The inhibition of complement-dependent hemolysis by liposomes containing cerebroside sulfate

Cerebroside sulfate (CGS) was found to be capable of inhibiting complement- dependent hemolysis. The activity dependence of CGS-containing liposomes on their composition was studied. Mixtures of CGS with phosphatidylethanolami ne, phosphatidylserine, sphingomyelin from cattle brain, cerebroside from c attle spinal cord (CG), and egg yolk phosphatidylcholine (ePC) were investi gated. In the case of binary CGS/ePC mixtures, the antihemolytic activity v aried nonlinearly with an increase in the mass part of CGS: it sharply incr eased with an increase in the CGS part from 0.3 to 0.5 and decreased by 20- 30% of the maximum value with an increase in the CGS part from 0.9 to 1. On the basis of these experiments, the optimum distance between the charged g roups of CGS was estimated to be 0.92-1.6 nm. In the ternary compositions o f 4 : 3 : 3 CGS/ePC/polar lipid, only CG increased the activity of liposome s as compared to that of liposomes from the 4 : 6 CGS/ePC. The preliminary incubation of CGS-containing liposomes with complement decreased hemolysis more effectively than incubation with other components of the hemolytic sys tem. This suggests that the interaction of CGS-containing liposomes with th e complement proteins is responsible for their antihemolytic activity.