Properties of a cold hemagglutin in associated with leptospiral hemolytic anemia of sheep.

The cold hemagglutinin which appears after leptospiral infection of sheep was isolated consistently from the plasma by absorption to autologous erythrocyte stroma at 4 C and subsequent elution at 25 C. Immunoelectrophoretic tests disclosed that the purified preparations consisted primarily of a single detectable component with the electrophoretic, positional, and antigenic characteristics of ovine immunoglobulin M. The properties of the cold hemagglutinin included a rapid sedimentation rate, elution in the leading peak from G-200 Sephadex, high anionic-binding capacity, and rapid electrophoretic mobility. Thus, these methods also supported the identification of the cold hemagglutinin as a homogeneous protein with properties like immunoglobulin M. The occurrence of the cold hemagglutinin after the phase of leptospiremia and concurrent to the onset of hemolytic anemia suggests that this antibody may play a significant role in the genesis of leptospiral acquired hemolytic anemia.