Correlation of the Fas-sensitivity of CD4⁺and CD8⁺ cells of B-CLL patients with the inversion of the CD4⁺/CD8⁺ ratio. Experimental data from both T-cell subsets of B-CLL patients (see Fig 2A) were grouped into two catusing a CD4⁺/CD8⁺ ratio of 1.0 in PBMC of B-CLL patients as cutoff level (< 1.0: n = 17; >1.0: n = 13). The boxes represent the increase in the percentages of apoptotic cells after 24-hour incubation with CH11 MoAb (250 ng/mL). Results of the statistical analysis CD4⁺ cells: < 1.0 versus >1.0 (P < .03), CD8⁺ cells: < 1.0 versus >1.0 (P > .8).