Studies on the Alternative Pathway in Systemic Lupus Erythematosus Using Rabbit Red Blood Cells

Methods of measuring the activity of the total alternative complement pathway, properdin and Factor B with rabbit red blood cells(RaRBC) were examined. The following results were obtained.1) 0.03M EGTA-GVB permitted activation of the alternative complement pathway without activation of the classical complement pathway.2) RaRBC were hemolysed by C4/C2 depleted serum as well as by normal serum. RaRBC were not hemolysed by inulin or zymosan treated serum.3) The activity of the total alternative complement pathway was measured with 50% hemolysis of RaRBC in EGTA-GVB, designated as ACH50.4) The activity of properdin or Factor B was measured with RaRBC and normal fresh human serum deficient in properdin(RP) or deficient in Factor B(RB).