Nature of T cell-macrophage interaction in helper cell induction in vitro. I. Evidence for genetic restriction of T cell-macrophage interactions prior to T cell priming

The separation of immunocyte subpopulations by use of various lectins

The use of lectins for the enrichment of various lymphocyte subpopulations was investigated. Bauhinia purpurea lectin (BPA) was found to be effective for the enrichment of B cells, and the B cells thus obtained were further fractionated with lentil lectin into subsets showing high and low responses to dextran sulfate. The ability of various lectins to selectively induce suppressor T cell activity or helper T cell activity was also examined. The suppressor T cells thus induced were enriched peanut lectin and, conversely, the helper T cells were enriched with Limulus polyhemus lectin. This method was applied to analysis of age-dependent changes in the levels of suppressor and helper T cells in autoimmune-prone mice. Cytotoxic T cells induced in an allogeneic mixed lymphocyte culture were enriched with Dolichos biflorus lectin (DBA). These cytotoxic T cells showed a specific killing effect in vitro. However, when spleen cells of tumor-bearing mice were fractionated by use of DBA, the DBA- cells mediated the regression of the tumors in vivo. BPA was also found to be effective for the enrichment of the interleukin-2-producing T cell subset and macrophage precursor cells. Using this technique, bone marrow cells of autoimmune-prone MRL/1 mice were found to be rich in macrophage precursor cells.

Differentiation markers and accessory function of murine macrophages derived from cultured bone-marrow stem cells

Murine bone-marrow cells cultured in the presence of colony-stimulating factor from mouse-lung-conditioned medium give rise to macrophages which function as accessory cells in antigen-specific T helper cell induction. Virtually all Ia+ bone-marrow stem cell-derived macrophages express determinants encoded in the I-A subregion. A second set of macrophages bears I-A as well as I-E/C-endoced determinants. The products of the I-A and I-E/C subregion, but not those of the I-J subregion, are involved in T helper cell induction.

Characterization and expression of H-21 region gene products on bone marrow-derived macrophages

Antigen-presenting macrophages (M phi) were derived from day 7 cultures of bone marrow stem cells using L cell conditioned medium. The adherent bone marrow-derived macrophages (BMM phi) were 100% esterase-positive, 95% positive for C3 receptors, 93% positive for Fc receptors, and 95% actively phagocytic. Indirect immunofluorescence using anti-Ia monoclonal antibodies resulted in 60% Ia-positive BMM phi on day 7 of stem cell culture. BMM phi could stimulate mixed lymphocyte reaction (MLR) proliferation across an I-A subregion difference, but not across I-J subregion differences. This contrasted with splenic M phi which stimulated MLR proliferation across both an I-A and I-J subregion difference. The apparent lack of I-J subregion determinants on BMM phi correlated with their ability to function as antigen-presenting cells. In these experiments, BMM phi effectively reconstituted the trinitrophenyl-specific IgM plaque-forming cell (PFC) response of B cells but not the primary burro red blood cell (BRBC)-specific IgM-PFC response of M phi-depleted spleen cells. When BMM phi were added to BRBC-primed T and B cells, they reconstituted the secondary IgG PFC response to levels obtained using splenic M phi. These experiments relate the differential expression of H-21 region determinants on antigen-presenting cells with their functional capacity.

Studies of immune functions of patients with systemic lupus erythematosus: antibodies to desialized, rather than intact, T cells preferentially bind to and eliminate suppressor effector T cells

