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

Role of Ia antigens in the human autologous mixed lymphocyte reaction

The role of Ia antigens in the human autologous mixed lymphocyte reaction (MLR) was analyzed. To do this, different mononuclear cell populations were fractionated according to their Ia antigen expression and used as stimulating cells in autologous MLR. Also examined was the effect of two hybridoma monoclonal antibodies specific for human Ia molecules on the autologous MLR. The results show that the stimulating capacity of peripheral blood mononuclear cells is restricted to Ia-bearing cells. While peripheral blood T cells are unable to function as stimulating cells, highly purified Ia+ mixed lymphocyte culture-activated T cells are very effective. The possibility that Ia molecules are directly involved in the autologous MLR is further substantiated by the strong inhibitory effect of monoclonal anti-Ia antibodies.

Stimulation of human T lymphocytes by PHA-activated autologous T lymphocytes: analysis of the role of Ia-like antigens with monoclonal antibodies

Human T lymphocytes activated with PHA express Ia-like antigens and acquire the ability to stimulate autologous T lymphocytes in mixed lymphocyte reaction. This reaction is immunological in nature since it has specificity and memory. Ia-like antigens play a role in the stimulation of T lymphocytes by autologous PHA-T lymphocytes since monoclonal antibodies to Ia-like antigens can significantly, although not completely, inhibit the stimulation.

Adherent Ia+ murine tumor lines with characteristics of dendritic cells. I. Morphology, surface phenotype, and induction of syngeneic mixed lymphocyte reactions

Several adherent cell lines that express surface Ia antigens have been cloned from the P388 leukemia. These cell lines express many morphological and functional similarities to dendritic cells of the spleen. Adherent clones express H-2 gene products from the I and D regions, but do not possess Fc or C3b receptors or surface Ig. The cytoplasm of the adherent P388 clones has an abundance of mitochondria but few phagolysosomes. The adherent clones all strongly stimulate the proliferation of syngeneic or allogeneic T lymphocytes in the absence of antigen; however, cytotoxic T cells directed against the stimulators are induced only during allogeneic stimulation. Nonadherent clones of P388, which also express Ia antigens, do not stimulate either allogeneic or syngeneic T cell proliferation. The isolation of Ia-bearing adherent cell lines makes it possible to study Ia-mediated events in both antigen-dependent and independent immune systems using homogeneous accessory cell populations.

Responder cells in the human autologous mixed lymphocyte reaction

Isolated human T4+ cells proliferate in the autologous mixed lymphocyte reaction (AMLR), whereas isolated T8+ cells do not. However, in the presence of Interleukin 2 or T4+ cells, the T8+ cells demonstrated substantial proliferation. These studies suggest that T8+ cells recognize signals from autologous non-T cells, but require an additional factor for the subsequent proliferative response. Since this stimulus can be provided by T4+ cells, the AMLR appears to constitute an inducer circuit. Different defects in this circuit may be responsible for the common abnormality of the AMLR in different diseases.

The suppressive effects of monocytes in the autologous mixed lymphocyte reaction

The response of isolated T cells to autologous non-T mononuclear cells is called the autologous mixed lymphocyte reaction (AMLR). The responding T cells show immunological memory and specificity. This reaction was present in all thirty normal individuals tested. Since the AMLR in the absence of evidence of in vivo excessive lymphoproliferation must somehow be controlled, we have studied the interactions of enriched T cells, B cells and monocytes in culture as possible means of regulation of this reaction. Increased rate of [3H] thymidine incorporation by T lymphocytes were observed when they were cultured with mitomycin-treated autologous non-T cells. This was increased when the stimulating cells were enriched for B lymphocytes and was significantly decreased when the stimulating cells were enriched for monocytes. Addition of monocyte-enriched cells to B-enriched cells in a 1:1 ratio, significantly suppressed the AMLR (P- less than 0.01). Equivalent numbers of monocytes did not suppress T-cell responses to phytohaemagglutinin (PHA). Monocyte-enriched cells were separated from stimulating B-enriched cells by nucleopore (0.6 mu) or dialysis tubing (0.12 mu) in Marbrook chambers. Soluble products released from monocyte-enriched cells also suppressed the AMLR. The significance of the AMLR in vivo is uncertain but it may be important in immunoregulation, monocytes playing an important role.

