Liver biopsies from 5 patients with established fascioliasis, before and after bithionol treatment were studied by immunoalkaline phosphatase technique for relative distribution of T cells and their subpopulations. T cell and its subsets are defined for OKT3+ (pan T), OKT4+ (helper/inducer) and OKT8+ (suppressor/cytotoxic) cells by using mouse monoclonal antibodies. Before bithionol treatment, lymphocytic infiltration in all hepatic lesions were predominantly of OKT3+ (pan T) lymphocytes. The

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... stribution of OKT8+ cells was moderate to severe in comparison to the few OKT4+ cells presentation. After bithionol a noticeable regression of the OKT3 lymphocytic in all liver sections. The majority of the lymphocytic infiltration was of the OKT8+ cells, in comparison to the absence of the OKT4+ ones. This may indicate that suppressor/cytotoxic lymphocytes may have a role in the immune regulation of the disease and the mode of action of bithionol is by the accentuation of this immunoregulatory effect.