Evaluation of Mechanisms of Leptospiral Hemolytic Anemia

Abstract

SUMMARY Six groups of 4 to 8 sheep each were inoculated with Leptospira pomona to study the mechanisms of leptospiral hemolytic anemia. Sheep usually became febrile within 5 or 6 days and hemolytic anemia was observed frequently during the early clinical course of the disease. However, constant relationship between the time of occurrence of anemia and appearance of detectable circulating leptospiral agglutinins was not observed. This observation and the failure to detect leptospiral antigens on the erythrocytes of anemic sheep by hemagglutination or passive lysis tests or to detect leptospiral hemolysin in the plasma of anemic sheep did not support some previous hypotheses on the mechanism of hemolysis. In addition, although an incomplete antierythrocyte antibody was detected in the serum of affected sheep by antiglobulin tests, the antibody seemed to be related to blood group reactivity rather than to an autoimmune phenomenon, the latter having been suggested as another mechanism in the pathogenesis of the anemia. However, cold reactive hemagglutinins were detected in the plasma of anemic sheep, indicating that this antibody may be involved in the lytic phenomenon in the intact animal.