An alpha2-macroglobulin associated factor produced by T lymphocytes which provides polyclonal stimulation of B lymphocytes to maintain the turnover of their surface Ig

The supernatant of 'crowded' but not 'spread' rabbit spleen cell cultures contains a macroglobulin factor which behaves in an Ig-turnover assay as any T-independent antigen or polyclonal B-cell activator (PBA). In the supernatants of crowded rabbit lymphoid cell cultures prepared in serum free medium, the factor was found to be associated entirely with the alpha-macroglobulin (alpha M) fraction (alpha 1 + alpha 2). This alpha M was most probably actively secreted by the lymphocytes because: (i) sequential supernatants obtained in serum free medium of crowded cultures contained equal amounts of alpha M as well as equal PBA activity; (ii) the alpha M became labelled when the cells were grown in medium containing a radioactive amino acid. Macrophages were not required for the production of PBA. PBA was not produced when either crowded B or T cells were cultured alone but only when they were cultured together. Purified T cells were not triggered by any plant lectin to produce PBA. By use of anti-alpha 2M allotype antibodies and B and T cells from different rabbits, the PBA was shown to have the allotype of the T-cell donor. The PBA was associated with rabbit alpha 2M but not alpha 1M. We concluded that upon close contact, B cells stimulate T cells to produce a PBA associated with alpha 2M.

Factors influencing the autologous mixed lymphocyte reaction in rats: effect of xenogeneic serum protein

Mixed culture of nylon non-adherent (T-enriched) spleen cells or lymph node cells of ACI/N or F344 rats with mitomycin C-treated autologous spleen cells resulted in the increased DNA synthesis of the responder T cells when they were cultured in medium containing foetal calf serum (FCS) or bovine serum albumin. This autologous mixed lymphocyte reaction (AMLR), however, proceeds little when the cells were cultured in medium containing autologous or allogeneic rat serum, irrespective of the responder:stimulator cell ratio and to the culture period. Furthermore, the AMLR response in FCS was greatly reduced if a relatively large number of macrophages were present in the responder cell population. These results suggest that the AMLR response is unlikely to occur in a physiological condition or in vivo.

Murine syngeneic mixed lymphocyte response. I. Target antigens are self Ia molecules

A system has been described that produces a murine syngeneic mixed lymphocyte response (MLR) comparable in magnitude to an allogeneic MLR. The responder cells in these cultures exhibit the classic immunologic characteristics of both memory and specificity. Studies using radiation-induced bone marrow chimeras of F(1) {arrow} parent type indicated that, similar to many other T cell-mediated immune responses, the response of the T lymphocytes in the syngeneic MLR was major histocompatibility complex-restricted and was determined by the environment in which the T cells matured. Using responder T cells from F(1) {arrow} parent chimeras and stimulator cells from H-2 recombinant strains, it was possible to map the genes involved in the stimulation to the K and/or I regions. In addition, blocking studies with monoclonal anti-Ia antibodies suggested that in the B10.A strain the critical molecules were products of both the I-A(k) and I-E(k) subregions. The issue of whether the syngeneic MLR is directed solely at self I-region antigens or whether the response represents proliferation to an unknown antigen in association with self I-region determinants was also addressed. Secondary syngeneic MLR were successfully performed in normal mouse serum and with stimulator cells prepared in the absence of bovine serum albumin to rule out the possibility that xenogeneic serum antigens were involved in the stimulation. The possibility that the syngeneic MLR might represent a secondary response to environmental antigens was eliminated by using germ- free mice as a source of stimulator cells and by demonstrating that spleen cells from unimmunized, fully allogeneic chimeras (B10.A {arrow} B10) could generate a normal syngeneic MLR even though such chimeras could not be primed to respond to any foreign antigens unless supplemented in vivo with a source of antigen-presenting cells syngeneic to the B10 host. The possibility that the syngeneic MLR was a primary response to a foreign antigen was considered unlikely because by using our culture conditions we could not obtain a primary antigen response or a secondary antigen response after in vitro priming to a variety of potent foreign antigens. Finally, the possibility that the syngeneic MLR represents a response to a variety of minor histocompatibility self antigens in association with self Ia molecules was eliminated by showing that the secondary responses to H-2 compatible, non-H-2 different strain (A/J vs. B10.A and C3H, or BALB/c vs. B10.D2 and DBA/2) were comparable to the secondary responses to syngeneic stimulators. Thus, we conclude that the target antigens in the syngeneic MLR are solely determinants on self Ia molecules, although the functionally equivalent possibility of a single, nonpolymorphic, minor self antigen seen in association with self Ia molecules cannot be excluded.

