Receptor sites for complement and for immune complexes on human nonhemopoietic tumor cells

Abstract

Tumor cells in primary cultures derived from 11 untreated nonhemopoietic cancer patients were reacted with specifically coated sheep erythrocytes. Rosette formation between tumor and indicator cells was assessed. Of the primary cultures, 8 reacted positively with Ig[immunoglobulin]G-coated (EA[erythrocyte-antibody]IgG) and with IgM-human complement [C] coated (EAIgMC or EAIgMC 4,3) sheep erythrocytes. EAIgG rosette formation in positive cultures ranged from 25-85%, and for EAIgMC/EAIgMC 4,3 reactivity ranged between 22-95%. Rosette formation with E (uncoated) and EAIgM was negligible. Human nonhemopoietic tumor cells may carry on their surface receptor sites for an IgG component of immune complexes and for human C. These receptor sites may be important in the host-tumor relationship.