Prevention of autoimmunity in experimental lupus erythematosus by soluble immune response suppressor

Regulatory T cells in systemic lupus erythematosus: past, present and future

Regulatory/suppressor T cells (Tregs) maintain immunologic homeo-stasis and prevent autoimmunity. In this article, past studies and recent studies of Tregs in mouse models for lupus and of human systemic lupus erythematosus are reviewed concentrating on CD4⁺CD25⁺Foxp3⁺ Tregs. These cells consist of thymus-derived, natural Tregs and peripherally induced Tregs that are similar phenotypically and functionally. These Tregs are decreased in young lupus-prone mice, but are present in normal numbers in mice with established disease. In humans, most workers report CD4⁺Tregs are decreased in subjects with active systemic lupus erythematosus, but the cells increase with treatment and clinical improvement. The role of immunogenic and tolerogenic dendritic cells in controlling Tregs is discussed, along with new strategies to normalize Treg function in systemic lupus erythematosus.

Modulation of SLE induction in naive mice by specific T cells with suppressor activity to pathogenic anti-DNA idiotype

T cells (CD8+) with specific suppressor activity against anti-dsDNA antibody (16/6 Id+) were generated in vitro. The cells were established from BALB/c-enriched T cells exposed in vitro to silica beads coated with the pathogenic anti-DNA idiotype, 16/6. The idiotype specificity of the suppressor cells was demonstrated by (a) specific induction of a decrease in proliferative response of T helper cell lines specific for the pathogenic idiotype (16/6 Id), when exposed to the idiotype, with no effect on T cell lines with other specificities, e.g., against human IgM or synthetic polypeptide. (b) Effectively suppressing in vitro antibody production of anti-16/6 antibody, employing 16/6-primed B cells and specific helper T cell line. The 16/6 Id-specific Ts cells were found to be MHC restricted. Weekly intravenous injections of 10(7) 16/6 Id-specific Ts cells given to BALB/c mice at different stages of experimental SLE disease prevented the clinical, serological, and pathological manifestations. This effect was characterized by decreased titers of autoantibodies (e.g., anti-DNA, anti-Sm antibodies) in the sera, by abolishment of the proteinuria, leukopenia, and the increased ESR, followed by decreased immunoglobulin deposition in the kidneys. Treating the mice with control IgM-specific T cells did not affect the above parameters. These studies demonstrate the ability to generate Ts cells specific for pathogenic idiotypes. The method might be employed therapeutically to modulate the course of autoimmune conditions.

The significance of T suppressor cells in the development of autoimmunity

Despite intensive research, autoimmune-disease pathogenesis is still an enigma, but in the past decade Ts-cell defects have assumed a central role in this pathogenesis. Ts-cell dysfunctions have been reported in numerous autoimmune diseases (e.g. SLE, autoimmune thyroid disease, myasthenia gravis) and in animal models of autoimmune diseases. Therefore, it is currently believed that Ts cells are responsible for maintaining self-tolerance and that perturbations in suppressor functions may initiate development of autoimmune diseases. Ts-cell abnormalities can result from LCTA production, intrinsic biochemical alterations, genetic susceptibility, or environmental factors. Since Ts-cells dysfunctions are believed to initiate autoimmunity, it may be possible to treat autoimmune diseases by correcting the suppressor defects, and indeed, preliminary trials in this direction are promising.

Prevention of lupus diseases in MRL/1, NZBxNZW, and BXSB mice treated with a cyclophosphazene derived drug

A polyclonal activation of lymphocytes (PA) has been suggested to play a pathogenic role in autoimmune and immune complex diseases, particularly in mouse lupus. "DIAM 4," a cyclophosphazene derived drug, selected on the basis of its ability to modulate a PA has been used to treat female MRL/1, female NZBxNZW, and male BXSB mice. In these three strains of mice, the treatment was found to induce an inhibition of the PA, to prevent the increase of anti-DNA antibody levels and the simultaneous decrease of C3 levels, to prevent the appearance of proteinuria, the deposition of immune complexes in glomeruli, and the development of kidney lesions. Moreover in MRL/1 mice, lymphoproliferation was prevented. These results suggest that drugs able to modulate a PA might be efficient in the treatment of mouse lupus nephritis. Such a principle of immunomodulation might open the way to new possibilities of treatment of lupus and other immune complex diseases.