Generation of suppressor cells in the autologous mixed lymphocyte reaction

When challenged with HLA-A, B and DR incompatible cells, T cells which have been primed in an autologous mixed lymphocyte response (AMLR) show an accelerated (day 2) component of their proliferative response, as well as the expected primary-style response at day 5. This early response of AMLR-primed cells to allogeneic stimulation, like the response to rechallenge with autologous cells, is abolished by treatment of the primary culture with BUdR and light. These results suggest that priming in the AMLR is not solely to MHC-private specificities, and that an antigenic element common to autologous and allogeneic cells is recognized. The AMLR also generates cells with suppressor activities. AMLR-primed cells suppress the proliferative responses of fresh T cells from the same donor to autologous or allogeneic stimulation. Limiting numbers of suppressor cells are more effective suppressors of the autologous, than of the allogeneic response. Suppressor activity is reduced but not abolished by treatment with mitomycin C. AMLR-primed cells also suppress pokeweed mitogen-induced antibody production by fresh peripheral blood lymphocytes. In some experiments, specific antigen-induced antibody production is also suppressed.

In vitro synthesis of IgE by human peripheral blood leucocytes. II modulation of IgE B cell activity by isotype-specific regulatory T cells

IgE and IgG synthesis was demonstrated in cultures of isolated B cells from normal subjects, and those manifesting mild to severe atopy. Titration of autochthonous T cells into B cell cultures revealed both IgE isotype-specific T-help and T-suppression at low and high T:B ratios respectively. Increasing levels of help for IgG synthesis usually accompanied the stepwise addition of the same T cells to autochthonous or allogeneic B cells cultures. Experiments comparing the activity of putative IgE suppressor T cells in autochthonous versus allogeneic B cell cultures indicated that allogeneic interactions per se selectively inhibit IgE B cells. This finding seriously questions earlier conclusions of a causal relationship between suppressor cell deficiency and the expression of the allergic phenotype.

Autologous rosette-forming T cells regulate responses of T cells. Phenotypic and functional analysis of suppressor cells generated from autologous rosette-forming T cells after autologous mixed lymphocyte reactions

An average of 5--9% of human peripheral blood of T lymphocytes from rosettes with autologous erythrocytes (ARFT). This population responded only slightly against autologous and allogeneic non-T cells. In contrast, T cells that did not form rosettes with autologous erythrocytes (NRFT) proliferated to a greater degree in auto- and allogeneic mixed lymphocyte reactions (MLR) and also in reactions to trinitrophenyl (TNP) modified autologous non-T cells (TNP-auto-MLR) as compared with ARFT or unfractionated T cells. The ARFT populations could suppress the increased allogeneic (allo)MLR and TNP-auto-MLR of NRFT when the ARFT were added to the NRFT at the beginning of the cultures. Fluorescence-activated cell-sorter (FACS) analysis of these freshly obtained T cell fractions using monoclonal antibodies to subpopulations of T cells did not demonstrate any selective gain or less of T cell subsets in the ARFT and NRFT as compared with unfractionated T cells. But when each T cell fraction was cultured separately for a week in the presence of autologous non-T cells (auto-MLR) and the cells were again analyzed by fluorescence-activated cell sorter, there was an increase in OKT8-positive cells (suppressor/cytotoxic subset) only in the ARFT fraction. The above findings strongly suggest that suppressor T cells are generated from the ARFT fraction during an auto-MLR, these may then regulate the responses on NRFT.

