Soluble factors do not play a significant role in the suppression mediated by CD45RC^low CD8 T cells. Transwell culture experiments. CFSE-labeled CD4 T cells from LEW rats (5 × 10⁵ cells/well) were placed in the bottom well. They were separated by a 0.45-μM pore size membrane from an equal number of either LEW CD8 CD45RC^low, CD8 CD45RC^high, and CD4 T cells or cocultures of CD4 T cells with either CD8 CD45RC^low or CD8 CD45RC^high T cells (top well). Cells were stimulated with irradiated, T-cell depleted, BN splenocytes for 5 days. CD4 T-cell division was assessed by flow cytometry by gating on CD4 T cells. The percentage in each plot represents dividing T cells. Data are representative of 2 independent experiments.