Figure 8.

The CD8⁺CD25⁺ cells induced with hOKT3γ1(Ala-Ala) suppress CD4 cell response to SEB and IFN-γ secretion. (A) CD8⁺CD25⁺ or CD8⁺CD25^– cells sorted from PBMCs stimulated for 6 days with hOKT3γ1(Ala-Ala) or CD8⁺ cells from fresh PBMCs were irradiated and cocultured for 3 days with fresh PBMCs depleted of CD8 in the presence of SEB. Proliferative response was assessed by [³H]thymidine uptake. (B) The levels of IFN-γ in the supernatants from the same cultures were measured by Luminex system using Th1/Th2 multiplex microspheres. Representative results of 2 independent experiments are shown. (C) Sorted CD8⁺CD25⁺ (bottom panel) or untreated CD8 cells (upper panel) were cocultured for 6 days with CFSE-labeled, CD8-depleted PBMCs at 1:2 ratio in the presence of SEB. SEB-specific clonal expansion was analyzed by flow cytometry. The expansion of Vβ3-positive CD4 (M1) lymphocytes was reduced from 46.1% to 15.5% of Vβ3⁺ T cells. Similar results were obtained in 2 additional studies.