Reactivity to autologous non-T-cells and suppressor function of human autologous rosettes

A subset of human peripheral blood T-cells can form rosettes with autologous erythrocytes (autologous rosettes). Fractionation of T-cells by autologous rosette centrifugation demonstrated that the autologous rosettes, but not the non-rosetting cells, have the capacity to respond with increased DNA synthesis to autologous non-T-cells in the autologous mixed lymphocyte reaction (MLR) and to suppress the mitogenic response after activation with concanavalin A (Con A). Furthermore, the autologous rosettes, autologous MLR and Con A-induced suppressor activity were particularly enriched in the nylon wool non-adherent T-cells and depleted in the nylon wool adherent T-cells. These results suggest that the same or at least largely overlapping T-cell subsets are responsible for the autologous rosettes, autologous MLR and Con A-induced suppressor function.

Monoclonal antibody analysis of human T lymphocyte subpopulations exhibiting autologous mixed lymphocyte reaction

In autologous mixed lymphocyte reaction (MLR), T cells proliferate in response to the stimulation by autologous non-T cells. In the present study, human T cell subpopulations, defined by murine monoclonal antibodies OKT4, OKT8, or 9.3, were examined for their capacity to proliferate in autologous and allogeneic MLR. It was observed that the treatment of responder T cells with OKT4 or 9.3 antibody (both defining helper/inducer T cells) and complement (C') ablated their proliferative response in autologous MLR and markedly reduced their allogeneic MLR proliferative response. In contrast, treatment of T cells with OKT8 antibody (defining suppressor/cytotoxic T cells) and C' had no or minimal effect on their proliferative response in autologous MLR. Furthermore, OKT4, 9.3, 9.6 (PAN), or 7.2 anti-human Ia (framework specific) but OKT8 antibody, when present during the entire culture period, in the absence of C' inhibited in a dose-dependent manner the proliferative response in both autologous and allogeneic MLR. Inhibition of proliferation was also observed when the responder T cells were pretreated with OKT4 or 9.3 antibody, washed, and then stimulated with irradiated autologous or allogeneic non-T cells. Pretreatment of T cells with OKT8 or 7.2 anti-Ia antibody in the absence of C' did not influence their proliferative response in autologous MLR. Thus, T cells containing cells with helper/inducer activity defined by OKT4 or 9.3 antibody appear to be the major responder T-cell subpopulation in autologous MLR.

Responses of canine lymphocytes to allogeneic and autologous Islets of Langerhans in mixed cell cultures

Because successful allotransplantation of islets of Langerhans isolated by collagenase digestion has been difficult in many animal species, we asked whether isolated islet preparations might have tissue specific determinants conferring amplified immunogenicity in vitro. Lymphocyte proliferative responses ([(3)H]thymidine uptake) were studied in beagle dogs in mixed culture combinations of lymphocyte vs. lymphocyte (MLC) and lymphocyte vs. islet (MLIC). In five MLC responder and five nonresponder pairs, peripheral blood lymphocytes of dogs A and B were used as responding cells, and dog B x-irradiated lymphocytes (Bx), x-irradiated (or nonirradiated) islets (BI), or hepatic cells (BH) were used as stimulating cells in primary and secondary reactions. For the secondary reactions, A + Bx, A + BI, or B + BI were incubated for 9 d (A'B, A'BI, B'BI, respectively) before addition of new stimulating cells. The results showed that islets were autostimulatory, eliciting a tissue-specific lymphoproliferative response in a primary MLIC. Thus, B + BI reactivity was evident at 3,5, and 7 d in primary culture, whereas collagenase-digested liver cells, or lymphocytes obtained from collagenase-digested lymph nodes did not stimulate autologous lymphocytes. A separate reactivity was observed in the allogeneic A + BI combination in MLC responder pairs, and the peak response of A + BI at 9 d was markedly greater than that of B + BI, suggesting the presence of major histocompatibility complex lymphocyte-defined locus determinants in the islet preparations, in addition to islet-specific determinants. A secondary reaction was observed if lymphocytes were primed with islets and challenged with islets (A'BI + BI or B'BI + BI), but not if they were challenged with lymphocytes (A'BI + Bx, B'BI + Bx) or hepatic cells (A'BI + BH, B'BI + AH). Furthermore, priming of lymphocytes with autologous islets (B'BI) led to exclusion of any reactivity against allogeneic lymphocytes, i.e., B'BI suppressed A + Bx, and B'BI also markedly suppressed phytohemagglutinin-stimulated lymphoproliferative responses. Experiments were performed that excluded the possibility that the insulin levels present in the MLIC, the presence of passenger lymphocytes in the islets, or the maintenance of islets in tissue culture for 1-7 d affected the observations. These results provide evidence for the existence of alloantigens as well as tissue-specific antigens on collagenase-isolated islets of Langerhans.

