Lymphocyte transformation induced by autologous cells. II. Stimulation by mitogen-induced lymphoblasts

Self-reactive delayed type hypersensitivity induced in mice by syngeneic lymphoblasts. III. Immunological characterization of the small and large antigens of the blast cells

X-irradiated or normal A mice injected with syngeneic concanavalin A-induced lymphoblasts (syn-Con A blasts) developed inflammatory responses in their footpads 24 to 72 h after the injection of syngeneic lipopolysaccharide-induced lymphoblasts (syn-LPS blasts) into these tissues. This response was designated syngeneic delayed type hypersensitivity (syn-DTH). The Con A blast extracts contain small (apparent MW of 6000-7000) and large (apparent MW of 160,000-175,000) syn-DTH-stimulating antigens, which are found in the total volume (low molecular weight fraction) and the void volume (high molecular weight fraction), respectively, of AcA 44 gel filtrations of this extract. The small and large antigens exhibit different immunological properties. The small antigen of A mouse lymphoblasts induced syn-DTH in X-irradiated (250 rad) mice but not in normal mice, and this immunological activity was elicited with syngeneic but not allogeneic lymphoblasts. The syn-DTH induced with the small antigen was inhibited by Lyt-1+2+, I-Jk+ suppressor T cells or a factor extracted from these cells. In contrast to the small antigen, the large antigen of A mouse lymphoblasts induced syn-DTH in both normal and X-irradiated mice, and this immunological activity was elicited by both syngeneic and allogeneic LPS lymphoblasts. The small and large antigens do not immunologically cross-react, but their immunogenicity is not affected by ultraviolet irradiation, indicating that the immune response against both of them is relatively class II-independent. The possibility that the cellular autoanti-lymphoblast response observed in our studies is in fact a mechanism that down-regulates the lymphoblast activity and thus suppresses the immune response is discussed.

Self-reactive delayed type hypersensitivity induced in mice by syngeneic lymphoblasts. II. Isolation of two distinct lymphoblast antigens, one of which reacts (or cross-reacts) with anti-H-2Dd monoclonal antibody

X-irradiated (250 rad) or normal A mice injected with syngeneic concanavalin A-induced lymphoblasts (syn-Con A blasts) developed an inflammatory response in their footpads 24 to 72 h after injection of syngeneic lipopolysaccharide-induced lymphoblasts (syn-LPS blasts) into these tissues. This immunological activity was designated syngeneic delayed type hypersensitivity (syn-DTH), because T cells transferred the response to naive recipients. Analysis on Ultrogel or Sephadex G-50 columns revealed that a Con A-blast extract contains two syn-DTH-stimulating antigens: a small antigen (6000-7000) and a large antigen (apparent MW of 160,000-175,000). This conclusion held true even when protease inhibitors were included in the fractionation procedure. The approximate molecular weights of these antigens estimated by the gel filtrations were confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The large lymphoblast syn-DTH-stimulating antigen contains carbohydrate residues but not products of the H-2 genetic region. The small antigen does not contain sugar moieties, but it expresses affinity to anti-H-2Dd monoclonal antibody. The immune response to the small antigen but not to the large antigen is genetically restricted at both the induction and the elicitation phases of the DTH. A strain of mice immunized with the small antigen generated syn-DTH after challenge with lymphoblasts of B10.T (6R) mice, which share the H-2Dd subregion with A mice but not the H-2K or the H-2I subregions. Fast protein liquid chromatography of the small antigen yielded a purified material which appeared as a single band after Coomassie staining of its gel electrophoresis.

On the immune reaction to autologous human lymphoblasts: evidence for the stimulation by activating factors rather than induction by autoantigens

This report questions the nature of stimulation in the lymphoblast-induced autologous mixed leukocyte reaction (AMLR). Using immobilized phytohemagglutinin (PHA) and pokeweed mitogen (PWM), we show that the AMLR generated with PHA lymphoblasts (PHA X AMLR) was not significantly different from the AMLR generated with untreated stimulators. The PWM lymphoblasts of 15 out of 33 apparently normal blood donors generated an AMLR (PWM X AMLR) greater than their respective normal AMLR. The positive PWM X AMLR was not related to the expression of HLA-DR or surface IgM, since expression of both was increased by both PHA and PWM, yet only PWM blasts stimulated in the AMLR. Fixation of PWM-stimulated cells prior to the AMLR completely abolished stimulatory capacity, indicating further against new or increased antigen expression. Inactivation by uv irradiation of surface HLA-D on the stimulators had no effect upon the PWM X AMLR, while intact protein synthesis was required in order to stimulate. The ability of cells to stimulate was associated with the release of soluble helper factors capable of stimulating autologous cells independently. These factors were neither contaminating PWM nor secreted IL-1 or IL-2, although IL-1-like activity was released by all cells regardless of their ability to stimulate. The individual variation in the PWM X AMLR response and secretion of helper factors is discussed in relation to B-cell hyperproliferation and altered immunoglobulin production in autoimmune manifestations.

