Studies on Immune Factors Occurring in Sera of Chickens Against the Crithidia Stage of Trypanosoma Cruzi

It has been shown by immunologic methods that fowl sera contain at least two factors against the crithidia of Trypanosoma cruzi: a heat-stable factor which is in all probability a strongly agglutinating and sensitizing antibody, and a heat labile factor which is probably complement. The antibody was present in the sera of all mature normal birds tested, it was transmitted to the yolk and thence to the blood of the embryo, greatly reduced or lost after hatching and regained upon immunologic maturation. Birds hatched and reared under germ-free conditions had the antibody in their sera until shortly after hatching; however, after losing it, it did not reappear. The heat labile, lytic factor was present in the sera of birds regardless of environmental influence. It is concluded that the agglutinating factor (antibody) is due to response to a cross reacting antigen possibly present in a common contaminant of fowls.