Autologous lymphocyte proliferation in multiple sclerosis and the effect of intravenous ACTH

The proliferative response of peripheral blood T cells to autologous non-T cells, a reaction called the autologous mixed lymphocyte reaction (MLR), was significantly increased in 17 patients with active multiple sclerosis (MS) compared to age- and sex-matched individuals with other neurological diseases (OND). Following a 10-day course of intravenous adrenocorticotropic hormone (ACTH) therapy the values were reduced to control levels. No differences were noted between MS patients and controls in their response to alloantigens. The increased autologous MLR in patients with active MS appeared to result from an increased stimulatory capacity of non-T cells rather than from an intrinsically greater T cell proliferative potential. ACTH appeared to induce a change in the populations of circulating non-T cells such that these cells had a decreased stimulatory capacity in both autologous and allogeneic MLR. The decrease in stimulatory capacity in autologous MLR was, however, significantly greater than the decrease in allogeneic stimulatory capacity, suggesting a functional decrease of specific non-T cell-enriched subpopulations. No significant changes in the numbers of myeloperoxidase-positive (MP+) cells were noted in the blood of MS patients before and after ACTH therapy. Since the autologous MLR results in generation of cells that regulate immune responsiveness, the changes noted provide additional evidence for abnormal immune regulation in MS.

Autologous mixed lymphocyte reaction in man. III. Regulation of autologous MLR by theophylline-resistant and -sensitive human T-lymphocyte subpopulations

Human peripheral blood T lymphocytes were separated into theophylline-resistant (TR) and -sensitive (TS) subpopulations. Proliferative responses TR, TS and unfractionated T cells were studied, using irradiated autologous or allogeneic non-T cells as stimulators. TR cells proliferated vigorously in both autologous and allogeneic mixed lymphocyte cultures (MLC). TS cells. which constitute about 20% of unfractionated T cells, exhibited poor proliferative responses to autologous and allogeneic stimulation. The magnitude of proliferation in autologous and in allogeneic MLC was found to be directly dependent on the number of TR cells in the culture. Mitomycin-C (MMC)-treated TR cells augmented and MMC-treated TS cells suppressed (P less than 0.05) the autologous and allogeneic MLC responses of unfractionated T cells. However, the response of TS cells did not increase in autologous or allogeneic MLC when co-cultured with MMC-treated TR cells. MMC-treated TS cells, when co-cultured with TR cells, suppressed the responses of TR cells (P less than 0.05). The enhancing effect of TR cells was radiation-resistant. Suppressor influence of TS cells, in contrast, was abolished by irradiation (P less than 0.05). These findings demonstrate that TR cells are the responding cell in autologous MLR and augment the MLC responses of unfractionated T cells. TS cells, on the other hand, respond poorly in autologous or allogeneic MLC and suppress the response of TR cells.

Evidence of aberration of T-cell subsets in aged individuals

In the present study, T-cell subsets from aged individuals were examined by using anti-BAT (brain-associated thymocyte antigen) serum. Anti-BAT serum was raised against the human fetal brain at 28 weeks of gestation. After absorption wit AB erythrocytes, B-cell lines, and leukaemic cells, anti-BAT serum was T cell-specific but unreactive to normal B cells. The ability of anit-BAT serum-treated lymphocytes from aged individuals to respond to concanavalin A, phytohaemagglutinin, and pokeweed mitogen (PWM) was unaltered even at a high concentration. In PWM-stimulated Ig synthesis, T lymphocytes lacking the anti-BAT serum-reactive T-cell subset enhanced the PWM-stimulated Ig synthesis of autologous B lymphocytes from young individuals. The Con A-induced suppressor function of lymphocytes from aged individuals was not significantly abolished by treatment with anti-BAT serum and complement. In the autologous mixed lymphocyte reaction, the decrease in response was minimal when responder cells from aged individuals was treated with anti-BAT serum even at a high concentration. It is concluded that the T-cell subset with suppressor function is defective in aged individuals.

