Expression of CD10 by CD4⁺ T cells induced into apoptosis in vitro. (A) Purified CD4⁺ T cells were exposed to SEB and/or CD4 MoAb under cross-linking conditions in different combinations as indicated. The cells were obtained after 24 hours and CD10 expression and apoptosis (PI staining) were measured by flow cytometry. (B) RT-PCR analysis of CD10 mRNA expression in CD4⁺ T cells exposed to the indicated stimuli for 24 hours in vitro. Burkitt’s lymphoma B cells (LAM cell line) were used as positive control. (C) Alu I esonuclease digestion and analysis of the RT-PCR fragments extracted from the indicated cells. These results represent a typical experiment of the 3 performed.