The frequency of CD4⁺CD8^-CD25⁺ thymocytes in patients with MG is similar to healthy newborn and young adult thymi. Freshly isolated human thymocytes from hyperplastic thymi of 15 patients with MG as well as the thymocytes from 10 young adult and 10 newborn thymi were analyzed by 3-color flow cytometry for the expression of CD4, CD8, and CD25. Each point represents 1 patient or 1 control. The bars represent mean values. The proportion of CD4⁺CD8^- cells with CD25⁺ (A) as well as CD25^hi (B) expression was calculated. The differences between newborns, adults, and patients with MG are not significant (NS).