Antigen-reactive T cells can be activated buy autologous macrophages in the absence of added antigen

T cells responsive to macrophages (M phi) in the autologous mixed lymphocyte reaction (AMLR) contain those cells that can be induced to proliferate by soluble antigens. Negative solution (5-bromo-2-deoxyuridine and light) of T cells activated by autologous M phi also removed those cells required for reactivity to Candida albicans and purified protein derivative. Positive selection of T cells responsive to autologous M phi yields a population that is simultaneously enriched in antigen reactivity. Some patients demonstrating cutaneous anergy and diminished in vitro blast transformation in response to soluble antigen also lack T cells responsive to the AMLR to M phi. When considered in conjunction with previously reported data, these findings indicate the AMLR occurring between T cells and M phi in the absence of soluble antigen represents self recognition occurring between antigen-reactive T cells and antigen-presenting M phi.

Deficiency of the autologous mixed lymphocyte reaction in patients with primary biliary cirrhosis

In this study we show that patients with primary biliary cirrhosis (PCB) have a marked deficiency in the ability to generate an autologous mixed lymphocyte reaction (AMLR) but have a normal ability to generate an allogeneic mixed lymphocyte reaction (MLR). This deficiency is not due to differences in the time-course of the proliferative response or to an altered response to variable numbers of stimulator cells. The deficiency was consistently found irrespective of the methods used to isolate autologous stimulator cells. Both responder cells and stimulator cells obtained from patients with PBC were similar to normal cells in their ability to generate an MLR in allogeneic normal human serum. In addition, serum from patients with PBC inhibited the ability of normal lymphocytes to generate both the AMLR and MLR to a similar degree, suggesting that the defect of the AMLR in PBC is not due to a serum factor. It has been shown that the responder cell population in the AMLR contains a subpopulation of cells that mediate suppression. Therefore, it is possible that the deficiency of the AMLR may be related to previously described abnormalities of suppressor function in patients with PBC.

Addition of serum to the medium used for preparation of cell suspensions as a possible source of artifacts in cell-mediated reactions studied by means of the popliteal lymph node test

Conditions for preparations of cells used in immunogenetic studies may substantially affect their properties and the results obtained. It was found that short-term incubation or a mere preparation of parental spleen cells in a medium containing either xenogeneic serum or concanavalin A (Con A) increase their ability (after footpad injection) to induce enlargement of the popliteal lymph node in (B10.LP x A/Ph)F1 hybrid recipients. Under similar conditions, enlargement of PLN could be induced also by syngenetic F1 hybrid cells. The greater lymphadenomegaly following the injection of parental or syngeneic cells prepared in serum-containing medium may be explained by the host reaction against additional foreign antigens rather than increased GVH reactivity or autoimmunity.

Lymphocyte transformation in patients with cutaneous T-cell lymphomas

The proliferative responses of peripheral blood mononuclear cells from ten patients with cutaneous T-cell lymphoma were tested after stimulation with a variety of mitogens, including phytohemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM), staphylococcal protein A (SPA), and lymphocyte-conditioned medium (LyCM). Responses were measured by the incorporation of tritiated thymidine and by flow microfluorometry (FMF). In general, responses were depressed, although a broad range of responses were observed ranging from very poor to near normal responses. SPA and PWM were the most potent mitogens in the CTCL patients, unlike controls in whom PHA and SPA were the optimum mitogens and PWM was weakly mitogenic. FMF studies in two patients clearly demonstrated that aneuploid Sezary cells and not admixed normal lymphocytes were proliferating in response to SPA and PWM stimulation. The unusual pattern of mitogen responses found in these CTCL patients suggests Sezary cells may be derived from T-cell subpopulations with special affinity for SPA and PWM. The ability of FMF to demonstrate that aneuploid cells respond to mitogen stimulation makes it a useful additional technique in the evaluation of lymphocyte blastogenesis in patients with malignant lymphoproliferative disorders.