Staphylococcal protein A primed leukocytes enhance the autologous mixed lymphocyte reaction

Human peripheral blood mononuclear cells (PBMC) were preincubated for 3 days in medium alone or with various mitogens then washed and irradiated. The preincubated cells then were cultured with autologous T-cells in an autologous mixed lymphocyte reaction (AMLR). Staphylococcal protein A (SPA) pretreatment of PBMC enhanced autologous T-lymphocyte proliferation from 1375 +/- 321 cpm (mean +/- SEM untreated PBMC) to 42,467 +/- 7,985 cpm (SPA primed PBMC) (p less than 0.01). The ability of SPA treated PBMC to enhance the AMLR was not simply a reflection of their proliferation in preculture, as PBMC precultured with phytohemagglutinin and concanavalin A showed greater proliferation than SPA-treated PBMC yet only minimally enhanced the AMLR. Kinetic studies and pre-exposure of PBMC to graded doses of gamma radiation showed that SPA augmentation of the AMLR was mediated by 2 components which differed in kinetics and radiosensitivity. Although incubation of PBMC with SPA did not increase the percentage of cells with detectable surface Ia antigen, SPA did increase the density of Ia in the preincubated cells. Cell separation studies revealed that SPA enhancement of the AMLR was not mediated by T-cells, but was mediated by a non-adherent non-E-rosetting fraction of cells. SPA enhancement of the AMLR was associated with an increased Ia density in the stimulator population but not with an increase in Ia positive cells and was mediated by proliferation-dependent and proliferation-independent mechanisms.

Lymphocyte proliferation induced by autologous cells. XV. Relationships between the human autologous mixed lymphocyte reaction stimulated by non-T and activated T cells

The human (T:T act) AMLR was characterized in its relationship to the (T:Non-T) AMLR and its validity as a nonxenogeneic antigen induced response was extended. Human T cell lines, established from responding T cells in an autologous mixed lymphocyte reaction (MLR), were maintained in medium containing human serum and interleukin-2 (IL-2). These cells stimulated 3H-thymidine incorporation by autologous T cells and by autologous unfractionated blood mononuclear cells. Freshly activated T cells isolated from an autologous MLR stimulated autologous T cells to a lesser extent could be enhanced by adding IL-2. Twenty-five to 50% of T cells stimulated by activated T cells express the T8 determinant. In contrast, we have previously shown that less than 10% of T cells activated after 6 days in culture with non-T cells express the T8 determinant. The number of T8 bearing cells were increased significantly after 10 days in culture with non-T cells. This suggested that two types of reactions, the (T:Non-T) and (T:T act) AMLR, might occur in sequence when T cells and autologous non-T cells are cocultured: first, the activation of T4 cells by non-T cells, then by the activation of T8 cells by activated T4 cells. Finally, activated T cells can stimulate unfractionated autologous mononuclear cells without prior exposure to sheep erythrocytes or fetal calf serum.

The effect of cyclosporin on murine autoreactive delayed type hypersensitivity induced with syngeneic lymphoblasts

The effect of cyclosporin on an immunological autoreactive experimental model was analyzed. The experimental system consisted of X-irradiated A mice injected with syngeneic concanavalin A-induced lymphoblasts and footpad-challenged 7 days later with syngeneic lipopolysaccharide-induced lymphoblasts. 24-72 h after challenge, the footpads of these mice responded with significant swelling, accumulation of 125I-UdR or massive cellular infiltration revealed by histological examination. Since the immunological activity was transferred by Lyt-1+ T cells from the sensitized donors to naive recipients, we designated it 'syngeneic delayed-type hypersensitivity' (syn-DTH). This DTH was induced and elicited mostly by antigens of the syngeneic lymphoblasts and not by contaminants attached to them, indicating the immunological autoreactive nature of this system. Multiple doses of 60 mg/kg cyclosporin, given daily in the time interval between immunization and challenge, or on the last four days before challenge, inhibited the syn-DTH. Multiple injections of cyclosporin Before or close to the induction phase of the syn-DTH was ineffective, whereas single or multiple injections of cyclosporin close to the effector phase (the challenge time) markedly reduced the syn-DTH. Even a single injection of cyclosporin 24 h after the challenge efficiently reduced the 48-h syn-DTH. Adoptive transfer experiments revealed that T cells from X-irradiated mice immunized with concanavalin A-induced lymphoblasts and injected with cyclosporin, failed to efficiently transfer the syn-DTH response to naive recipients. Similarly, the syn-DTH response of naive X-irradiated recipient mice injected with cyclosporin, failed to be reconstituted with primed T cells derived from X-irradiated mice immunized with concanavalin A-induced lymphoblasts. Since the nonspecific footpad swelling response of X-irradiated mice challenged with lymphoblasts alone is resistant to the standard protocol of the cyclosporin treatment, we suggest that cyclosporin inhibits the ability of T cells to produce or release lymphokines at the effector phase of DTH, while phagocytic cells involved in the DTH response are not affected by it. The practical and the theoretical implications of this research are discussed.

