Activation of human complement by crude and purified antigens from Echinococcus granulosus.

Hydatid cyst fluid of Echinococcus granulosus was found to interact with human complement. This interaction resulted in the depletion of hemolytic complement in normal serum and in the electrophoretic conversion of C3 and factor B. The results provided evidence of an activation of complement via the alternative pathway when hydatid cyst fluid was used in the mixtures. Also purified hydatid antigen preparations were found to interact with complement in vitro; this interaction resulted in the consumption of complement not only via the alternative pathway, but also via the classical pathway.