The role of antigen-specific T cell factors in the immune response

Mouse T-lymphocyte subpopulations: relationships between function and Lyt antigen phenotype

The study of cell-surface markers has permitted the dissection of lymphocyte populations into subsets and made possible many of the current ideas about how cells interact to produce an immune response. In particular, the Lyt molecules of the mouse, originally described by Boyse and his colleagues, have been of great importance in defining functionally distinct subsets of T cells and examining the interactions among them (reviewed in Ref. 2). A major question raised by these studies concerns the nature of the relationship between Lyt phenotype and the function of the T-cell subset so defined. Are such associations fortuitous, are they indirect manifestations of some other factor(s), or do they indicate that the molecules themselves have a functional role? In this article, Susan Swain and Richard Dutton discuss what is known about Lyt antigens, how their expression correlates with function of T cells and with the recognition of major histocompatibility complex (MHC) subregion antigens by T cells, and what role(s) such molecules may have in T-cell activities.

The beneficial effect of donor-specific transfusions: a review of existing explanations and a new hypothesis based on a relatively unapplied theory of T cell immunoregulation. A regulatory hypothesis in progress

The mechanism by which donor specific transfusions protect a graft from the recipient's immune system is unknown. It is likely that this beneficial mechanism is a subset or distinct exhibition of the general rules governing the regulation of the immune system. This phenomenon provides a strong framework for investigation of immune regulation, considering its potential consanguinity to immune regulation, that it is a paradox representing a manifestation of regulatory rules, and that it provides a wealth of clinical experience and experimentation from which to make inferences. Vital in any exploration of immune regulation, is the promise held in reducing the immune system to its chief elemental regulatory mechanisms and interactions. Strangely, the majority of this consequential work may have already been accomplished by Gershon, Green and colleagues with their elegant demarcation of T cell regulation into suppressor and contrasuppressor pathways. The practical and theoretical implications of this discovery seem to be, for the most part, ignored by mainstream immunology. It is doubtful, based on the quality and quantity of their work, or confirming work by other laboratories that they were inaccurate in their findings. It remains a horrible waste that their discoveries are not in immunology's pantheon of hallowed discoveries and are little used. With all this kept in mind, a comprehensive hypothesis of regulation was put together based mainly on Gershon's portrait of the suppressor and contrasuppressor pathways' contributions to immune regulation and experimentation surrounding the unsolved paradox of donor specific transfusions.

IBDV-induced bursal T lymphocytes inhibit mitogenic response of normal splenocytes

We examined the suppressive activity of bursal T cells induced by infectious bursal disease virus (IBDV) in inbred (15x7) and outbred commercial specific-pathogen-free (SPF) chickens. The suppressive activity was measured by the ability of bursal and splenic T cells from IBDV-infected chickens to inhibit mitogenic responses of normal splenocytes. The bursacytes but not the splenocytes of IBDV-infected chickens inhibited the mitogenic responses of normal splenocytes. The mitogenic inhibition by the bursacytes of IBDV-infected chickens was dose-dependent. The suppression was observed both in inbred and non-inbred chickens, and thus, was non MHC-restricted. Cell-sorting experiments revealed that both CD4(+) and CD8(+) cells from the bursa of IBDV-infected chickens, as well as cell-culture supernatants conditioned by these cells, mediated suppression. Suppressor T (Ts) cells may therefore be involved in the immunosuppression induced by IBDV.

T cell mediated immunosuppression

Suppressor T cells down-regulate the activity of other cells in the immune system, and, albeit controversial, are believed to play a role in immunological tolerance and immunoregulation. Significant progress has been made in characterizing suppressor T cells and their receptors, and in elucidating mechanisms of immunosuppression. This knowledge is important for understanding the immune system and certain disease states and for favorably manipulating immunity.

Localization of the virus neutralizing and hemagglutinin epitopes of E1 glycoprotein of rubella virus

Current serological assays using whole rubella virus (RV) as a target antigen for detecting RV-specific antibodies fail to define specific RV proteins and antigenic determinants such as hemagglutinin (HA) and virus-neutralizing (VN) epitopes of rubella virus. A panel of E1 deletion mutants and a subset of E1-specific monoclonal antibodies (MAb) were used for the initial analysis of HA and VN epitopes of E1 glycoprotein. A peptide region (E1(193) to E1(269)) was found to contain HA and VN epitopes. Using both overlapping synthetic peptides and truncated fusion proteins within this region, the HA epitope defined by MAb 3D9F mapped to amino acid residues E1(214) to E1(240), while two VN epitopes defined by MAb 21B9H and MAb 16A10E mapped to amino acid residues E1(214) to E1(233) and E1(219) to E1(233), respectively. The epitopes defined in this study are recognized by antibody whether or not the epitopes are glycosylated.

