Anti-leishmania activity of normal animal sera

The growth inhibition activity of normal human, dog, rabbit, guinea pig, rat, sheep, cat, mouse and chicken sera was quantified against Leishmania enriettii and Leishmania tropica. The pattern of anti-L. enriettii activity of various animal sera was somewhat different from that observed in L. tropica. Against L. enriettii, mouse serum was inactive, and against L. tropica rat and mouse sera were inactive. All the other animal sera tested had growth inhibition activity on both leishmanias. This growth-inhibiting factor was found to be heat-labile, complement dependent, adsorbable by the specific organism and non-dialyzable. Only the first few subcultures of leishmania were affected by the active sera.