COMPLEMENT DEPLETION IN RATS INFECTED WITH FASCIOLA-HEPATICA - IN-VIVO AND IN-VITRO STUDIES

The action of Fasciola hepatica on rat complement was evaluated by mea suring the haemolytic activity. Extracts from metacercariae and eggs a nd the excretory and secretory products of adult flukes reduced the cl assical pathway of complement-mediated lysis by normal rat sera in a p rotein dose-dependent manner. Whole metacercariae produced the same ef fect. In vitro incubation of newly excysted juveniles and intact eggs with normal rat serum had no detectable effect on serum complement act ivity by either the alternative or classical pathway. During the cours e of rat fasciolosis a depletion in the classical pathway of complemen t-mediated lysis was demonstrated particularly 6-9 weeks post-infectio n; the alternative pathway of complement-mediated lysis was not affect ed.