Establishment of stable CD8+ suppressor T cell clones and the analysis of their suppressive function

Stable CD8+ suppressor T cell (Ts) clones were established by a relatively simple method. Keyhole limpet hemocyanin (KLH)-primed spleen cells from C3H mice were depleted of B cells and CD4+ T cells by panning and cytotoxic treatment, and the resulting CD8+ T cells were periodically stimulated with antigen and irradiated syngeneic spleen cells followed by manifestation in interleukin-2 (IL-2) containing medium. T cell clones with a definite suppressor function were established by limiting dilution. They were defined as classical effector type Ts of CD8+ phenotype as they had constant and definite suppressor functions in antigen-induced T cell proliferation and specific antibody response against T cell-dependent antigens without detectable cytotoxic activity against both antigen presenting cells (APC) and helper T cells (Th). They showed no helper activity for B cells and produced no detectable helper type lymphokines such as IL-2 and IL-4. CD8+ Ts clones were able to inhibit the antigen-induced IL-2 production of normal and cloned T cells. Their suppressive activity was antigen-nonspecific and major histocompatibility complex-unrestricted. CD8+ Ts clones were also able to suppress the proliferative response of Th clones induced by immobilized anti-T cell receptor (TcR) and anti-CD3 mAbs but not the response induced by concanavalin A (ConA) and IL-2. All the CD8+ T cell clones established independently utilized the TcR V beta 8 gene. Syngeneic antigen presenting cells could induce proliferation of these CD8+ clones, which was blocked by anti-CD8 and anti-I-Ak monoclonal antibody (mAb) but not by anti-class I mAbs. The stimulation of CD8+ Ts clones with immobilized anti-CD3 resulted in the release of a suppressor factor(s) that potently inhibited the antigen-induced proliferation of CD4+ Th clones and the in vitro secondary antibody formation.

Modulation of the secondary antibody response of murine lymphocytes to sheep red blood cells in vitro by neuraminidase and exoglycosidases

The effect of digestion of lymphocytes with neuraminidase and exoglycosidases on the secondary antibody response in vitro to sheep red blood cell (SRBC) antigen was tested. Treatment of spleen cells from SRBC-primed mice with 3 micrograms/ml of neuraminidase slightly but significantly augmented their plaque-forming cell response to SRBC, whereas treatment with 100 micrograms/ml of a mixture of exoglycosidases did not. Rather unexpectedly, however, treatment of the spleen cells with the mixture of both neuraminidase and exoglycosidases greatly augmented the response. This enzyme action was substrate specific inasmuch it was ablated by addition of mucin as a neuraminidase inhibitor to the enzyme mixture. The target of the enzyme activity was not glass-adherent macrophages, but was glass-non-adherent suppressor cells in the antigen-primed cell population. Evidence was provided that the phenotype of suppressor cells whose activity was ablated by the enzyme treatment was Thy-1+. It is suggested from these results that sialylated complex type oligosaccharides on antigen-primed T cells play a critical role in their suppressor activity.

Characterization of antigen-specific suppressor factors induced by staphylococcal enterotoxin B

Previous studies from this laboratory have shown that staphylococcal enterotoxin B (SEB) has the capacity to nonspecifically induce multiple T suppressor cell populations which are capable of regulating both primary and secondary in vitro antibody responses. Additional studies have revealed that the suppressive activity of these cells is mediated, at least in part, by an I-J-restricted suppressor-inducer factor. Efforts to characterize the specificity of this inducer molecule have demonstrated the presence of multiple antigen-specific suppressor factors within SEB-stimulated supernatants. Antigen-binding molecules present within these SEB-induced factor preparations were isolated and concentrated over antigen-coupled columns. The results have demonstrated that eluates from trinitrophenyl-ovalbumin and trinitrophenyl-keyhole limpet hemocyanin-coupled columns significantly suppress both primary and secondary anti-TNP plaque-forming colony responses, whereas the filtrates from these columns demonstrated little to no inhibitory activity. The filtrates, but not eluates, from these columns exhibited significant suppressive activity for anti-poly(L-Phe,L-Glu)-poly-DL-Ala-poly-L-Lys, anti-azobenzenearsonate, and anti-sheep red blood cell antibody responses. Additional studies using eluates and filtrates from a variety of antigen-coated columns have demonstrated that suppressor factors of multiple antigenic specificities are present within SEB-induced supernatants. These studies suggest that SEB polyclonally activates antigen-specific suppressor cells which produce suppressor factors which specifically regulate the antibody response.

A non-cytotoxic suppressor of immunoglobulin synthesis and secretion by B cells of normal humans and patients with rheumatoid arthritis and systemic lupus erythematosus

A factor secreted by thymocytes of immunized rabbits totally suppressed both the initiation of, and ongoing synthesis and secretion of, lectin (PWM)-induced synthesis of IgM and IgG immunoglobulins by the circulating B lymphocytes of normal humans, and of twenty consecutive patients with rheumatoid arthritis and twelve consecutive patients with systemic lupus erythematosus. The suppressor factor, referred to as human Ig synthesis/secretion suppressor factor or HISSF, is not HLA restricted in its activity and is not cytotoxic to the circulating human mononuclear cells (B cells, T cells, Null cells and monocytes). It was demonstrated that T cells precultured with HISSF were transformed into suppressor cells which, when added to fresh cultures of autologous B cells, suppressed the synthesis and secretion of IgM and IgG. On the basis of its suppressive and non-cytotoxic properties in vitro, HISSF may be an effective immunosuppressant in the treatment of patients with autoimmune diseases.

