Peripheral nerve CR1 limit complement-mediated haemolysis

CR1 were purified from sciatic nerve extracts by monoclonal antibody affinity chromatography. The effect of CR1 on complement-mediated haemolysis was studied by adding purified CR1 to a mixture of human serum as source of complement and sheep erythrocytes sensitized with rabbit IgG. A dose-dependent inhibition of the haemolysis occurred. There was no effect on the haemolysis when phosphate-buffered saline, elution buffer or run-through fraction not containing CR1 was added. Addition of a polyclonal anti-CR1 antibody to purified CR1 suppressed the inhibiting activity, strongly indicating that peripheral nerve CR1 inhibit complement-mediated haemolysis. This may be of great importance in vivo since CR1 present on the Schwann cell membrane may prevent the formation of terminal lytic complexes.