recipients. The recipients were immunized to BCG immediately after the cell transfer, and DTH was measured by the footpad reaction to PPD two weeks later. Footpad reaction to PPD was positive in CY-treated C3H/He mice immunized to BCG, while it was suppressed by the transfer of the in vitro induced suppressor cells. When the suppressor cells were treated with anti-thy-1.2 antiserum and complement before transfer, the suppression was abrogated. Next, the spleen cells were separated into plastic adherent and non-adherent fractions. After treatment with anti-thy-1.2 and complement, the adherent cells were treated with either anti-I-Jk or anti-I-Ak antiserum and complement. Then, they were reconstituted with the non-adherent cells and cultured with PPD. Treatment of the adherent cells with anti-I-Jk antiserum and complement abrogated the suppressor cell induction, while the treatment with anti-I-Ak had no effect. These facts indicate that I-J positive non-T-adherent cells play an essential role in the induction of suppressor cells in DTH.

The use of a monoclonal i-j-specific antibody to distinguish cells in the feedback suppression circuit from those in the contrasuppressor circuit

A monoclonal anti-I-Jb serum designated D-7 reacts in high titer with three different T-cell subsets and one cell-free product involved in generating contrasuppressive activity, but has no activity against I-J T-cell subsets (or their cell-free mediators) involved in feedback suppression. These results give evidence for heterogeneity in the I-J subregion. They also indicate that the serological markers on I-J+ cells may define the functional activity of the regulatory circuits they belong to. Clearly, they do not separate the role that the cells play within a particular immunoregulatory circuit, i.e., inducer, transducer, or effector cells.

Analysis of an antigen-specific H-2-restricted cell-free products(s) made by "I-J-" Ly-2 cells (Ly-2 TsF) that suppresses Ly-2 cell-depleted spleen cell activity

Immune Ly-1-,2+ splenic T cells release material(s) (Ly-2 TsF) into culture supernatants which (a) are antigen-specific and (b) do not contain gene products of the I-region of the MHC (major histocompatibility complex) (within the limits or our detection system) and which can lead to antigen-specific suppression of spleen cell cultures depleted of all Ly-2+ (Ly-2 and Ly-1,2) cells. The cells which make Ly-2 TsF possess no detectable I region- or Qa-1-encoded determinants. Nonetheless, the ability of the material(s) to suppress target cells is restricted by genes closely linked to the MHC. No demonstrable evidence for a role of the polymorphic portion of genes linked to the Ig locus for this suppressive interaction to occur could be found. It is suggested that this material(s) may be the final effector moiety of the suppressor circuit because (a) it does not require the presence of any Ly-2+ cells to work, and (b) in contrast to material(s) which induce suppression, there is no latent period; i.e. the Ly-2 TsF suppresses both the early and late phases of the immune response in primary Mishell-Dutton cultures. The MHC restriction that is imparted to the biologically active material is likely to be due to its "anti-MHC" activity. Since this is the first report in which the presence of I-J-controlled gene products was investigated on an antigen-specific, Ly-2 cell-produced suppressor factor that worked in the absence of Ly-2+ cells in the assay culture, the possibility that many, if not all, antigen-specific suppressor effector cells and molecules are "I-J-" must be considered.

In vivo effects of antibodies to immune response gene products: prevention of experimental allergic encephalitis

Prevention of experimental allergic encephalitis in SJL/J [H-2s] mice was achieved with in vivo administration of antibody reactive with I-As gene products prior to immunization with spinal cord antigen. No protection was evident in animals that received antisera specific for I-Js gene products. Administration of antibody to I-As beginning 5 days after immunization with spinal cord antigen delayed, but did not prevent, the onset of experimental allergic encephalitis.

T cells in a suppressor circuit and non-T:non-B cells bear different I-J determinants

T cells involved in the generation of suppressor activity bear an I-J-subregion controlled determinant (e.g., J1) which is distinct from that (e.g., J2) found on non-T:non-B accessory cells. T-cell subsets examined include Ly-1 inducer and Ly-1,2 acceptor cells which collaborate to generate suppressor activity in the in vitro sheep red blood cell antibody system. Non-T:non-B accessory cells examined include accessory cells involved in concanavalin-A induced, T-cell proliferative responses and in in vitro antibody responses to sheep red blood cells. These results provide evidence for serologic and genetic complexity of the I-J subregion of the murine H-2 gene complex.