Patients with systemic lupus erythematosus (SLE) were found to have in their plasma antibodies specific for desialized T cells. Adsorption studies with intact or desialized T cells indicated that SLE anti-T cell antibodies consisted of two populations with different target cell specificities, one capable of recognizing unique determinants on desialized T cells and another able to bind to both intact and desialized T cells. Normal T cells did not remove the antibodies specific for desialized T cells. moreover, the antibodies to desialized T cells were not removed by adsorption with either desialized non-T cells or desialized erythrocytes. Thus, the antibodies to desialized T cells recognize a determinant that is unique to a T cell subset and also includes a sugar. Inhibition studies with various sugars indicated that lactose was the most potent inhibitor of antibody binding. The anti-desialized T cell antibody appears to recognize a T cell determinant which includes lactose, probably in the form of a beta-galactosyl residue, but which also includes additional T cell determinants. The antibodies to desialized T cells were found to bind preferentially to concanavalin A-induced autorosetting T cells, which had been already demonstrated to contain suppressor effector cells. Indeed, such antibodies were effective in eliminating suppressor effector function without interfering with T cells necessary for such activation (such as precursor or inducer cells). Finally, studies of patients with SLE yielded a highly significant correlation (r = 0.92) between impaired suppressor effector function of their cells and the presence of antibodies to desialized T cells in their plasma.

Immune response genes controlling responsiveness to major transplantation antigens. Specific major histocompatibility complex-linked defect for antibody responses to class I alloantigens

We have identified two major histocompatibility complex (MHC)-linked Ir genes that control the antibody response made by rats against class I major alloantigens. We have named these genes Ir-RT1Aa and Ir-RT1Ac. These Ir genes determine responsiveness of the immunized animal in a typical codominant fashion. There is no evidence so far for trans-complementation between low-responder haplotypes. Detailed studies of Ir-RT1Aa indicate that it controls the antibody response to at least two distinct alloantigenic determinants on RT1Aa molecules. These class I molecules thus behave like hapten-carrier conjugates when the response against the carrier is under Ir gene control. Analysis of the origin of alloantibody-forming cells in tetraparental radiation chimeras indicates that Ir-RT1Aa must control the provision of effective help to B cells. In many respects therefore, the properties of Ir-RT1Aa are broadly similar to those described for Ir genes controlling antibody responses to conventional antigens. The existence of apparently conventional Ir genes controlling the antibody response to major alloantigens strongly suggest that the processing of these transmembrane molecules by host antigen-presenting cells is a prerequisite for immune induction, and that it is the MHC of the responder rather than that of the allograft to which T helper cells are restricted in alloimmune responses in vivo.

Separation of concanavalin A-induced human suppressor and helper T cells by the autologous erythrocyte rosette technique

Very few normal human peripheral blood T cells are capable of binding autologous erythrocytes to form rosettes, whereas in the T cell population activated by concanavalin A (Con A) the autorosette levels are markedly enhanced. Fractionation of the Con A-activated T cells with autologous erythrocytes into autorosetting and nonrosetting cells demonstrates that suppressor, but not helper, activity resides in the autorosetting population, whereas the reverse is true of the nonrosetting population. Both these activities are found to be Con A dependent. The Con A-induced human suppressor cells can be identified and separated from the Con A-induced human helper cells by the autorosette technique. Studies on the surface properties of autorosetting and nonrosetting T cells indicate that there is little correlation between the activated suppressor and helper T cell subsets defined by autorosette technique and either those defined by monoclonal antibodies (which are able to distinguish these subsets in the resting but not activated T cells) or those defined by Fc receptors. Since the autorosetting T cell population (which acts as suppressor cells) bears receptors for peanut agglutinin, the nature of Con A-induced human suppressor cells appears to be analogous to that of Con A-induced murine suppressor cells.

Nature of macrophage-T cell interaction in secondary helper cell generation in vitro. Genetic restriction of macrophage-T cell interaction, which determines T-B genetic restriction

To investigate the histocompatibility requirements for the macrophage-T cell interaction in the secondary antibody response, splenic T cells from antigen (carrier)-primed F1 hybrid mice were restimulated in vitro with carrier-pulsed F1, parental or allogeneic macrophages. Surviving T cell were cocultured with hapten-primed F1 or parental "B cells" and restimulated with the appropriate hapten-carrier conjugate. The IgG antibody-forming cell response was then measured using a plaque assay. Mapping of the genetic restriction was performed by use of different strain combinations. T helper cells could be restimulated in the presence of macrophages only provided they shared the I-A subregion of the major histocompatibility complex with the F1 T cells frm F1 hybrids restimulated with parental or I-A-identical macrophages were shown to only cooperate with parental B cells of the same I-A haplotype as the macrophages used for restimulation. The defect was at the level of the macrophage, as addition of macrophages of the I-A haplotype used for the restimulation culture reconstituted ability of F1 helper cells to cooperate with the I-A-nonidentical B cells.

