INTERFERENCE OF PROPAMIDINE WITH BINDING OF 5TH COMPONENT OF COMPLEMENT TO SURFACE-FIXED C3B, AND WITH C5 ACTIVATION

  • 1 January 1979
    • journal article
    • research article
    • Vol. 36  (1) , 139-143
Abstract
The effects of propamidine and their dose dependency on utilization of the [guinea pig and human] 3rd [C3] and 5th [C5] complement components in immune hemolysis of sheep red cell were compared. While C3 utilization was not distrubed, that of C5 was markedly inhibited by propamidine in concentrations as low as 0.5 mM. Binding of C5 to surface-fixed C3b [b fragment of C3] and cleavage of C5 by convertases C42 and C3bBb were inhibited in the presence of propamidine. C3 cleavage by these enzymes and C5 cleavage by the cobra venom factor-supported convertase CFVBb were not significantly reduced; a general convertase inhibiting effect of propamidine was ruled out. The effect on utilization of C5 was the result of interference with binding of C5 to C3b and impairment of its accessibility to the convertases. The role of surface-fixed C3b in C5 activation proposed earlier was supported.