Down-regulation of secondary in vitro antibody responses by suppressor T cells of mice treated with a tolerogenic conjugate of ovalbumin and monomethoxypolyethylene glycol, OVA(mPEG)13

In previous studies from this laboratory it was shown that OVA(mPEG)n conjugates induced: (i) tolerance in mice with respect to IgG and IgE antibody responses to dinitrophenylated OVA (DNP-OVA); and (ii) OVA-specific suppressor T (Ts) cells which could down-regulate a primary immune response in vivo. For the present study, we have developed an in vitro culture system for assessing the activity of Ts cells of mice tolerized by an OVA(mPEG)13 conjugate. Spleen cells from mice which had been primed with DNP4-OVA in Al(OH)3 gel were cultured with DNP4-OVA to induce a secondary antibody response in vitro. After 6 days, cells secreting anti-DNP antibodies of the IgG1 class were enumerated by an immunoenzymatic plaque-forming cell assay. Addition to the culture of T cells from mice treated with 3 i.p. injections of 500 micrograms of OVA(mPEG)13 resulted in a 29-61% reduction in the number of IgG1 anti-DNP antibody-forming cells, in comparison with the effect of T cells from mice treated with PBS. It was concluded that this tolerogenic conjugate induced splenic Ts cells which were capable of suppressing secondary in vitro anti-DNP responses.

T-cell clone anti-clone interactions. Effects on suppressor and helper activities

An experimental model of two interacting clones of T cells is described, which may be used for defining and exploring the T-cell immunoregulatory network. Mx9/9 is a CD4 clone bearing an antigen receptor recognized by the Mx9 anti-V beta 8 monoclonal antibody (MoAb). Anti-V beta 8 MoAbs activate and induce cell proliferation of this clone. Autologous clones were raised against Mx9/9 cells using the peripheral blood mononuclear (PBM) cells of the Mx9/9 clone donor (PBMjm). Some of these cloned anti-clone cells proliferated after stimulation with irradiated Mx9/9 cells, but not after stimulation with other autologous cloned T cells or heterologous PBM, suggesting that these clones recognize the T cell receptor (TCR) of the Mx9/9 cells. The proliferation of the Mx9/9 stimulated cloned anticlone cells was blocked by anti-class II MoAbs, indicating that the autoreactive clones recognize their target antigen in conjunction with HLA Class II products. The ability of clone Mx9/9 to proliferate after stimulation with anti-V beta 8 MoAb was inhibited when clone 121 cells were added to the cultures. However, clone 121 lost its suppressor function after 4 months in culture and instead gained the ability to enhance the proliferation of Mx9/9 cells in the presence of anti-V beta 8 MoAb. In contrast, clone 18 lacked suppressor activity at the early stage of the study but later acquired this function. We conclude that some autoreactive clones are not fully committed and may express more than a single function. Such cells cannot therefore be designated as 'suppressor cells', although they expressed suppressor potential at certain stages.

Two types of suppressor T cells that inhibit delayed-type hypersensitivity to Mycobacterium intracellulare in mice

Mycobacterium intracellulare Mino grows progressively in the organs of C57BL/6 mice. When C57BL/6 mice were injected with strain Mino, very weak or almost no delayed-type hypersensitivity (DTH) to the specific antigen, M. intracellulare purified protein derivative, was observed. The DTH response was enhanced by cyclophosphamide pretreatment, indicating that some suppression mechanism(s) might be involved in DTH. In cell transfer experiments it was shown that two types of suppressor T cells, afferent type (TS-Aff) and efferent type (TS-Eff), are induced in the spleens of Mino-infected mice. TS-Aff were detected from the early stage to the late stage of infection. TS-Eff were detected only in the late stage of infection. These two types of suppressor T cells were both Thy-1 positive and Lyt-2 positive; however, TS-Aff seemed to be I-J positive, and TS-Eff seemed to be I-J negative. Cross-reactivity in suppression was observed between Mino and Mycobacterium bovis BCG but not between Mino and sheep erythrocytes. DTH to Mino and BCG was not cross-reactive. The possible role of suppressor T cells in M. intracellulare infection is discussed.

Induction of antigen-specific T suppressor cells by soluble Paracoccidioides brasiliensis antigen

In naturally acquired paracoccidioidomycosis, patients have depressed in vivo and in vitro cell-mediated immune (CMI) responses to Paracoccidioides brasiliensis antigen. In addition, it has been reported that these patients have significant levels of circulating paracoccidioidal antigen in their sera. The primary purpose of this investigation was to assess the effects of P. brasiliensis antigen on the CMI responses in a mouse model. On the basis of findings with other fungal agents, we predicted that circulating paracoccidioidal antigen may be inducing suppressor cells which modulate the CMI response. In this study, we show (i) that a soluble P. brasiliensis culture filtrate antigen (Pb.Ag) emulsified in complete Freund adjuvant and injected subcutaneously into mice induces reasonably high levels of delayed-type hypersensitivity (DTH) in CBA/J mice; (ii) that Pb.Ag elicits DTH reactions specific for P. brasiliensis when injected into footpads of immunized mice; and (iii) that an intravenous injection of Pb.Ag induces a population of lymph node and spleen cells which, upon adoptive transfer, suppress the afferent limb of the DTH response to paracoccidioidal antigen. The afferent suppressor cells can be detected in spleens as early as 5 days after Pb.Ag treatment, are present in significant numbers by 7 days in both spleens and lymph nodes, and are virtually absent by 14 days. In contrast, at 14 days after antigen injection, efferent suppressor cells were detected in spleens and lymph nodes. The Pb.Ag-induced afferent suppressor cells specifically inhibit the antiparacoccidioidal DTH response. They are nylon wool-nonadherent cells, and their activity is abrogated by anti-Thy-1 and complement treatment, indicating that they are T lymphocytes. The phenotype of these afferent suppressor T cells is L3T4+ Lyt-1+2- I-J+. The Pb.Ag-specific suppressor cells described in this paper are similar to the Ts1 cells in the azobenzenearsonate, 4-hydroxy-3-nitrophenyl acetyl, and cryptococcal models of suppression of the DTH response and to the afferent suppressor cells in the dinitrofluorobenzene contact sensitivity system.

