Biosynthesis of C4 (Fourth Component of Complement) by Hybrids of C4-Deficient Guinea Pig Cells and HeLa Cells

Peritoneal exudate cells from guinea pigs homozygous for a genetic deficiency of the fourth component of complement (C4) were fused in vitro with a cell line of human origin (HeLa). The resulting hybrid cells, derived from cell lines each incapable of C4 synthesis by themselves, synthesized functionally active human C4.