The large CD25⁺ B cells mediate suppression of activated Th cells. (A) Proliferation assay of cCD3-stimulated Th cells alone or in presence of ^lgB25⁺ or ^smB25⁻ cells after 4 days in presence (■) or absence (▨) of IL-2. Bars represent mean of 9 independent experiments plus or minus SEM. (B) Proliferation of prestimulated () or freshly isolated (■) Th cells in presence of ^lgB25⁺ or ^smB25⁻B cells after 4-day culture with IL-2. Mean plus or minus SEM of 3 representative experiments. (C) Proliferation of Th cells in presence of different concentrations of ^lgB25⁺ cells, diluted in cell culture media (■) or in B25⁻ cells (). Data expressed as mean plus or minus SEM of triplicates from one representative experiment.