Functional defect of T cells in autoimmune gastritis.

The functional response and phenotypic characterisation of peripheral blood T cells were studied in 41 patients with autoimmune gastritis--nine patients with autoimmune gastritis alone, 11 with untreated pernicious anaemia, and 21 with resolved pernicious anaemia who were taking vitamin B-12. Phenotypic analysis showed no changes in the CD4/CD8 ratio in any group of patients. CD3+ cells were significantly decreased and CD16+ cells were significantly increased in patients with autoimmune gastritis alone. Phytohaemagglutinin induced T cell proliferation, with or without interleukin 2, was reduced in the three groups. T cell proliferation induced by phorbol myristate acetate was normal. Interleukin 2 production of phytohaemagglutinin-stimulated lymphocytes was normal in the three groups. Five patients with pernicious anaemia treated with vitamin B-12 were followed and persistent hypoproliferation of T cells in response to phytohaemagglutinin was observed. The follow up study of the phenotype of these patients showed a significant increase of the CD2+ CD3- lymphocyte population after six months' treatment. In conclusion, the three groups of autoimmune gastritis patients studied have a functional defect in T cells that is independent of B-12 treatment and of the presence of pernicious anaemia.