Decreased autologous mixed lymphocyte reaction in Sjögren's syndrome

The autologous mixed lymphocyte reaction (AMLR) measures the response of peripheral blood T cells to antigens present on the surface of non-T cells. The AMLR was studied in 25 patients with Sjögren's syndrome (SS). The AMLR was decreased in 15 of 25 (60%) of patients with SS (5,272 +/- 6,738 cpm vs. 14,396 +/- 10,092 cpm for the normal controls, P < 0.001). The AMLR was decreased in 8 of 15 patients with only glandular disease who were not on any systemic medications. Patients with SS and associated disease had lower responses than patients with SS alone. Two patients with pseudolymphoma had absent response. The decreased AMLR correlated with a decreased response to concanavalin A, suggesting a possible abnormality of a T cell subpopulation. There was no correlation between the decreased AMLR and age, focus score, serum immunoglobulin concentration, the titer of antilymphocyte antibody, or phytohemagglutinin response. In allogeneic MLR, SS non-T cells and macrophages stimulated normal allogeneic T cells less well than normal non-T cells and macrophages, suggesting a possible abnormality in the cells that stimulate in the cells that stimulate in the allogeneic MLR.

Characterization of human lymphocytes which proliferate "spontaneously" in vitro

Human peripheral blood lymphocytes proliferate "spontaneously" in vitro following the reduction in the proportion of monocytes in culture. This cell proliferation, which takes place in the absence of any extrinsic antigenic stimulation, was found to reside in a small fraction of a non-T non-B cell population which was also Fc receptor-negative. Concomitant with the in vitro proliferation of the monocyte-depleted cells, an increase in the proportion of E rosette-forming cells was observed. Hence, in addition to the regulation of spontaneous proliferation of lymphocytes, it is suggested that monocytes may also be involved in the regulation of the proportion of T cells or in expression of the E-rosetting marker.

Lyt 1 cells respond to Ia-bearing macrophages in the murine syngeneic mixed lymphocyte reaction

An autologous mixed lymphocyte reaction has been described in mice and humans in which T cells proliferate following stimulation with syngeneic non-T cells. This report demonstrates that in the murine syngeneic mixed lymphocyte reaction, the responder cell is an Ly1+, Ly23-, Qa-1-T cell. The stimulator is an Ia-bearing macrophage-like cell.

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.

Autologous mixed lymphocyte reaction in patients with Hodgkin's disease. Evidence for a T cell defect

The proliferative response of T lymphocytes cultured with autologous non-T lymphocytes is known as the autologous mixed lymphocyte reaction (MLR). This reaction can be demonstrated reproducibly in healthy individuals and has been shown to generate specific cytotoxic T cells, as well as T cells that regulate antibody synthesis and cell-mediated immunity. In this study, we demonstrate that the autologous MLR is impaired or absent in most patients with Hodgkin's disease regardless of age, sex, pathologic stage, or histologic classification. In 64 patients, the mean autologous MLR was 3,084+/-1,878 cpm compared to 16,552+/-6,532 in 29 healthy donors. A defect in autologous MLR was observed in newly diagnosed patients before the initiation of therapy, but was also found in patients without evidence of recurrent disease up to 15 yr after treatment. These findings could not be explained by abnormal kinetics or poor viability of stimulator or responder cells. The possibility that suppressor cells are responsible for the reduction of T cell autoreactivity was examined by comparing the autologous MLR of a healthy HLA-identical sibling in the presence and absence of T or non-T cells of an affected sibling. No inhibitory effects were observed. Similarly, substitution of patient plasma for pooled AB serum failed to inhibit the autologous responses of normal donors. Increasing the number of responder T cells in the culture or removing adherent cells from the stimulator population enhanced autoreactivity in some patients, indicating that the defect is not absolute. In two families, T cells of healthy HLA-A, B, and DR-identical siblings of patients responded normally to the non-T cells of their affected siblings, whereas patients' T cells failed to respond both to their own stimulator cells and those of their healthy HLA-identical siblings. These data indicate that the impairment of autologous MLR in some patients is due to a reduction or dysfunction of responder T cell activity and not to a defect of autologous stimulator cells.

Is the MHC a general self-recognition system playing a major unifying role in an organism?

