The majority of the activated T cells in the blood of insulin-dependent diabetes mellitus (IDDM) patients are CD4+.

Twenty-five recently diagnosed insulin-dependent diabetic patients were screened for the presence of activated T lymphocytes using the anti-IL-2 receptor monoclonal antibody; thirteen had elevated levels of activated T lymphocytes. The activated cells were mostly confined to the CD4 subset, with the CD4/CD8 ratio in IL-2 receptor expressing cells averaging 5 +/- 1 (s.d.) compared with 1.3 +/- 0.3 for all T cells. In recent onset insulin-dependent diabetes blood there was no lack of CD4 CD45R+ (suppressor/inducer) T cells. The activated IL-2 receptor, expressing cells belonged to both CD4 subsets, 'helper inducer' (CD44B4) and 'suppressor inducer', (CD42H4).