Induction of apoptosis of normal polymorphonuclear neutrophils (PMN) with serum from patients with LGL leukemia.

PMN were purified from healthy donors and incubated for 1 day in RPMI medium with 10% normal human serum in the absence (Cntl) and presence of anti-Fas monoclonal antibody (MAb) CH11 (100 ng/mL) or with serum from patients with LGL leukemia (A-I). Apoptotic cells were examined with use of both a Diff-Quik Stain Set and flow cytometry. Apoptosis induced by serum from patients with LGL leukemia was inhibited with a blocking anti-Fas MAb (ZB4). In contrast, no inhibition of apoptosis induced by serum from patients was observed with the addition of an irrelevant, IgG1-isotype control MAb. Data represent results of 3 separate experiments.