Comparison of gamma-interferon and alloantigen-induced T cell factors in the induction of MHC class II antigen expression and in the modulation of the immunogenicity of lymphocyte-free rat bone marrow

In a rat model, we compared the effects of various soluble products released by T cells, such as the unspecifically acting gamma-interferon or the newly detected alloantigen-induced factors that specifically act on nonlymphoid, hemopoietic bone marrow cells. We found two types of reactivity patterns with regard to the induction of MHC class II antigen expression on these cells. The very same patterns could be demonstrated when we investigated the modulation of their stimulatory capacity, i.e., their immunogenicity in a T proliferation assay. These findings are discussed in relation to the increasing incidence of immunologically mediated graft rejections in clinical bone marrow transplantation following T cell purging.

Production and assay of ovine T cell growth factor by concanavalin A stimulated peripheral blood leukocytes

Conditions for the production and assay of ovine T cell growth factor (TCGF) activity were evaluated. Peripheral blood leukocytes were stimulated with concanavalin A (Con A) in the presence of 2% autologous serum or serum-free media. Supernatants were harvested after 30 hr and concentrated for further characterization. A 28 hr proliferation assay with 2.5 X 10(4) 24 hr Con A blasts per well was optimal for detection of TCGF. Peak TCGF activity occurred with a 30-37 KD molecular weight fraction. Production and assay of TCGF were performed under autologous conditions to reduce background stimulation which occurred when fetal bovine serum was present. This methodology required no cell lines or inbred animals and should be adaptable to the study of immunostimulatory molecules of other outbred species.

Visualization of anti-I-J antibody binding sites on bone marrow-derived macrophages

I-J antigens on BMDM were visualized by immunofluorescence. Nonspecific binding of IgG antibody to Fc receptors was eliminated by the pretreatment of the antibody with anti-mouse IgG Fc portion antibody.

Production of suppressor factor by T-cells from mice immunized with pneumococcal polysaccharide

Factor(s) derived from plate purified T-cell cultures obtained from mice 16 hr after immunization with Type III pneumococcal polysaccharide (SSS-III), suppressed the antibody response to SSS-III. Such suppression was antigen specific. Adsorption of the suppressor factor (SF) with SSS-III covalently bound to Sepharose 4B column did not alter the ability of SF to suppress the antibody response. However, adsorption of SF with Ig+(B) cells taken from mice 48 hr after immunization with an immunogenic dose (0.5 ug) of SSS-III, completely removed the suppressive activity. Suppression of the antibody response was observed only when SF was administered 24 hr before to 24 hr after immunization with SSS-III. These results suggest that antigen specific suppressor T cells release soluble factor(s) which acts directly on antigen-stimulated B cells or may inhibit the induction of amplifier T-cells.

Sequence and expression of transcripts of the T-cell antigen receptor alpha-chain gene in a functional, antigen-specific suppressor-T-cell hybridoma

We have detected rearrangement and expression of a gene encoding a T-cell antigen receptor alpha chain in the keyhole limpet hemocyanin (KLH)-specific, inducible suppressor-T-cell (Ts) hybridoma 34S-281 (BW5147 lymphoma-C57BL/6Ts) by using alpha-chain cDNA clones isolated from this Ts hybridoma. The cDNA clones have a restriction length polymorphism in the constant region that identifies them as being of C57BL/6 origin. The cDNA sequence has an ATG start codon for an open reading frame including variable, joining, and constant gene segments. Furthermore, the Ts alpha-chain gene transcripts were detected on membrane-bound polysomes by RNA blot analysis using a variable-region fragment from one of the alpha-chain cDNA clones as probe, suggesting that they are actively translated in the Ts hybridoma. As the beta-chain gene is deleted in all Ts hybridomas analyzed, and since a disulfide-linked dimer is detectable by two-dimensional NaDodSO4/PAGE of lysates of surface-radioiodinated Ts, we suggest that Ts antigen receptors are either alpha-chain homodimers or heterodimers composed of the alpha chain in association with an undefined chain.

