Normal and Chronic Lymphocytic Leukemia Lymphocytes As Targets for Human Complement

Human lymphocytes are resistant to cytolytic effects of human complement in vitro. In order to study this phenomenon, the amount of human third component (C3) bound to lymphocytes from normal subjects and patients with chronic lymphocytic leukemia (CLL) was determined when complement was activated by reacting lymphocytes with anti-I antibody, anti-HLA-2 antisera, and rabbit anti-human lymphocyte antisera. C3 was quantitated by an anti-C3 consumption assay. Human C3 was bound to both normal and CLL lymphocytes in a dose-response fashion when the cells were exposed to human serum and the anti-lymphocyte antibodies. No quantitative differences were observed in binding of C3 to normal and CLL lymphocytes. Cytolytic effects of complement activation were measured by cell counting, dye exclusion, ⁵¹Cr release, release of ³H-thymidine labeled DNA, and the ability of the cells to incorporate ³H-thymidine and ³H-uridine into DNA and RNA.