Design of potent linear PAF antagonists.
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Biomedical subjects
Publications and source records attributed to M Giral.
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1. Several platelet activating factor (PAF)-antagonists of different chemical structures were tested in the arachidonic acid-, tetradecanoylphorbol acetate-, dithranol-, and benzoic acid-induced mouse ear oedema models. 2. Topical application of UR-10324, UR-11353, CV-6209 and WEB-2086 markedly inhibited ear oedema induced by the four irritants tested, mimicking the profile obtained with dexamethasone. YM-461 was highly effective only in the dithranol-induced ear oedema, while BN-52021 failed to inhibit ear oedema in all models tested. 3. Leukocyte recruitment into the inflamed ears was prevented by PAF-antagonists, as measured by myeloperoxidase activity in the supernatants of ear homogenates. 4. A relationship between PAF-antagonist and anti-inflammatory activities was found in some cases, but other mechanisms cannot be excluded to explain the topical anti-inflammatory effect of these compounds. 5. Our results suggest that topical formulations containing PAF-antagonists could be useful in the treatment of some inflammatory skin diseases and provide evidence on the involvement of PAF in these inflammatory processes.
Interleukin-2 is a major growth factor for activated T lymphocytes, and antibodies reacting with the Tac-chain component of the interleukin-2 receptor can prevent allograft rejection in animals. Because Tac chains are expressed only on a small fraction of activated lymphocytes, monoclonal antibodies against the interleukin-2 receptor may offer a more specific means of immunosuppression than polyclonal antilymphocyte globulin in prophylaxis against graft rejection. Therefore, we compared the immunosuppressive effect of 33B3.1, a rat monoclonal antibody against the human Tac chain, with the effect of a rabbit polyclonal antithymocyte globulin in a randomized study of 100 recipients of first renal transplants. Injections of 33B3.1 (10 mg per day) were tolerated well, whereas major side effects in 15 of 47 patients (32 percent) receiving antithymocyte globulin required discontinuation of treatment before day 14. The incidence of rejection episodes was not statistically different in the two groups at days 14, 30, 60, and 90 after transplantation. Patient and graft survival was also equal in the two groups at one year (96 and 85 percent, respectively, in both groups), and graft function was similar. The total number of infectious episodes within the first three months was lower in the 33B3.1 group than in the antithymocyte group (47 vs. 72). The drop in peripheral-blood lymphocyte concentrations was significantly larger in the patients treated with antithymocyte globulin. The level of circulating Tac-chain-bearing lymphocytes remained below 1 percent during 33B3.1 treatment, as compared with 4 to 5 percent during antithymocyte-globulin treatment (P not significant). We conclude that 33B3.1 is as effective as antithymocyte globulin in the prevention of renal-transplant rejection, and its use results in fewer infections and side effects.
Monoclonal antibodies (MoAbs) against human interleukin 2 receptor (IL-2-R) have been shown to prevent early kidney rejection in animals and humans. We report here the effect of an anti-IL-2-R MoAb (33B3.1) inhibiting IL-2 binding high-affinity sites on activated lymphocytes in 10 declared acute rejection episodes of first cadaveric kidney grafts. Six patients were under cyclosporine treatment only at the time of diagnosis of the rejection. All rejection episodes but one were biopsy-proved cellular rejections. Treatment consisted of intravenous infusions of 33B3.1 at 20 mg/day x 2 days, followed by 10 mg/day for 8 additional days. In case of MoAb ineffectiveness at day 5, anti-IL-2-R MoAb was discontinued and a rescue treatment of corticosteroid boluses (CSb) was given. If not, in all cases corticosteroids (CS) were given (1 mg/kg) at the end of MoAb treatment (day 10) and tapered off thereafter. Two rejection episodes immediately responded to 33B3.1 treatment. During 33B3.1 treatment four other patients had only a stabilization of their blood creatinine concentration, which nevertheless returned to prerejection levels after day 10 when anti-IL-2-R was discontinued and CS administered at 1 mg/kg (no rescue treatment). The four remaining patients had an increase of their blood creatinin levels at day 5 despite 33B3.1 treatment, and their renal function only improved with CSb rescue treatment. One of these patients lost the graft despite rescue treatment, as well as a 9-day course of antithymocyte globulin. Trough levels of MoAb reached a plateau as early as day 2 (approximately 6 micrograms/ml). All patients developed antibodies (IgM and IgG) after day 14. In no instance could unresponsiveness be related to low circulating 33B3.1 trough levels or to early host anti-MoAb immune response (IgM or IgG). We conclude that 33B3.1, known to be effective in preventing early rejection, has only inconsistent and/or incomplete effects on the ongoing rejection process. Our data suggest that once IL-2-dependent clones are expanded in the rejected graft, interference with IL-2/IL-2-R signals does not block the effector mechanisms sustaining acute rejection.
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