APOPTOSIS AND SECONDARY NECROSIS OF LYMPHOCYTES IN CULTURE

It has been reported that cultured peripheral B lymphocytes of chronic lymphocytic leukemia (B-CLL) patients show a high degree of apoptosis (programmed cell death). Till now, no data exist about the occurrence of in vitro apoptosis of normal B and T cells, We measured the amount of apoptosis and secondary necrosis (type 2 necrosis) in B-CLL lympho cytes and in normal peripheral B and T lymphocytes in culture, Observa tions were made on B-CLL lymphocytes and on normal B and T cells purif ied by immunomagnetic cell sorting, Apoptosis and secondary necrosis w ere measured using a recently described sensitive flow-cytometric assa y, probing simultaneously for cell surface exposure of phosphatidylser ine with the use of FITC-labeled annexin-V and for cell membrane integ rity as demonstrated by the exclusion of propidium iodide, The degree of in vitro apoptosis and secondary necrosis of normal B cells appears to be higher than that of normal T cells, and even higher than that o f B-CLL cells, The results indicate that cultured mature circulating n ormal B lymphocytes exhibit a higher cell death rate than normal T cel ls and B-CLL lymphocytes.