Tumor necrosis factor alpha is released by monocytes in OKT3 monoclonal antibody immunosuppressive therapy.
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Anti-CD3 monoclonal antibodies are potent immunosuppressants widely used in clinical transplantation to prevent or treat acute allograft rejection. We have used a hamster monoclonal antibody (145 2C11) specific for the epsilon chain of the murine CD3 complex to treat autoimmune insulin-dependent diabetes appearing spontaneously by 15 to 30 weeks of age in female Non Obese Diabetic (NOD) mice. Mice showing overt disease (glycosuria and glycemia > or = 4 g/l) were randomized in two groups receiving either anti-CD3 (5 micrograms/day i.v. for 5 consecutive days) or an identical dose of hamster polyclonal immunoglobulins. Progressive remission of disease was observed, 3 to 6 weeks after the end of treatment, in 80% of anti-CD3 treated mice as compared to 6% of mice in the control group. This remission was maintained long term namely, during the 4 to 5 months (after the end of treatment) observation period. These results open interesting perspectives on the possibility to treat recently diagnosed diabetic patients with therapy showing long term efficacy and no chronic toxicity.
The thymic repertoire of neuroendocrine 'self' antigens has been previously described on the basis of the intrathymic expression of neurohypophysial (NHP)- and tachykinin-related peptide signals and receptors. According to that model, the cryptocrine signalling between thymic epithelial/nurse cells and thymocytes through NHP-related signals and receptors constitutes one accessory pathway in the process of T-cell differentiation and/or activation. A pharmacological manipulation of that novel type of cell-to-cell signalling was tested by the investigation of the immunomodulatory properties of novel cyclic hexapeptide oxytocin (OT) antagonists (MSD Research Laboratories). These compounds were found to significantly inhibit the productions of cytokines (mainly IL-1 beta and IL-6) elicited by anti-CD3 treatment of human whole blood cell cultures. Cytokine productions were more significantly reduced by OT antagonists in whole blood cell cultures derived from female volunteers than in those obtained from male donors, suggesting an influence of the gonadal steroid environment on the expression of NHP peptide receptors by immune cells. These observations support the concept of novel immunomodulating approaches through immune-specific neuropeptide antagonists, as well as the pharmacological value of such strategies in selective immunotherapy.
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Reported is a case of acute fulminant lymphocytic myocarditis with profound circulatory compromise that was successfully reversed by treatment with OKT3 monoclonal antibody. The patient was supported with biventricular assist devices while being treated with the monoclonal antibody. The patient had remarkable recovery of ventricular function, which allowed for the removal of the device after 8 days of support. This case shows the success of combined technologies of monoclonal antibody and mechanical circulatory support to treat a potentially fatal disease process.
Of 142 cardiac allograft recipients who underwent transplantation from December 1985 to January 1991, four women and seven men (mean age, 41 +/- 14 years) required multiple (10.5 +/- 3.3) courses of antirejection treatment over a total follow-up period of 30 +/- 15 months. The underlying heart disease was cardiomyopathy in six patients and coronary disease in five patients. These patients were treated with methotrexate (10 mg/wk for 6 weeks). Rejection treatment before methotrexate therapy included six courses of OKT3, one course of antithymocyte globulin, 33 courses of high-dose steroids, and 45 courses of low-dose steroids for the entire group. The average number of rejection treatments per patient before methotrexate therapy was 8.7 +/- 3.5 treatments or 0.90 +/- 0.51 treatments per month of follow-up. After methotrexate therapy the average number of rejection treatments fell to 1.7 +/- 1.1 treatments or 0.11 +/- 0.08 treatments per month of follow-up (p = 0.0002). Seven patients responded to a single course of methotrexate therapy; three patients required two courses (second course, 20 mg/wk for 6 weeks), and one patient required three courses of methotrexate therapy. The only complication associated with methotrexate therapy was one patient in whom cytomegalovirus interstitial pneumonitis developed while on therapy. Methotrexate was well tolerated and appeared to be effective in halting repeated episodes of rejection in this subset of patients who have had multiple episodes of acute rejection.
The growing knowledge on the pathophysiological role of cytokines in acute and chronic inflammatory processes stimulated efforts to control their synthesis and action pharmacologically in clinical situations. Recently, in our institute evidence was raised that pentoxifylline (POF) is able to suppress the synthesis of tumor necrosis factor-alpha (TNF) in cell cultures, in vivo, and to protect experimental animals against endotoxin shock. Studies in human experimental endotoxemia showed that pentoxifylline decreased circulating TNF without affecting endogenous formation of interleukins. The potency of this drug to interfere with TNF synthesis could also be demonstrated in cases of acute and chronic cytokine release syndromes such as OKT3 first-dose reaction and severe pulmonary tuberculosis, respectively. We suggest that POF may improve therapeutic strategies in various diseases in which TNF was identified as a causative pathophysiological factor.
Op18 is a highly conserved major cytosolic phosphoprotein that has been implicated in signal transduction in a wide variety of cell types. Freshly isolated peripheral blood lymphocytes (PBL) constitutively express low levels of mostly unphosphorylated Op18. After mitogenic stimulation of PBL, Op18 synthesis is induced at a time when cells are entering S-phase. In this study, we have examined the phosphorylation of Op18 in freshly isolated PBL after activation of the T cell receptor by OKT3. Quantitative analysis of Op18 phosphorylation was undertaken by metabolic labeling with 32Pi and PhosphorImager analysis of two-dimensional gels. After 10 or 15 min of activation by OKT3, one of the three major phosphorylated forms of Op18, designated Op18c, increased approximately 10-fold, which represented a most pronounced change among a large number of phosphoproteins analyzed. In time course experiments, increased Op18 phosphorylation to yield Op18c was observed as early as 2 min. Continued OKT3-induced activation for 20 to 72 h resulted in a further increase in phosphorylated Op18 forms, which paralleled new Op18 synthesis and occurred at a time when cells were entering S-phase, as determined by [3H]-thymidine incorporation. Inhibitors of lymphoid proliferation, cyclosporin A and RPM, had no effect on early (less than 15 min) phosphorylation. Addition of calphostin C, a specific inhibitor of protein kinase C, 1 min prior to stimulation of resting T cells with OKT3 completely inhibited further phosphorylation of Op18. Incubation of PBL with calphostin C for 75 min decreased constitutive levels of phosphorylated Op18. In contrast, inhibition of cyclic nucleotide-dependent protein kinases with HA1004 had no effect on Op18 phosphorylation. Activation of cAMP-dependent protein kinase with Forskolin or 8Br-cAMP did not increase Op18 phosphorylation. Our results suggest that Op18 phosphorylation is mediated by protein kinase C activation as an early event in T cell activation through the T cell receptor.