Innate and Acquired Agglutinins in Ducks to the Malaria Parasite Plasmodium lophurae.

Abstract

Summary

Erythrocyte-free suspensions of Plasmodium lophurae were agglutinated to a variable degree by the fresh plasma of ducks which had not been infected by this parasite. The agglutinating activity of the plasma was in general higher in older ducks than in young ducklings. It was rarely evident beyond a 1:4 dilution of the plasma, and was fully removed by heating the plasma for one-half hour at 55-56°C followed by centrifugation to remove the precipitate which formed. In infected ducks 3 months of age or older these heat-labile agglutinins generally decreased as the infection progressed, except in individuals which exhibited a strong innate resistance to the parasites. The heat-labile agglutinins disappeared completely at the peak of a severe infection. Heat-stable agglutinins appeared in the plasma of most of the infected birds. These, unlike the heat-labile agglutinins, were not demonstrable in undiluted plasma but often were active in plasma diluted as far as 1:1000. In ducklings infected when they were one month old or younger, heat-stable agglutinins did not appear. As in severely infected older ducks, the heat-labile agglutinins vanished at the peak of the infection. If such ducklings were saved from death by treatment with quinine the heat-labile agglutinins reappeared to a varying degree. Relapses, like initial infections, were accompanied by a lack of heat-labile agglutinins.