LGL serum blocks Fas-induced apoptosis of normal activated T cells.

Panel on left shows spontaneous apoptosis. Panel in middle shows apoptosis of normal activated cells induced by anti-Fas mAb, with normal human serum added. Panel on right shows blocking of apoptosis by serum from an LGL leukemia patient. Similar results were obtained when studying sera from an additional 7 patients with LGL leukemia.