Effects of blocking helper T cell induction in vivo with anti-Ia antibodies. Possible role of I-A/E hybrid molecules as restriction elements

To examine the role of Ia antigens in controlling T cell activation in vivo, unprimed (CBA X B6)F1 (H-2k X H-2b) T cells were positively selected to sheep erythrocytes (SRC) for 5 d in irradiated F1 mice in the presence of large doses of anti-Iak antibody. With selection in the presence of broad-spectrum anti-Iak antibody (A.TH anti-A.TL antiserum), the activated T cells were markedly reduced in their capacity to collaborate with either B10.BR (I-Ak I-Bk I-Jk I-Ek I-Ck) (kkkkk) or B10.A(4R) (kbbbb) B cells but gave good helper responses with B10 (bbbbb) and (B10 X B10.BR)F1 B cells. Because there was no evidence for suppression, these findings were taken to imply that the anti-Iak antibody bound to Ia determinants on radioresistant macrophagelike cells of F1 host origin and blocked the activation of the IGk-restricted subgroup of F1 T cells but did not affect activation of the Iab-restricted T cell subgroup. Analogous experiments in which F1 T cells were selected to SRC in F1 mice in the presence of monoclonal anti-I-Ak antibody gave different results. In this situation, the reduction in T cell help for Iak-bearing B cells applied to B10.A(4R) B cells but not to B10.BR B cells. With selection of F1 T cells in B10.A(4R) mice, by contrast, anti-I-Ak antibody blocked T cell help for both B10.A(4R) and B10.BR B cells. These data suggested that genes telomeric to the I-A subregion were involved in controlling T cell activation and T-B collaboration. Because no evidence could be found that I-B through I-C determinants per se could act as restrictions elements, the working hypothesis for the data is that Iak-restricted T cells consist of two subgroups of cells: one subgroup is restricted by I-A-encoded molecules, whereas the other is restricted by I-A/E hybrid molecules encoded by two separated genes situated in the I-A and I-E subregions, respectively. The notion that A/E hybrid molecules serve as restriction elements is in line with the findings of other workers that these molecules can act as alloantigens and control responses to certain antigens under double Ir gene control.

Gene complementation. Neither Ir-GLphi gene need be present in the proliferative T cell to generate an immune response to Poly(Glu55Lys36Phe9)n

The cellular requirements for immune response (Ir) gene expression in a T cell proliferative response under dual Ir gene control were examined with radiation-induced bone marrow chimeras. The response to poly(Glu55Lys36Phe9)n (GLphi) requires two responder alleles that in the [B10.A X B10.A(18R)]F1 map in I-Ab and I-Ek/Cd. Chimeras in which a mixture of the nonresponder B10.A parental cells (which possess only I-Ek/Cd) and the nonresponder B10.A(18R) parental cells (which possess only I-Ab) were allowed to mature in a responder F1 environment did not respond to GLphi, which suggests that at least one cell participating in the response needed to possess both responder alleles to function. When T cells from such A + 18R leads to F1 chimeras were primed in the presence of responder antigen-presenting cells (APC), the chimeric T cells responded to GLphi, which suggests that both responder alleles must be expressed in the APC but not necessarily in the T cell. Interestingly, acutely irradiated F1 animals were found not to be an adequate source of responder APC for priming the proliferating T cell because of the rapid turnover of peripheral APC after irradiation. In adoptive transfer experiments, T cell-depleted bone marrow had to be used as a source of responder APC. When bone marrow cells from (B10.A X B10)F1 responder animals were allowed to mature in a low-responder B10 of B10.A parental environment, neither chimera, F1 leads to A or F1 leads to B, could respond to GLphi. This demonstrated that the presence of high-responder APC, which derive from the donor bone marrow, was not sufficient to generate a GLphi response. It appears that in addition it is essential for the T lymphocytes to mature in a high-responder environment. Finally, B10.A(4R) T cells, which possess neither Ir-GLphi responder allele, could be educated to mount a GLphi-proliferative response provided that they matured in a responder environment and were primed with APC expressing both responder alleles. Therefore, the gene products of the complementing Ir-GLphi responder alleles appear to function as a single restriction element at the level of the APC. T cells that do not possess responder alleles are not intrinsically defective, because they could be made phenotypic responders if they developed in an environment in which responder major histocompatibility complex (MHC) products were learned as self and if antigen was presented to them by APC expressing responder MHC products.

