Rosette formation of human erythrocytes on cultured cells of tumour origin and activation of complement by cell membrane

Abstract

WHEN some cultured cells (OAT cells¹, a cultured cell line from lung cancer) were treated with normal fresh human, guinea pig or rabbit serum and mixed with human erythrocytes (HuE), rosette formation of HuE occurred around the treated cells. We thought initially that the phenomenon might involve natural antibodies and complement because antigen–antibody–complement complexes are known to adhere to HuE by the phenomenon of immune adherence². This possibility was excluded by the finding that rosette formation of HuE around serum-treated cultured cells occurred in the absence of Ca²⁺, since Ca²⁺ is known to be essential for the reaction of the first component of complement (C1). That the alternative pathway of complement activation³ (Properdin system) might underlie the generation of rosette-forming ability was suggested by the demonstration that Mg²⁺ was an essential requirement.