The chemical nature of the funnel-web spider venom inhibitor found in rat plasma.

Strong evidence has been obtained that the funnel-web spider venom inhibitor, previously found to occur naturally in the blood of rats, is at least partly immunoglobulin in composition. However, the results of chromatographic and immunological studies, including the use of specific antisera, indicate that this inhibitor is not a single chemical entity and apparently resides within more than one immunoglobulin class. In addition, it was observed that challenge of rats with Atrax venom substantially increased the venom-inhibiting powers of their blood and that these powers were located in the same plasma fractions as in unchallenged rats.