Characterization of T-cell clones generated from CD4⁺CD25⁺, CD8⁺CD25⁺, CD4⁺CD25^- thymocyte suspensions. (A) T-cell clones generated from purified CD4⁺CD25⁺ or CD8⁺CD25⁺ thymocytes were assessed for their ability to inhibit the proliferative response of CD4⁺CD25^- autologous thymocytes to allogeneic stimulation, as described in “Materials and methods.” Results are expressed as mean percentage of inhibition of proliferation obtained in triplicate cultures of each CD4⁺ or CD8⁺ T-cell clone. (B) T-cell clones generated from CD4⁺CD25⁺, CD8⁺CD25⁺, CD4⁺CD25^- thymocytes were assessed for their ability to produce IL-4 and/or IFN-γ by flow cytometry analysis at single cell level. Production of cytokines by each clone was considered as noteworthy when the proportion of producer T-cell blasts was higher than 10%.