High and low density PHA- (but not ConA-) activated T cells stimulate the autologous mixed lymphocyte reaction

In this study, PHA- and ConA-activated cells (PAC and CAC) were used as stimulators in mixed lymphocyte reactions (MLR) using autologous (auto) and allogeneic (allo) peripheral mononuclear cells as responders. PAC, but not CAC, were stimulatory in allo- and auto-MLR, and this stimulation was not due to residual PHA. In PAC which have been activated for 96 h, auto-MLR was due to determinants present on low density T-cell blasts, while with PAC which had been stimulated for more than 192 h, the determinants seemed to be associated with high density T cells. Anti-T3 monoclonal antibodies and certain anti-DR suppressed auto- and allo-MLR mediated by PAC when present throughout the entire MLR assays. CAC suppressed PAC-mediated auto-MLR in a dose-dependent fashion. This inhibition was not DR-restricted and was reversed by the addition of exogenous IL-2. Our results indicate that: depending upon the length of activation, both low density and high density PHA-activated T cells exhibited strong stimulatory capacity in auto-MLR; ConA-activated T cells failed to stimulate auto- or allo-MLR and suppressed MLR mediated by PAC; this suppression was due to suppressor cells, not to suppressor factors, and was readily reversed by exogenous IL-2; pretreatment of CAC with anti-TAC did not reverse the inhibition.

Self reactive delayed type hypersensitivity (DTH) induced in mice by syngeneic lymphoblasts

Normal and x-irradiated A mice injected with syngeneic concanavalin A (Con A)-induced lymphoblasts revealed after challenge with syngeneic lipopolysaccharide (LPS)-induced lymphoblasts delayed type hypersensitivity (DTH) measured both by footpad swelling and by 125IudR accumulation. Mice injected with allogeneic Con A-induced lymphoblasts and challenged with syngeneic LPS-induced lymphoblasts or vice versa, also generated an appreciable DTH response. In contrast, Con A-induced blast cells of human origin (xenogeneic cells) generated a considerably less effective DTH. The DTH response was more profound and consistent in x-irradiated mice, suggesting that irradiation sensitive cells control this response. The syngeneic DTH response was efficiently transferred to naive recipients with Thy-1+, nylon wool passed cells. The establishment of the DTH activity was associated with the lymphoblasts own (differentiation?) antigens and not with contaminants attached to the cells, such as Con A or fetal calf serum. The results were compared with similar results reported by other groups and the biological significance of all findings was evaluated.

Activated B lymphocytes: stimulators of an augmented autologous mixed leukocyte reaction

The characteristics of the non-T cell(s) which stimulate T-lymphocyte proliferation in the autologous mixed leukocyte reaction (AMLR) have been at issue since this in vitro reaction was first described. Dendritic cells have been shown to be the most potent stimulator cells, but B cells, null cells, and macrophages have also been demonstrated to have the capacity to stimulate autologous T-cell proliferation. A cell preparation obtained from human peripheral blood was highly enriched for surface immunoglobulin-positive B cells. These cells were activated by brief culture with various B-cell mitogens and then compared to untreated B cells with regard to stimulatory activity in the AMLR. Mitogen-activated B cells were markedly augmented in their capacity to stimulate autologous T-cell proliferation when compared with untreated B cells. Fractionation of the B-cell preparation into high- and low-density subpopulations demonstrated that the high-density cells, enriched in resting B cells, had minimal stimulatory activity but could be activated to have increased AMLR-stimulatory capacity. Proliferation of the activated B lymphocytes was not required for the generation of the augmented AMLR. Response to both untreated and mitogen-activated B cells was a property of T4-positive T lymphocytes. The increase in stimulatory capacity was associated with a decrease in cell surface immunoglobulin, but no significant alteration in the percentage or fluorescence intensity of anti-Ia staining cells was detected. Activated B cells which are generated in vivo may acquire the capacity to generate T effector cells or factors important in the regulation of B-cell function.

