FIG. 4.

Induction of apoptosis in CD8⁺ and CD4⁺ T cells by rLTB, but not by the non-GM₁-binding mutant rLTB/G33D, as detected by DNA ploidy analysis. Representative DNA histograms from CD8-enriched (73% CD8⁺, 6% CD4⁺, and 20% Ly5⁺) (top row) and CD4-enriched (83% CD4⁺, 3% CD8⁺, and 12% Ly5⁺) (bottom row) spleen cells after treatment with 10 μg of rLTB or rLTB/G33D per ml for 24 h are shown. DNA ploidy analysis was done as described in Materials and Methods. The percentages of hypodiploid cells (left to right) were 51, 14, and 10% for CD8 T cells and 28, 11, and 12% for CD4 T cells. See Table 2 for average results from four experiments.