Decreased activation status of naive CD4⁺ T cells cocultured with tolerized cells.

Naive CD4⁺ T cells cocultured with tolerized cells have a reduced activation status compared with control culture. Naive B6 CD45.1 CD4⁺ T cells were cultured with bm12 stimulators with or without the addition of tolerized B6 CD45.2 CD4⁺cells at a ratio of 3 naive cells to 1 tolerized cell. On day 5, cultures were analyzed by flow cytometry for parameters of T-cell activation. The contour plots of the culture without (panel A) and with (panel B) the addition of the tolerized cells demonstrate the percentage of naive and tolerized cells present in the culture. The naive cells are in the upper right portion of the plots and the tolerized cells in the upper left portion. The percentage of cells shown in each of the gates is shown. The second and third rows (panels C-D) illustrate the FSC and SSC histogram plots gated for the naive cells cultured alone, naive cells from the coculture, and tolerized cells from the coculture. The fourth and fifth rows (panels E-F) illustrate the percentage of cells positive for CD25 and L selectin (CD62L) expression in each of the gated populations.