From the review of several recent observations of cell-cell interactions, which occur preferentially in autologous or syngeneic situations such as rosettes, adhesion, homing, and contact inhibition, the existence of an active general process of cellular self-recognition, not limited to the immune system, is postulated. This process is MHC associated or dependent, and seems to require an identity of ubiquitous molecules of class I--or other linked gene products at the surface of interacting cells. In contrast, class II molecules are not apparently implicated in general self-recognition. The immune system is regarded as a late evolution from a self-recognition system. It retains the ability of self-evolution, but possesses the exclusive property of active discrimination against foreignness. The astonishing fact that identity of MHC products seems to be needed for recognition is discussed in the context of various possible mechanisms. From immunological and genetical consideration, it is proposed that the genuine biological role of the MHC would be that of a self-recognition and unifying system.

The cellular basis of impaired T lymphocyte functions in the elderly

Immunologic changes associated with aging were studied by various immunologic tests in 24 aged persons (age range, 76-83) and 25 young persons (age range, 20-40). The responses to phytohemagglutinin (PHA) and concanavalin A (Con A) were depressed in the aged subjects compared to the young ones (p less than 0.05), whereas the responses to pokeweed mitogen (PWM) were similar. The activity of adhereent and non-adherent cells was assessed in various combinations. The adherent cells of aged persons were indistinguishable from those of young persons in their ability to response to Con A. Lymphocytes from the aged synthesized larger in vitro amounts of immunoglobulin than did lymphocytes from the young, when stimulated with PWM. Con A-stimulated T lymphocytes derived from aged subjects showed a variable loss of suppressor activity. The mixed lymphocyte culture reaction with mitomycin-treated allogeneic and autologous cells was also impaired in aged subjects. Such an impaired response in the aged is related to higher incidences of malignant lesions and auto-antibodies.

Studies of lymphocyte proliferation in hairy cell leukaemia: activity in mixed lymphocyte reaction and responses to mitogens

Subpopulations of splenic lymphocytes from patients with hair cell leukaemia (HCL) were compared with similar subpopulations of lymphocytes from reference individuals for their ability to respond to mitogens and to participate in allogenic and autologous mixed lymphocyte reactions. T cell enriched subpopulations were obtained by double passage of mononuclear cells through mylon wool columns. Non-T cell subpopulations were collected by eluting adherent cells from nylon wool columns and by incubating them with sheep erythrocytes followed by density gradient centrifugation. Unfractionated mononuclear cells, T enriched and non-T subpopulations were compared. Enriched T cell subpopulations from HCL and reference patients responded similarly to allogeneic antigens and phytohaemagglutinin. Splenic non-T cells from reference patients produced a stronger stimulus in the allogeneic mixed lymphocyte reaction than did the unfractionated or the T enriched cells. In contrast, the non-T subpopulations from patients with HCL produced a reduced response compared to that of reference splenic cells when mixed with allogeneic lymphocytes. In addition, non-T cells from HCL patients failed to respond to pokeweed mitogen. Neither reference nor HCL splenic cells produced a significant response in the autologous mixed lymphocyte reactions. The data suggest that splenic non-T cells from patients with HCL either suppress the stimulatory capacity of normal B lymphocytes or fail to stimulate allogeneic lymphocytes in the mixed lymphocyte reactions.

Cell-mediated immune responses between HLA-identical siblings: recognition of antigenic changes associated with acute myelogenous leukaemia

Cell-mediated immune reactions between a patient suffering from acute myelogenous leukaemia (AML) and an HLA-identical sibling were studied in order to characterize the in vitro reactions in MLC and CML prior to bone marrow transplantation. Our results indicated that antigenic differences were detectable between the blasts and the remission lymphocytes. While the normal sibling did not respond in MLC to her HLA-identical sister's remission lymphocytes, there was an anti-blast response. This proliferative response, however, did not lead to the development of detectable cytotoxic cells capable of destroying blast cells. Unrelated individuals, on the other hand, responded strongly both in MLC and CML to the allogeneic tumour blasts and remission lymphocytes of the patient and the lymphocytes of the healthy sibling. The kinetics and magnitude of the MLC response to blast cells was different from that to remission lymphocytes. This response indicated that the blast cells expressed antigenic differences which were recognized in MLC by both the HLA-identical sibling and unrelated individuals. Furthermore, these tumour cells were capable of sensitizing allogeneic, but not syngeneic lymphocytes to become cytotoxic, though they seemed to be more resistant to destruction in CML than normal cells.