ABSTRACT
The flowing cytofluorometric and electron microscopic methods have been used to study the content and ultrastructure of blood CD4 lymphocytes in healthy and type I diabetic patients. Analysis of submicroscopic structure of the lymphocytes expressing CD4 antigen has revealed its morphological heterogeneity. It has permitted distinguishing four groups of cells. A decrease of the content of CD4+ lymphocytes at the expense of the first group cells and relative increase in the number of the fourth-group cells are observed in the majority of diabetic patients. The availability of parallel-tubular structures in granules forming clusters and first-group lymphocytes, an increase in the number and size of granules of the fourth-group are the most typical changes of ultrastructural characteristics.