Spleen cell factor inhibits lymphoproliferation, abnormal Ia expression and overt autoimmunity in MRL-lpr mice

Autoimmune MRL-lpr have an abnormal pattern of lymphokine production. In our attempt to repair this defect, MRL-lpr mice were prophylactically treated daily with a lectin stimulated rat spleen cell product rich in interleukin-2. Therapy inhibited the lymphoid hyperplasia of the unique lymphocytes regulated by the lpr gene, suppressed the enhanced supranormal expression of Ia on peritoneal macrophages and protected this strain from autoimmune renal injury. Purified recombinant interleukin-2 alone did not prevent autoimmune disease expression. Thus, a spleen cell product other than interleukin-2 can ameliorate the aggressive course of lymphoproliferation and autoimmunity in MRL-lpr mice.

Potential use of human interleukin 2 as an adjunct for the therapy of neoplasia, immunodeficiency and infectious disease

Experimental and clinical systems have been developed to analyze both the in vitro and in vivo effects of highly purified interleukin 2 (IL2) as a potential therapeutic adjunct for neoplasia, immunodeficiency and infectious disease. Animal models, clinical in vitro studies, as well as preliminary clinical trials of IL2 in vivo show that this lymphokine may provide a necessary signal for the activation of thymus-derived T cells in immunologically-compromised hosts.

Soluble suppressor factors in patients with acquired immune deficiency syndrome and its prodrome. Elaboration in vitro by T lymphocyte-adherent cell interactions

Supernatants from peripheral blood mononuclear cells obtained from certain patients with the acquired immune deficiency syndrome (AIDS) or its prodrome were capable of depressing spontaneous and pokeweed mitogen-driven B lymphocyte differentiation into plasmacytes, and the proliferative responses of T cells to specific antigen. These soluble suppressor factors (SSF) were present in uniquely high concentrations, with significant differences from healthy controls and from patients with various other conditions previously associated with factor-mediated immunosuppression. T cell-independent functions were not modified by SSF. Suppression was not genetically constrained, and did not appear to be mediated by cytotoxicity, prostaglandin, or alpha or gamma interferons. SSF was a product of the interaction of T lymphocytes with adherent cells. T cells or T cell factors from AIDS patients, but not from normal controls, could collaborate with control adherent cells in the formation of SSF. Restoration of DNA synthesis-independent differentiation of B lymphocytes into plasmacytes in SSF-treated cultures was realized by addition of reducing agents, such as 2-mercaptoethanol, on culture initiation. These data suggest inhibitory mechanisms possibly related to that of concanavalin A-induced soluble immune response suppression, and perhaps offer clues to clinically applicable substances which are potentially capable of mitigating such responses.

Immunoregulatory cells in aging mice. I. Concanavalin A-induced and naturally occurring suppressor cells

The status of concanavalin A (Con A)-triggered suppressor cells in aging mice was assessed in relation to untreated cells. Spleen cells of (C3H/ebJ X C57BL/6J)F1 and (BALB/cJ X C57BL/6J)F1 aging (20-41 months' old) and young (2-3 months' old) mice were triggered with Con A and examined for their capacity to suppress lymphocyte proliferative responses elicited by mitogens (Con A and phytohemagglutinin), by mixed lymphocyte reactions or by human gamma-globulin. Con A-triggered cells of the aging mice were found to be less efficient suppressors than those of the young, yet the aging mouse spleen cells exerted a more potent suppressive effect than the young, a priori, without pretreatment. Hence, the immune system in aging is characterized by a change in suppressor cell types; the Con A-triggered suppressors diminish and the naturally occurring, untreated ones become abundant.

Natural killer augmentation in systemic lupus erythematosus via a soluble mediator derived from human lymphocytes

Seventeen patients with diagnosed systemic lupus erythematosus were studied for natural killer activity and the ability of a human soluble immune-response factor to modify this activity. Defective natural killer activity was found in patients with systemic lupus erythematosus regardless of the stage of disease, medication, or organ system involvement (24.6% versus 47.8% cytotoxicity). After treatment with the immune-response factor, the natural killer activity increased in all patients, with a mean of 47.3% compared with 24.6% before treatment. This product has other immunologic activities and was shown to be free of interferon. The mechanism of action is not yet known, but such an immune-response factor has potential use in the treatment of systemic lupus erythematosus.