Lymphoblastogenesis stimulates proliferation of interacting Lyt1 T cells in a syngeneic system

The intravenous transfer of polyclonally activated lymphoblasts elicited a proliferative response of host-derived Lyt1 T cells in the spleens of syngeneic recipient mice. These Lyt1 T cells (responding in vivo to a syngeneic lymphoblast graft) stimulated proliferation of resting, syngeneic splenic Lyt1 T cells, derived from uninjected mice, in a one-way syngeneic mixed lymphocyte culture in vitro. The data are discussed in the context of T cell activation induced by lymphoblastogenesis in a syngeneic system.

"Self-reactive" T cells. II. Transferred syngeneic lymphoblasts induce T "stimulator" cells in vivo, to which syngeneic T cells "respond" in a syngeneic MLC in vitro

Splenic T cells, engaged in an in-vivo "response" to transferred syngeneic lymphoblasts, displayed an extensive proliferative activity if cultured in vitro. These cells (blocked by mitomycin C) were "stimulator" cells in a one-way syngeneic mixed lymphocyte culture (S-MLC). "Responder" cells were derived form spleens of syngeneic (sex and age matched) mice. Fractionation studies showed that "stimulator" and "responder" cells in the investigated S-MLC were nylon-wool non-adherent and sensitive to treatment with anti-Thy-1 antiserum and complement, i.e. were cells of the T lineage. Coculture experiments demonstrated that direct cell contact is required to trigger a proliferative "response" in the S-MLC. Fetal calf serum-supplemented tissue-culture medium supported "responder" cell proliferation, normal mouse serum-supplemented medium did not. The in-vivo generation of a T-cell population, which could "stimulate" a syngeneic T-cell "response" in the S-MLC in vitro, was investigated.

"Self-reactive" T cells. I. In vivo reaction of T cells to transferred polyclonally activated syngeneic and autologous lymphoblasts

Polyclonally activated splenic lymphocytes (generated in mitogen-stimulated cultures) were transferred to syngeneic or autologous recipient mice. Injection of cells into the footpad of syngeneic recipients induced a regional response in the ipsilateral popliteal lymph node; intravenous cell transfer elicited a systemic splenomegaly reaction. These reactions displayed a linear log number of transferred cells/response relationship in syngeneic and autologous systems. The kinetic and magnitude of the regional response to syngeneic lymphoblasts ands to allogeneic spleen cells were comparable. No difference was apparent in the phenomenology of the in-vivo responses to syngeneic lymphoblasts induced by various T- or B-cell mitogens. The in-vivo response was: 1. stimulated by large-size lymphoblasts; and 2. mediated by host T cells. Data excluded a direct involvement of mitogen or heterologous serum constituents in tissue culture medium in the described reaction. Experimental evidence argues against the involvement of virus components in the observed phenomenon.

Cellular interactions in spontaneous or autologous cell-induced proliferative and lymphokine responses of human lymphocytes

Purified human B cells were activated in cultures in the absence of any intentional stimulants as judged by lymphokine synthesis and proliferation. These responses were not augmented by monocytes. Lymphokine production (LIF) was increased in the presence of T cells. Autologous mixed lymphocyte reaction of T cells against B cells (AMLR) did not include LIF production in spite of the proliferative response. We would suggest that activated B cells present in the population of purified B cells are the stimulators in AMLR. In our interpretation these results support the hypothesis that AMLR reflects a mechanism by which T cells regulate lymphocyte function.

Suppressor cells induced by purified protein derivative of tuberculin (PPD): the suppression is mediated by cells that proliferate in response to stimulation with PPD

Lymphocytes stimulated with purified protein derivative of tuberculin (PPD) were found to inhibit the PPD stimulation of fresh, autologous lymphocytes. This suppressor effect was exerted after preincubation with both high and low concentrations of PPD. Optimal suppression occurred after preincubation with PPD in concentrations of 5 micrograms/ml and higher, the same concentrations that gave optimal stimulation of DNA synthetsis in primary cultures. The suppressor effect was abolished completely by 'hot pulse' treatment and partly by treatment with colchicine during PPD preincubation, showing that the PPD-induced suppressr cells are generated by cell division. When fresh lymphocytes were incubated together with PPD-pretreated cells in cultures that were not stimulated with PPD, the PPD-stimulated lymphocytes exerted a stimulatory effect on the fresh lymphocytes. This effect was maximal for cells preincubated for 1 h with PPD, decreasing with increasing duration of preincubation with PPD. Possible explanations of this observation are discussed.

