Aggregation of equine platelets by Onchocerca cervicalis collagen

Abstract

The arachidonic acid pathway plays an important role in many inflammatory reactions. Current evidence suggests that platelets can play a central part in host inflammation. Since microfilariae are mobilized into the bloodstream following diethylcarbamazine (DEC) treatment, we have studied the effects of Onchocerca cervicalis cuticle preparations on equine platelet aggregation. The authors have found that O cervicalis cuticular preparations can induce platelet aggregation in vitro. Furthermore, this activity was abrogated by treatment with collagenase and not hyaluronidase, elastase, or alpha-chymotrypsin. When this evidence is viewed collectively with the evidence for in vivo parasite cuticular damage following DEC treatment, it becomes entirely plausible that the cuticular damage may indeed reveal a platelet-reactive surface, thus permitting platelet-parasite binding to occur. This binding would result in platelet aggregation and the generation and release of platelet-derived arachidonate metabolites. These metabolites may play a very critical role in the development of the described pathologic sequelae observed following DEC treatment. Field studies using cyclooxygenase and lipoxygenase inhibitors might therefore be very efficacious in decreasing the frequency of side effects due to DEC or other potentially effective drug regimens.