Inhibition of Con A mitogenesis by serum from procainamide-treated patients and patients with systemic lupus erythematosus

Serum obtained from patients with spontaneous systemic lupus erythematosus or from patients treated at least 3 months with procainamide could specifically inhibit Con A mitogenesis of cultured peripheral blood mononuclear cells obtained from procainamide-treated patients or from normal donors. Transfer of procainamide treated patients to N-acetylprocainamide eliminated the blocking factor from their serum. The blocking factor is not procainamide itself since adding the drug to normal serum and only slight effects on mitogenesis of normal peripheral blood mononuclear cells. These data suggest that systemic lupus erythematosus and procainamide-induced lupus may differ in the relative reversibility of a regulatory defect associated with a Con A responsive population of peripheral blood mononuclear (PBM) cells.

Spontaneous suppressor cell function in inflammatory bowel disease

We investigated suppressor cell activity in the peripheral blood of 39 patients with inflammatory bowel disease (30 Crohn's disease and 9 ulcerative colitis) by the short-lived suppressor cell assay. There was a significant decrease in the suppressor cell activity in patients with inflammatory bowel disease (IBD), compared to 26 healthy subjects studied simultaneously. Five other patients with acute bacterial infections had normal suppressor activity. A group of 14 IBD patients was also investigated for concanavalin A-induced suppressor cell activity and decreased suppressor function was confirmed. A significant positive correlation was found between the two assays. A defect in suppressor cell activity may permit the expression or maintenance of immunologically mediated damage to the gut in IBD.

Acetylator phenotype and lupus erythematosus

There are several known therapeutic implications of acetylator phenotype; among them, the association of a higher incidence of procainamide- and hydralazine-induced lupus in slow acetylators. Presumably, this is because acetylation of the aromatic amine or hydrazine functional group leads to a non-toxic product. Several other drugs which have been implicated in drug-induced lupus also contain an aromatic amine or hydrazine group. The clinical and laboratory characteristics of drug-induced and idiopathic lupus are similar but the degree to which the pathophysiological mechanisms are related, if at all, is unknown. There is also evidence reported for an association between the slow acetylator phenotype and idiopathic lupus. If true, this relationship should provoke some new experimental approaches to investigation into the mechanism of idiopathic lupus.

A comparison of cell-mediated immunity and suppressor T-cell function in asthmatic and normal children

The role of general and suppressor T-cell function was investigated in a group of twelve children with atopic asthma and ten non-atopic control children. Studies of active E rosettes, lymphocyte stimulation, and delayed type skin responsiveness revealed no statistically significant group differences. Data obtained employing a concanavalin A-induced, suppressor T-cell assay revealed that the asthmatics generated significantly less suppressor cell activity than did the normal control group. There was no correlation between lack of suppressor cell function and serum IgE levels. The results of this study support the concept of suppressor T-cell dysfunction in atopic disease.

Effects of concanavalin A-stimulated spleen cell supernate on the redevelopment of autoimmunity in NZB/NZW mice in induced remission

Because female NZB/NZW mice develop autoimmune abnormalities similar to those encountered in human systemic lupus erythematosus (SLE), a group of female NZB/NZW mice were used to study mechanisms of autoimmunity. These mice were treated daily with an immune suppressive material, 0.5 ml of a concanavalin A-stimulated spleen cell supernate (CONS), starting at 30 weeks of age after induced remission with prednisolone. This CONS treatment effectively reduced the proteinuria and the severity of the renal lesions, but failed to reduce the serum anti-DNA antibody level. Thus, the CONS effect on the autoimmunity in the NZB/NZW mice in induced remission appears to result from a more complicated mechanism than reduction in serum anti-DNA antibody level.