Immunoregulation of lysozyme-specific suppression. III. Epitope-specific amplification of immunosuppression induced by monoclonal suppressor-T-cell products

The hen egg-white lysozyme (HEL)-specific suppression induced by soluble molecules produced by a monoclonal T-cell lymphoma line (LH8-105) obtained from HEL-specific suppressor T lymphocytes has been examined. Injection of I-J+ molecules from LH8-105 cell culture supernatant (TsFa) in HEL-primed mice during the afferent phase of the response induced Lyt-2+ second order suppressor T (Ts) cells which, upon transfer into HEL-CFA-primed syngeneic recipients, inhibit the delayed-type hypersensitivity (DTH) response to HEL. Transfer of spleen cells from TsFa-injected mice primed with HEL or human lysozyme suppresses the DTH response to HEL in recipient mice whereas this response is not affected by cell transfer from ring-necked pheasant egg-white lysozyme (REL)-primed and TsFa-injected mice, indicating that induction of second order Ts by TsFa is specific for a lysozyme epitope including phenylalanine at position 3. Fine antigenic specificity of second order Ts-cell induction is confirmed by similar results obtained upon injection of TsFa in mice primed with HEL N-terminal synthetic peptide or with an analog in which, as in REL, phenylalanine has been substituted by tyrosine at position 3. The same fine antigenic specificity observed in the induction of second order Ts cells is also present in the expression of TsFe suppressive activity. The similar antigenic specificity of Tsa and Tse suggests that Tse cells could result from amplification of the Tsa cell population or these two cell subsets could reflect different maturation stages of the same cell type rather than distinct T-cell populations activated in cascade.

Interaction of idiotype-specific T suppressor factor with the hapten-specific third-order T suppressor subset results in antigen-nonspecific suppression

The interaction between the third-order T suppressor (Ts3) cell and the idiotype (Id)-specific second-order Ts factor (TsF2) was studied in the phenyltrimethylamino (TMA) hapten system. The experimental system which we used allowed the independent analysis of induction and activation requirements of Ts3. The procedure consisted of inducing the Ts3 in vivo and activating the enriched T-cell populations containing Ts3 in vitro with TsF2. The suppressive potential was then tested in mice previously primed for delayed-type hypersensitivity responses which were also treated with cyclophosphamide to deplete Ts3 and other drug-sensitive Ts cell types. Using this experimental system, it was found that the Id-specific TsF2 was required for the in vitro activation of Ts3. Furthermore, the TsF2 activated only the homologous and not heterologous antigen-primed Ts3-containing T cells and moreover, the target of TsF2 was found to be the Ts cells bearing hapten-specific receptors. Once the TMA hapten-specific Ts3 was activated with TsF2, the ensuing suppression was antigen nonspecific. The data demonstrate that the Ts3 represents a final effector Ts cell type in the TMA system.

A unique polypeptide on avian antigen-specific suppressor T-cell radioiodinated in situ by antigen-lactoperoxidase conjugates

Antigen-specific receptors of B- or T-cells were selectively radiolabeled among the spleen cells from either human gammaglobulin immunized normal or bursectomized agammaglobulinemic chickens. Selective in situ radioiodination was accomplished by employing lactoperoxidase (LPO) covalently linked to antigen (Ag). Ag-specific receptors on B- or T-cells were allowed to bind Ag-LPO conjugates via the Ag portion of the conjugates and then to be selectively catalyzed for iodination by the LPO portion of the bound Ag-LPO conjugates. Radioiodinated cells were either processed for autoradiography to detect Ag-binding cells directly under the microscope or solubilized with detergents for protein analysis with two-dimensional (2-D) gel electrophoresis. On a cellular level, Ag-binding B- and T-cells were selectively radiolabeled and clearly visualized via autoradiography. On a molecular level, selectively radiolabeled Ag-specific membrane immunoglobulin of B-cells was demonstrated on 2-D gel autoradiographs. Furthermore, a unique polypeptide of Ag-specific T-cells with a reduced apparent mol. wt of 27 K and an apparent pI of 5.5-5.7 was demonstrated on 2-D gel autoradiograms. The 27 K molecule appears to be a T-cell receptor component itself, or a closely associated molecule.

A primary in vitro antibody assay for antigen-specific T-suppressor factor: cross-suppression of TNP-specific antibody responses by TMA-specific TsF1

We have previously shown that phenyltrimethylammonium (TMA)-specific, first-order suppressor T cells (Ts1) and soluble factors extracted from these cells (TsF1) can suppress delayed-type hypersensitivity (DTH) responses. The TsF1, as monitored in the DTH system, was characterized and found to be a single-chain, antigen-binding, I-J+, and Id+ molecule. To monitor TsF1 in an efficient manner, an in vitro antibody system was developed. The studies show that in vitro stimulation of naive A/J spleen cells with the thymic-independent antigen, Brucella abortus, to which TMA and trinitrophenol (TNP) or fluorescein (FL) are coupled (TMA-BA-TNP or TMA-BA-FL), induces significant numbers of anti-TNP or anti-FL plaque-forming cell (PFC) responses. The addition of TMA-specific TsF1 results in the cross-suppression of 30-50% of the total anti-TNP and FL PFC responses. This activity is antigen (TMA) dependent since suppression occurs only when the TMA ligand is present in the culture media. Analysis of the TNP-specific PFC responses in nonsuppressed cultures revealed that 20-35% of the PFC bear the cross-reactive idiotype(s) (CRI) normally associated with anti-TMA antibodies. In cultures containing TMA-TsF1, CRI+PFC are suppressed by 90-100% while the CRI-PFC are suppressed only by 10-30%. Our studies further show that an induction-phase, antigen-binding, CRI+, and I-J+ single-chain factor is responsible for the observed in vitro suppression. The possibility of utilizing this assay to monitor a variety of antigen-specific suppressor factors is discussed.

