The proapoptotic effect of TC-A is more pronounced in B cells than in T cells of B-CLL patients. B cells (□) and T cells (▦) of 48 B-CLL patients were left untreated or treated with 1 μM or 2.5 μM TC-A for 24 hours. Exposure of phosphatidylserine as a specific marker for apoptosis was determined by flow cytometry using the annexin V—FITC binding assay. Results are shown as the differences of TC-A—induced apoptosis minus spontaneous apoptosis. Box plots represent median values and 50% of the data, and whiskers represent the interquartile ranges.