Complement-mediated cytolysis: quantification of B cell surface antigen molecules and role of cell cycle

Complement (C')-mediated cytolysis is currently used for the purging of autografts in autologous bone marrow transplantation (ABMT). However, a number of factors influencing the efficiency of lysis remain to be explored. In this report, firstly using a Scatchard analysis, the number of surface antigen molecules for CD19 and CD20 on 3 B cell lines has been quantified. This demonstrated that with CD20 a higher number of antigen molecules was required as compared to CD19 to produce an equally effective cytolysis. Secondly, the role of cell cycle has been investigated: cytolysis was not affected by cell phase. Moreover, CD19- and CD20-deficient cells escaping lysis displayed no difference in cell phase and possessed an identical growth pattern as controls.