Antigen-specific, I-A-restricted suppressor hybridomas with spontaneous cytolytic activity. Functional properties and lack of rearrangement of the T cell receptor beta chain genes

T suppressor (Ts) hybridomas were produced by fusion of the III/4 T cell hybridoma with splenic T cells from CBA mice tolerized with subimmunogenic doses of bovine serum albumin (BSA). Both the Ts hybridoma cells and a suppressor factor (TsF) inhibited in an antigen-specific and I-Ak-restricted fashion the in vitro proliferative response of BSA-immunized lymph node cells. In addition to the suppressive activity, the hybridoma lines displayed spontaneous cytotoxicity against various tumor targets. The isolation of Ts subclones that are suppressive but not cytolytic, as well as the existence of the noncytolytic TsF, indicates that suppression of antigen-specific T cell proliferation is not dependent on cytolytic activity. The Ts hybridomas were I-A restricted, as are many T helper cells. Therefore, a potential similarity with respect to antigen receptor genes was expected. Southern blot analysis with a probe specific for genes encoding the beta chain of the T cell receptor on T helper and T killer cells revealed no rearrangement of the beta genes in the Ts cells. The data imply that neither the antigen receptor on the I-A-restricted Ts cells nor the receptor involved in the cytolytic interaction with tumor targets use the same beta chain constant region as T helper and T killer cells.

T cell regulation of B cell activation. Lyt-1+,2-T cells modify the MHC-restricted function of heterogeneous and cloned T suppressor cells

Previous studies have shown the existence of both heterogeneous Lyt-1-,2+ suppressor (Ts) cells and cloned Lyt-1+,2- Ts cells which, despite the difference in their Lyt phenotypes, functioned in a similar antigen-specific and major histocompatibility complex (MHC)-restricted fashion to suppress the antibody responses generated by cloned helper T (Th) cells and hapten-primed B cells. Our studies were carried out to assess in further detail the genetically restricted cell interactions that mediate this immune response suppression. We show that the activation of both heterogeneous and cloned Ts cells is antigen-specific and MHC-restricted under our experimental conditions. After appropriate activation, the effector function of both cloned Lyt-1+,2-Ts cells and heterogeneous Lyt-1-,2+ Ts cells was also antigen-specific. In contrast, once activated, Ts cells suppressed the responses generated by cloned Th cells and hapten-primed B cells in an MHC-unrestricted fashion. We also showed, however, that a population of unprimed Lyt-1+,2-T cells was able to significantly alter the genetic restriction requirements for Ts cell function. The activity of this population was itself MHC-restricted, and was observed only when the unprimed Lyt-1+,2-T cells shared the MHC restriction specificity of the cloned Th cells functioning in a given response. When these requirements were satisfied, Lyt-1+,2- T cells significantly modified the suppression mediated by both heterogeneous and cloned Ts cells, resulting in suppression that was then MHC restricted in its effector function as well as in its activation requirements. Thus, our findings suggest that the observed MHC restriction in Ts function is the result of a complex interaction involving Ts cells, Th cells, and an additional population of MHC-restricted Lyt-1+,2- T cells. This newly characterized activity of Lyt-1+,2- T cells functionally resembles that of an MHC-restricted contrasuppressor population that selectively blocks a pathway of MHC-unrestricted Ts activity, while leaving intact susceptibility to MHC-restricted Ts effects.

I-J as a restriction element in the suppressor T cell system

This review attempts to sort out the differences between macrophage and T cell I-J determinants. We propose that suppressor T cells have receptors for self-I-J determinants which are expressed on macrophage-like accessory cells. The I-J determinants associated with accessory cells are responsible for the selection of the Ts receptors. Although the major histocompatibility complex is involved in the selection of Ts receptors, the receptors themselves need not be encoded by genes which reside within the MHC. In fact, the molecular genetic evidence presently available has established that suppressor T cell factors do not express gene products associated with the postulated I-J region of the H-2 complex. In spite of the failures of biochemists and molecular geneticists to identify I-J genes and gene products, there is extensive biological data demonstrating the existence of I-J. The activity of anti-I-J reagents has been verified by numerous laboratories. Sera containing anti-I-J activity have been prepared in many strain combinations. Immunization between a variety of strains differing at the purported I-J region produce active anti-I-J antibodies (Murphy et al. 1976, Tada et al. 1976, Pierres et al. 1977, Tada et al. 1978). Furthermore, in many suppressor cell systems the interactions of Ts cells and factors are restricted by I-J (Tada & Okumara 1980, Sorensen & Pierce 1982, Green et al. 1983, Dorf & Benacerraf 1984). Most investigators who have attempted to detect I-J have analyzed T cells. Since we propose that T cells express a complementary anti-I-J receptor, subsequent efforts at identifying I-J should include analysis of macrophage I-J determinants. In spite of extensive biological data, we still do not know if I-J is a protein, carbohydrate or lipid. In addition, the role of H-2 in determining I-J structure is unknown. Nevertheless, the overwhelming biological data demonstrate that I-J is an important structure for suppressor T cell interactions. Much remains to be accomplished, including the characterization of I-J products and locating the I-J genes.

Correlation between immunosuppressive activity and translation regulatory activity

An immunoglobulin negative material from the eluate of an anti-idiotype immunosorbent column [1] exhibited potent immunosuppressive activity. This material also inhibited the translation of globin mRNA in a cell-free reticulocyte lysate system. The translation inhibitory activity of this material was not attributable to nucleases which were separable by a blue-dextran agarose column. Further correlation between immunosuppressive activity and translation inhibitory activity was observed when GTP or GTP analogue was included in experimental systems. These results suggest that the immunosuppressive factor (or factors) may contain a translation inhibitory factor. The biochemical mechanism of immunosuppression is discussed.