Properties of reticulum cell sarcomas in SJL/J mice. V. Nature of reticulum cell sarcoma surface antigen which induces proliferation of normal SJL/J T cells

The results of studies on the reticulum cell sarcoma (RCS) tumors of SJL/J mice presented here, indicate that spontaneous tumors, which arise in older mice, also possess the capacity to induce the vigorous proliferative response in syngenetic T lymphocytes that are characteristic of the transplantable RCS lines. Analysis of cell surface antigens revealed the presence of Ia determinats on gradient-purified transplantable RCS tumor cells; however, these cells did not express Thy 1.2, nIg, or, any of the viral proteins that were tested for by specific antisera. Pretreatment of RCS cells with anti-Ia sera and complement-deleted cells that were stimulatory for syngenetic T lymphocytes, and addition of anti-Ia sera directly to cultures blocked the proliferative response at the stimulator (RCS) cell level. Lymph node cells from H-2(8) strains other than SJL/J, including A.SW and B10.S also gave proliferative responses to RCS cells, although lower in magnitude. A requirement on the part of responding cells for identity with RCS cells at the Ir region was indicated by the finding that A.TH but not A.TL lymph node cells responded to RCS. It is concluded that RCS cells stimulate Ir-region identical T cells (without evidence of presensitization) through a modification in the expression of Ia antigens on the surface of the tumor cells.

Lymphocyte transformation induced by autologous cells. IV. Human T-lymphocyte proliferation induced by autologous or allogeneic non-T lymphocytes

An autologous mixed lymphocyte reaction was demonstrated between T and non-T lymphocytes. Sheep erythrocyte rosetting was used to separate human lymphocytes into T and non-T lymphoid preparations. Non-T lymphocytes stimulated the proliferation of autologous T lymphocytes. The cell in this preparation that was most stimulatory had the characteristics of a K lymphocyte. The allogeneic mixed lymphocyte reaction was also shown to reflect the proliferation of T lymphocytes stimulated by allogeneic non-T lymphocytes. Proliferation of T lymphocytes in the allogeneic mixed lymphocyte culture probably reflects a response to both foreign histocompatibility determinants and determinants present on non-T lymphocytes. It is suggested that the proliferative response of T lymphocytes to autologous non-T lymphocytes may be a step in the process by which T lymphocytes regulate immunity.

Response of remission lymphocytes to autochthonous leukaemic myeloblasts

Thymidine incorporation in vitro by remission lymphocytes from a total of 6 patients with acute myeloid leukaemia (AML) was measured following stimulation by autochthonous and allogeneic AML blasts and cell lines. The early peak response to autochthonous blasts in 2 of these patients (48-72 h) is consistent with the concept of a population of lymphocytes pre-immunized to antigens carried by the blasts. Although stimulation in one patient was increased in the presence of more stimulating (S) blasts than responding (R) lymphocytes, positive responses in other tests were obtained at an S : R ratio of 1 : 1-5. When different methods of treatment of the stimulating autochthonous blasts were compared with untreated cells, mitomycin C gave the highest stimulation indices 2 out of 3 tests. Tissue culture medium in which autochthonous blasts had been incubated for 3-5 days failed to stimulate either remission lymphocytes alone, or combined cultures of lymphocytes with autochthonous or allogeneic blasts, suggesting that mitogenic factors released from autochthonous blasts are not responsible for lymphocyte stimulation. Treatment of autochthonous or allogeneic AML blasts with glycine-HC1(pH 3-0) to remove putative "blocking" factors failed to increase the stimulatory capacity of the leukaemic blasts.

Properties of reticulum-cell sarcomas in SJL/J mice. I. Proliferative response to tumor cells of T-derived lymphoid cells from normal mice

Cells from reticulum-cell sarcomas (RCS), tumors with a probable B-cell origin in the SJL/J mouse strain, induced a high degree of proliferation in O-bearing syngeneic lymph-node and thymus cells obtained from young non-tumours mice. Although of considerably lower magnitude, a proliferation of SJL/J thymus cells to syngeneic normal lymph-node cells was also noted. Sera from normal syngeneic mice did not block either of these proliferative responses. Stimulation by RCS cells also occurred with normal lymph-node cells from F1 hybrids, SJL/J times C57Bl/6, and SJL/J times ASW and from the H-2s identical ASW mouse strain. It is suggested that these results are due either to the presence of viral antigens on the surface of RCS cells or to an exaggerated form of the normal syngeneic response of T to B lymphocytes. Another tumor of B-cell origin, the PU5 tumor of BALB/c mice, failed to induce proliferation in normal syngeneic lymph-node or thymus cells.