Cooperation of murine F T and parental B lymphocytes in rejection of a xenogeneic tumour: adaptive differentiation of B lymphocytes?

The primary humoral immune response to rat Yoshida ascites sarcoma (YAS) grown in mice was used to study thymus-dependent (T) and bone marrow-derived (B) lymphocyte cooperation. It was shown that B6D2F1 T lymphocytes that do not cooperate with parental B lymphocytes enabled parental B lymphocytes from B6 leads to B6D2F1 radiation chimaeras to reject the tumour. However, when the bone marrow cells from B6 leads to B6D2F1 chimaeras were used to reconstitute parental B6 mice, these B6 leads to B6D2F1 leads to B6 mice lost their tolerance to D2 transplantation antigens, and their B lymphocytes were not able to cooperate with B6D2F1 T lymphocytes. In our search for the reasons for the failure of F1 T cells to be effective in parental and P leads to F1 leads to P TIR mice, rejection of F1 T cells was excluded because : (i) immune reactivity in TIR mice was found to be either absent or minimal; (ii) parental TIR mice did not produce any detectable cytotoxic antibodies after an intravenous injection of F1 splenic T cells; and (iii) YAS rejection was not induced at very high doses of F1 T cells. However, in a cell transfer system we were able to demonstrate that injection of spleen cells from parental TIR mice could thwart the successful cooperation of transferred F1 T cells with host B cells. Collectively, these data suggest that the changes of the collaborative potential of parental B cells as achieved in the F1 environment could be ascribed to 'adaptive' differentiation of B lymphocytes. It appears that the differentiation process that has rendered nonsyngeneic chimaeric cells able to cooperate was independent of the exogenous antigen.

Role of I-region gene products in macrophage induction of an antibody response. II. Restriction at the level of T cell in recognition of I-J-subregion macrophage determinants

The effect of specific anti-I-J reagents on macrophage-T cell interactions was studied in an in vitro antibody response to burro erythrocytes. Macrophages were prepared from the spleens of F1 hybrid mice whose parental strains differed at the I-J subregion. Two F1 hybrids were used for these experiments, [B10.A(3R) X B10.A(5R)]F1 and [B10.S(9R) X B10.HTT]F1. F1 macrophages responded equally well with F1 T-B cells or with T-B cells of either parental strain. When F1 macrophages were pretreated with anti-I-J serum (without complement) specific for one parental haplotype, they were only able to cooperate with T helper (TH) cells of the unblocked haplotype and with F1 TH cells. Identical results were obtained with (Jb X Jk)F1 and (Js X Jk)F1 mice. The results indicate that TH cells possess genetically restricted receptors for macrophage I-J-subregion gene products and that the interaction between this receptor and the macrophage I-J-subregion determinants is essential for the initiation of a primary in vitro antibody response to an erythrocyte antigen.

Humoral and cell-mediated immune responses in fully allogeneic bone marrow chimera in mice