Partial purification and characterization of B cell growth factor constitutively secreted by human T-cell hybridoma

Human T cell hybridomas were established by fusion of PHA-activated PBL with the 8-azaguanine resistant human T-leukemic cell line CEM-CM3. High levels of B cell growth factor (BCGF) activity were detected in the supernatants of hybridoma C8-2B2 and its subclones. Hybridoma C8-2B2, in addition to the Leu 3a, also expressed the OKT11 surface marker which was not detectable on the parent CEM-CM3 cells. BCGF from the culture supernatant was purified by combined use of salt fractionation and gel filtration to 36.6 fold with 23.9% recovery of activity. The BCGF produced by hybridoma C8-2B2 has a molecular weight range of 16,000-20,000 in two major electrophoretically different forms with pI values of 6.4 and 7.4.

Evaluation of plasma C3d and immune complex determinations in the assessment of disease activity of patients with rheumatoid arthritis, systemic lupus erythematosus, and spondylitis ancylopoetica

Patients with rheumatoid arthritis, systemic lupus erythematosus, and spondylitis ancylopoetica were examined, along with healthy controls, for C3d plasma levels, circulating immune complexes, C3 serum levels, and CRP. Immune complexes were determined using a Clq binding assay, a 2.75% PEG precipitation technique, including the analysis of IgG and C3, and a new laser nephelometric latex test. C3d plasma levels were significantly (P less than 1%) elevated in all groups of patients as compared to controls. With regard to the demonstration of circulating immune complexes, the PEG precipitation method discriminated best between patients and the control population. It was not possible to differentiate between the different disease entities with neither C3d serum levels or immune complexes. Concerning the assessment of disease activity, none of the evaluated parameters alone appears to be of clinical relevance. The individual application of more than one immune complex assay in combination with the measurement of C3d serum levels must be recommended if disease activity is to be assessed.

Acetylcholine receptor-specific suppressive T-cell factor from a retrovirally transformed T-cell line

In both experimental and human myasthenia gravis an impairment in the immune regulation leads to an increased synthesis of antibodies against the nicotinic acetylcholine receptor (AcChoR). The present work reports the establishment of an AcChoR-specific suppressive T-cell line obtained by viral transformation of AcChoR-enriched murine T lymphocytes. Enriched T cells from Torpedo AcChoR-primed mice, prestimulated in vitro with antigen, were infected with radiation leukemia viruses and injected intravenously in congeneic recipient mice. Six months later lymphomas were observed in 20% of the injected mice and two of them, of donor origin, were established as permanent continuous cell lines in vitro. One of these lines, named LA41, expresses Thy-1.2, Lyt-2, and I-Jb surface markers. Culture supernatants of LA41 cells suppress the antigen-specific in vitro proliferation of Torpedo AcChoR-primed lymphocytes. This suppression is antigen-specific since the response induced by fetal calf AcChoR and by other antigens is not affected by addition of LA41 culture supernatant in the proliferative assay. LA41 culture supernatant injected in vivo at the time of antigen-priming suppresses also significantly the production of anti-AcChoR antibodies but not the synthesis of antibodies against other antigens--i.e., fetal calf AcChoR or alpha-bungarotoxin. These data show that LA41 cells constitutively produce Torpedo AcChoR-specific suppressor factor.

Partial characterization of T cell components related to defined VH (VT) markers

Certain antigen-binding surface molecules and factors of T cells possess serological determinants related to immunoglobulin (Ig)-heavy-chain-variable regions (VH). We obtained sufficient quantities (greater than 100 micrograms) of homogenous VH-related T-cell molecules (VTM) for biochemical studies from normal murine thymocytes and by growing large quantities of monoclonal T-cell leukemia lines expressing the determinants. A solid phase immune adsorbent prepared from the IgG fraction of rabbit anti-IgT serum was used to isolate VTM from formic acid-solubilized T cells. The VTM from murine thymocytes and T-cell lines had Mr of 65,000-68,000. The VTM from distinct cell lines differ by isoelectric focusing and resolution of tryptic peptides indicating clonal restriction. VTM lack conventional light- or heavy-chain-constant region determinants but cross-react with antisera directed against defined VHa allotypes and JH peptides. The detection of a cross-reaction with a synthetic JH peptide is consistent with recently published data identifying JH-related sequences in putative T-cell receptor genes. The amino acid compositions of the VTM were distinct from those of mammalian Ig, major histocompatibility complex (MHC) antigens, and viral glycoproteins, but significant similarities occur with Ig V regions or heavy chains of primitive vertebrates. The results indicate that the VH-bearing T-cell products are not classical Ig, but bear limited VH-cross-reactive determinants.

