A 24-kDa collagenase from Gymnorhynchus gigas elicits rat ileum hyperreactivity and is a target of humoral responses in mice previously given a single oral dose of parasite extract.

Fish declared fit to be eaten may contain plerocercoids (larvae) of the fish cestode Gymnorhynchus gigas. We showed previously that crude G. gigas larval extract given in a once-only oral dose to either mice or rats induces parasite-specific immediate-type responses and that this extract evokes increased contractile activity in normal rat ileums. We show here that a 24-kDa collagenase (24-kCol), purified from the crude extract is (1) a target of both local (intestinal) and systemic IgE responses in mice sensitized by oral G. gigas and (2) elicits considerable changes in rat ileum contractility. Exposure of rat ileum segments once to 7 microg 24-kCol significantly increased tone and amplitude, but not frequency, of contractions compared with control recordings. In all, these studies have indicated 24-kCol, an abundantly produced protein of G. gigas larvae, to be a participant in potentially serious/adverse intestinal responses in both mice and rats. Such responses are very likely to occur in "sensitized" humans also.