AKR mice were protected from lethal irradiation and established as long-lived chimeras by transplanting allogeneic C57BL/6 (B6) bone marrow that had been treated in vitro with anti-Thy-1 antiserum without complement. In these chimeras, which were designated [B6 {arrow} AKR], virtually all the thymus and spleen cells were shown to be derived from the B6 donor; several immune functions studied in these chimeras were as follows: (a) The chimeric mice were tolerant of histocompatibility antigens of both donor and recipient strain and nearly fully reactive to antigens of third party, as revealed by Simonsen's splenomegaly assay. The tolerance of these chimeras could not be attributed to suppressor cells but was compatible with clonal depletion. (b) Proliferative responses to concanavalin A, phytohemagglutinin, and lipopolysaccharide as well as natural killer and antibody-dependent cell- mediated cytotoxicity activity of the chimeric mice was normal. (c) Plaque- forming cell (PFC) assays of antibody responses to sheep erythrocytes (SRBC) showed gross deficiency in the primary response of the [B6 {arrow} AKR] and [AKR {arrow} B6] chimeras. By contrast, [B6-H-2(k)(E(k)) {arrow} AKR] H-2-compatible chimeras and [AKR {arrow} AKR] syngeneic marrow transplanted mice had normal primary PFC responses. PFC responses after secondary stimulation with SRBC, however, revealed vigorous direct plaque formation and substantial but somewhat smaller indirect plaque formation in the [B6 {arrow} AKR] chimeras. This observation favors operationally the concept of adaptive differentiation proposed by Katz et al. (44). (d) Analysis of ability of the chimeras to develop and express delayed-type hypersensitivity responses to contact sensitizer (2,4-dinitro-l-fluorobenzene [DNFB]) showed no apparent immunodeficiency of either chimeras to this form of immunization. Development of immunologic tolerance to DNFB, however, was grossly deficient in [B6 {arrow} AKR] chimeras but normal in [AKR {arrow} AKR], [B6 {arrow} B6], and [E(k) {arrow} AKR] chimeras. These findings indicate that full chimeras across major histocompatibility complex have considerable immunologic vigor even though primary immune responses that require histocompatibility between interacting cell types are initially defective.

Comparison of antigen-specific I-region-associated cell interaction factors

Two basic types of factors reacting with anti-I region (anti-Ia) antisera are compared, those derived from macrophage-like antigen presenting cells and others derived from T-lymphocytes, of either the suppressor or helper type. Despite the common property of reacting with anti-Ia antisera, the two sets of factors differ by many criteria. Macrophages, upon culture with antigen, release complexes of Ia antigen and a fragment of the original immunogen. This material is only produced by responder macrophages and thus appears to be a soluble Ir gene product. The genetic restriction of the T-macrophage interaction was investigated in chimeras, and it was found that the host environment as well as the donor genotype was of importance in determining restrictions, which were thus not really directed to "self." There was no evidence for intrinsic T-cell Ir genes, as nonresponder stem cells developed into responder T-cells in a (responder X nonresponder) F1 environment. However, these cells only responded in the presence of responder macrophages. Specific T-cell factors are different in nature. These all react with anti-Ia antisera, but the nature or function of the T-cell Ia is unknown. The basic structure involves a VARIAble region" responsible for antigen binding which, as it reacts with anti-idiotype antisera and anti-variable region framework antisera is an immunoglobulin variable region. There is also a "constant region," defined by its biological properties as well as by specific rabbit antisera. This two-region nature of specific factors is reminiscent of immunoglobulin structure and it is a reasonable hypothesis that the constant region is linked to the Ig cluster of genes.

Serological analysis of antigen-specific helper factors specific for poly-L(Tyr, Glu)-poly-DLAla--poly-LLys [(T, G)-A--L] and L Glu60-LAla30-LTyr10 (GAT)

In vitro prepared antigen-specific helper factors reactive to the synthetic polypeptide antigens poly-L(Tyr, Glu)-poly-DLAla--poly-LLys [(T, G)-A--L] or LGlu60-LAla30-LTyr10 (GAT) and bearing Ia determinants were analyzed serologically to determine the nature of the Ia determinants they expressed. I subregion-specific mouse anti-Ia antisera were used, and showed that (T, G)-A--L-specific helper factor (HF) contains I-A subregion-controlled determinants, whereas GAT-specific HF carries I-J subregion-controlled antigens. This unexptected finding was confirmed in both the H-2k and H-2 b haplotypes, using a variety of anti-I-J antisera. Rabbit anti-Ia antisera also reacted with both HF which raised the possibility that the Ia determinants on HF may be carbohydrate in nature. The fact that HF has a low molecular weight and yet contains Ia determinants, antigen-binding capacity and idiotypic markers is compatible with this interpretation.