Antigen-specific suppression of collagen arthritis by adoptive transfer of spleen cells

Wistar-Furth (W-F) rats were given 10(9) syngeneic spleen cells, suspended in Hanks' balanced salt solution (HBSS), intravenously on Day 0 to investigate the mechanisms involved in antigen-specific suppression of collagen arthritis. These cells were pooled from W-F donors which had been injected iv on Days -21, -14, and -7 with rat red blood cells (RBC) coupled with glutaraldehyde to either native chick type II collagen, denatured type II collagen, or native type I collagen. All recipients were immunized with an emulsion of native type II collagen in incomplete Freund's adjuvant on Day 1 to induce collagen arthritis. There was a decreased incidence of arthritis, by clinical and radiographic assessments, in rats receiving spleen cells from donors previously administered native type II collagen-coupled RBC compared to those given spleen cells obtained from donors treated with denatured type II or native type I collagen-coupled RBC [18 of 30 (60%) arthritic vs 20 of 20 (100%) and 19 of 20 (95%) arthritic, for the three groups, respectively, P less than 0.01 for both comparisons]. The incidence of arthritis in 35 rats administered HBSS iv 1 day prior to immunization (83%) and 10 immunized rats given no iv injections (100%) was also significantly higher (P less than 0.05) than the incidence in the antigen-relevant experimental group. Hemagglutinating antibody titers and delayed-type hypersensitivity (DTH) to collagen were lower in the recipients of cells from donors administered native type II collagen-coupled RBC, whereas IgG antibody titers to collagen were unaltered. These results demonstrate that passively transferred spleen cells can attenuate collagen arthritis and sensitization in an antigen-specific manner.

Quantitation of helper factor activity. II. Inhibition of antibody binding

A sensitive direct assay has been developed to quantitate antigen specific helper factors (ThF). The assay depends on the ability of ThF to block the binding of free antibody to immobilized antigen. It has been used to follow the course of purification of ThF produced in short-term cultures of in vitro primed helper cells and purified by affinity chromatography on antibody and antigen immunoabsorbents. The identity of the ThF was confirmed by assaying its biological activity and by its reactivity with anti-Ia antibody and with a monoclonal anti-ThF.

Subnormal expression of cell-mediated and humoral immune responses in progeny disposed toward a high incidence of tumors after in utero exposure to benzo[a]pyrene

Pregnant mice were exposed to 150 micrograms benzo[a]pyrene (BaP) per gram of body weight during fetogenesis (d 11-17 of gestation) and the progeny were assayed for humoral and cell mediated immune responses at different time intervals after birth. Immature offspring (1-4 wk) were severely suppressed in their ability to produce antibody-(plaque-) forming cells (PFC) against sheep red blood cells (SRBC) and in the ability of their lymphocytes to undergo a mixed lymphocyte response (MLR). Lymphocytes from these progeny showed a moderate to weak capacity to inhabit production of colony-forming units (CFU) in host spleens following transfer with semiallogeneic bone marrow (BM) cells into lethally X-irradiated recipients syngeneic to the BM (in vivo graft-versus-host response, GVHR). A severe and sustained suppression in the MLR and the PFC response occurred from the fifth month up to 18 mo. The in vivo GVHR, also subnormal later in life, was not as severely suppressed as the other two parameters. Tumor incidence in the BP-exposed progeny was 8- to 10-fold higher than in those encountering corn oil alone from 18 to 24 mo of age. These data show that in utero exposure to the chemical carcinogen BaP alters development of components needed for establishing competent humoral and cell-mediated functions of the immune apparatus and leads to severe and sustained postnatal suppression of the defense mechanism. The immunodeficiency exhibited, particularly in the T-cell compartment (MLR, GVHR), before and during the increase in tumor frequency, may provide a favorable environment for the growth of nascent neoplasms induced by BaP.

Contrasuppression: the second law of thymodynamics, revisited

The data discussed here touch upon several issues in the evolving story of T cell contrasuppression, the underlying theme being that of heterogeneity. First, there is the issue of function. We are considering here only those cells that affect the function of secretory differentiation. We have evidence that different contrasuppressor cells exist for clone growth, but have not yet studied them in the same depth as those for secretory differentiation. Second, there is the important issue of target cells. In this article by Green and Gershon it is pointed out that there is clear evidence that contrasuppressor effects can work by protecting helper cells from suppressor cell effects in vitro. On the other hand, direct additional inhibition of the suppressor cells themselves has not been excluded. The latter point is also true in our system. However, we must suppose for the sake of simplicity in many of our experiments that if suppressors are not the target of the contrasuppressor effects then the B cells themselves probably are. This is because the tumor cells engage in a spontaneous rate of growth and differentiation in the absence of help or suppression. When T cell-dependent, specifically triggered effects reduce this spontaneous behavior, then a suppressive effect must have been delivered directly to the B cells. This is a simplifying assumption which is attractive, but since the experiments are carried out in vivo and thus may be affected by some factors that we have not yet recognized, we are not confident on its "intuitive" appeal. A third issue revolves around triggering specificity. One of our contrasuppressors exhibits the phenomenon of carrier crossreactivity (CRCS) and is thus behaving in accord with expectations aroused by Green and Gershon in this review. The other cell is apparently quite carrier specific (SCS). The meaning of this is not at all clear, but its potential significance may somehow be related to a sort of "mirror image" relationship of the two cells. Thus, for example, in other experiments not discussed here, we have noted that the CRCS binds to 315 protein-coated plates, but as noted here counteracts a suppressive effect which is generated by cells which do not adhere to these plates. In contrast to SCS does not bind to 315 plates and yet, as noted here, appears to counteract a suppressor effect generated by cells which do adhere to 315 plates.(ABSTRACT TRUNCATED AT 400 WORDS)