Immunoregulation in New Zealand mice. I. Failure of the transfer of syngeneic spleen or thymus cells to influence the natural disease in New Zealand mice

Young, syngeneic thymocytes and spleen cells were administered to F1 hybrids of New Zealand Black by New Zealand White (NZB/W) mice beginning at 3 weeks of age and were continuted at 2-week intervals for 8 to 9 months. The development of autoimmunity as assessed by measuring the incidence and level of anti-DNA antibody, the degree of renal involvement, and the survival of recipient mice was evaluated and compared to a control group of animals. No significant differences were noted in these parameters in mice receiving cell transfers as compared to the control group. Therefore, in contrast to other reports, these results suggest that the transfer of young thymus or spleen cells into aging NZB/W mice fails to influence immunoregulation and the subsequent development of autoimmunity.

Suppressor cell function in multiple sclerosis: correlation with clinical disease activity

Concanavalin A (Con A)-activated suppressor cell activity was determined in multiple sclerosis (MS) patients who had been assigned to one of three subgroups, those with active disease, those recovering from a flare-up, and those with stable disease. The level of suppression induced by the Con A-activated suppressor cells on the mitogenic response of autologous peripheral blood lymphocytes was reduced in patients with active disease (3 +/- 8%) compared with stable patients (30 +/- 8%), patients recovering from a flare-up (62 +/- 5%), and controls (40 +/- 5%). As a measure of the actual amounts of suppressor factors released, the effect of supernatants from the Con A-activated cells on the proliferative activity of a dividing cell line (L cells) was determined concurrently. The inhibitory effect of supernatants from activated cells was reduced in active and stable MS patients (7 +/- 3%) compared to controls (21 +/- 4%). Three of 4 with active MS showed mildly elevated immune complex levels as measured by the Raji cell technique; each of these patients had low suppressor activity. Levamisole (1 microgram per milliliter) failed to alter suppressor cell activity in our in vitro system.

Ribavirin treatment in murine autoimmune disease. I. Therapeutic efficacy and effect on the immune response

NZB/W F1 female mice were treated from 20 weeks of age with ribavirin (a broad spectrum antiviral drug), cyclophosphamide, or saline. Treatment with ribavirin (250 mg/kg twice weekly) prolonged survival from 9.8 to 18.5 months, reduced anti-DNA antibodies, and prevented proteinuria. Ability of ribavirin to prolong survival was dose related when given on a twice weekly schedule. However, daily ribavirin (25 mg/kg/day) was as effective as higher intermittent doses. Optimal ribavirin therapy was equal to cyclophosphamide treatment with regard to prolongation of survival. Ribavirin treatment did not significantly alter the body weight, hematocrit, WBC count, serum immunoglobulins, or Coombs reactivity. No alterations in either cellular or humoral immune responses were noted in NZB/W F1 or BALB/c mice treated for prolonged periods with ribavirin. The impressive therapeutic response to a broad spectrum antiviral agent seen in mice already manifesting immune complex nephritis provides a new therapeutic approach to the treatment of autoimmunity.

Studies of immune functions of patients with systemic lupus erythematosus. I. Dysfunction of suppressor T-cell activity related to impaired generation of, rather than response to, suppressor cells

T cell suppressor function in patients with systemic lupus erythematosus (SLE) was evaluated by studying the ability of concanavalin A- (Con A) activated T cells to suppress proliferative responses by responder cells autologous with the Con A-activated T cells. Impaired suppressor T-cell activity in patients with SLE was observed with regard to three effector functions: 1) the allogeneic response of T cells, 2) the Con A response of T cells, and 3) the B cell response to pokeweed mitogen (PWM). No defect was found with regard to suppression of the T-cell response to phytohemagglutinin (PHA). Mixing experiments between SLE and normal cells were carried out to further define the nature of the SLE suppressor defect. When responder cells from SLE patients were cultured with Con A-activated T cells from normal controls, the normal suppressor T cells caused suppression of SLE responder cells. In contrast, Con A-activated T cells from SLE patients were incapable of exerting suppressor effects on normal responder cells. These observations indicate that the impaired suppressor activity in SLE patients resides in the generation of suppressor T cells, rather than in the response to suppressor T cell signals.

Therapeutic studies in NZB/NZW mice. VI. Age-dependent effects of concanavalin A stimulated spleen cell supernate

Spleen cells from normal mice were cultured with Concanavalin A to produce an immunosuppressive supernate. This supernate was used to treat the lupus-like autoimmune disease of NZB/NZW mice. Such treated mice lived significantly longer than did controls, but only if treatment was initiated early in the course of the illness.