Apoptosis of T1 B lymphocytes on CD38 crosslinking. (A) T1 B cells, obtained as in Figure 2, were preincubated with 8-Br-cADPR or medium for 30 minutes, stimulated as indicated, and 24 hours later, permeabilized and stained with PI. The histograms show the content of DNA for each condition. The numbers represent the percentage of T1 B cell in SubG₀ region. (B) T1 B cells were activated as above and harvested and stained with annexin V and PI. Numbers indicate the percentage of T1 B cells in each region. The dot plots are representative from 3 independent experiments with similar results.