Nonspecific activation of complement factor 5 by isolated Dermacentor andersoni salivary antigens.

Salivary gland extracts from feeding Dermacentor andersoni ticks contain an activity that activated both rabbit and human complement to produce inflammatory cell chemotactic activity. Purified salivary antigens (SGA), isolated from the glands of female ticks with anti-saliva immunoglobulins from tick-resistant rabbits, also induced chemotactin generation. It has been demonstrated previously that the intradermal injection of such SGA into normal animals induces nonspecific inflammatory reactions that mimic the responses accompanying tick feeding on normal animals. The chemotactic activity generated in serum by SGA was mediated either directly or indirectly by C5, as it could be abrogated by antisera directed against C5 but not by anti-C3 sera. That the in vitro generation of C5 by tick salivary proteins has relevance to tick feeding is suggested by the fact that many of the host inflammatory responses elicited by ixodid tick feeding also are effects known to be elicited by C5.