Serologic Specificity of Immunoconglutinin Associated with Infectious Anemia of Rats and Its Role in Nonspecific Acquired Resistance

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Abstract
Nonspecific resistance was induced in rats infected with filterable agent of rat infectious anemia (RIA) and in mice infected with Plasmodium chabaudi by injections of globulin of rats hyperimmunized by infections of Babesia rodhaini. The resistance was manifested by anemia that appeared earlier in passively immunized animals than it did in controls. In the mice the anemia was accompanied by reductions in parasitemia. Survival of the immunized animals was enhanced. The 19S fraction of the globulin contained immunoconglutinin (IK) activity which had a specificity for fixed C3 [complement component 3] and was 2-mercaptoethanol sensitive. The 7S fraction contained antibody [Ab] to soluble serum antigen [Ag] (ABSA). Infected animals given the IK fraction had parasitemia and/or anemia and mortality that did not differ from that seen in controls. Those given the ABSA fraction had early reduction in parasitemia with anemia and enhanced survival. The protection and anemia were more pronounced in those animals given IK and ABSA. Fluorescein-conjugated IK and ABSA reacted with blood films and spleen-impression slides of rats with acute RIA and babesiosis and of mice with acute P. chabaudi malaria. Complexes of soluble serum Ag and ABSA apparently had fixed C and became bound to blood cells of the circulation and those sequestered and phagocytized in the spleen. The conglutinating action of IK may have enhanced the removal of complex-coated cells and parasites from the circulation. Functionally, IK is Ab to complexes of Ag, Ab and C it may have contributed to protection by reducing the amount of pathogenic immune complexes in the blood.