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Conflicting data on subpopulations of peripheral blood lymphocytes in patients with autoimmune disease largely reflect variations in methods of study. An investigation was therefore conducted aimed at avoiding this difficulty. Serial samples of peripheral blood mononuclear cells from 42 patients with hyperthyroid Graves' disease were collected at monthly intervals before, during, and for 12 months after a six month course of carbimazole. Samples were stored in liquid nitrogen until completion of the study, when they were thawed and all samples from each patient analysed within the same assay using mouse monoclonal antibodies to human cell subsets and a fluorescence activated cell sorter. Proportions of cytotoxic/suppressor (OKT8) positive cells before treatment (mean 17.4 (SEM 0.8)%) were significantly lower (p less than 0.001) than those in normal controls (29.8 (1.9)%; n = 10) and returned to normal by the end of treatment. In contrast, the proportions of activated T cells (OKIa-OKM1) were significantly raised before treatment as compared with normal (14.4 (0.6)% versus 4.6 (0.8)%; p less than 0.001) and fell to normal by the end of treatment. Proportions of OKT3 and OKT4 positive T cells remained unchanged throughout treatment and in the succeeding 12 months. In patients who relapsed after treatment there was a rise in the proportion of activated T cells and a fall in OKT8 positive T cells, which returned towards normal with retreatment. The explanation for the alterations in numbers of circulating T cells remains to be determined but they may provide a means for predicting more accurately the outcome of Graves' disease after treatment with carbimazole.

The clinical utility of ELISA assays for antibodies reactive with a variety of porcine orbital tissue antigen preparations is described using sera from large numbers of patients. Use of such assays does not allow reliable identification of patients with Graves' ophthalmopathy (GO) due to the overlap between patients with and without eye involvement and normal individuals. In 5 6 patients showing high levels of reactivity with porcine eye muscle membrane antigen, a considerable but variable proportion of the binding was found to be species, rather than tissue, specific. No consistent pattern of change in ELISA reactivity with time was seen in studies of serum samples from patients treated medically for hyperthyroidism and patients who received immunosuppressive therapy with cyclosporin A for active, severe ophthalmopathy. Use of previously published ELISA methods using the crude antigen preparations described is therefore not likely to be of use in the routine clinical management of GO patients.

A study was conducted investigating the possibility that the immunosuppressive action of methimazole (the active metabolite of the antithyroid drug carbimazole) might be due to an effect on the production of oxygen radicals by monocytes. Techniques comprised measurement of luminol dependent chemoluminescence in monocytes and a spectrophotometric assay for production of hydrogen peroxide. The results showed definite inhibition of formation of oxygen radicals by resting and stimulated monocytes, which may explain the immunosuppressive action of the drug in Graves9 disease. The findings also suggest that the formation of oxygen radicals and the initiation of the immune response may be closely related.