Cytolysis of nucleated cells by complement: inhibition of membrane-transmethylation enhances cell death by C5b-9.

Inhibition of transmethylation, i.e., enzymatic transfer of methyl groups to phosphatidyl ethanolamine resulting in generation and translocation of phosphatidyl choline, enhances the killing of nucleated cells by complement. Furthermore, under complement attack, transmethylation measured as incorporation of [3H]methyl groups into phosphatidyl choline is enhanced, suggesting that transmethylation functions as a membrane defense mechanism either by increasing the phosphatidyl choline synthesis or by transducing a signal that might trigger another membrane repair process.