Inactivator of the first component of human complement (C1INA). Enhancement of C1INA activity against C1s by acidic mucopolysaccharides.

Acidic mucopolysaccharides enhanced C1INA activity against C1s. The presence of heparin in the reaction mixture of C1INA and C1s markedly enhanced the inactivation of C1s by potentiating C1INA activity. Treatment of serum with C1s resulted in the inactivation of C4 hemolytic activity, but this inactivation of C4 by C1s was prevented by the presence of heparin presumably due to the enhancement of C1INA activity normally present in serum. The other acidic mucopolysaccharides, chondroitin sulfates A, B and C, were also effective on potentiating C1INA activity against C1s, but they were less active than heparin. The enhancement of C1INA activity by heparin was not observed in the reaction between C1INA and plasmin.