Heterophile antibodies in the serum of children with nephrotic syndrome.

Serum of children with the nephrotic syndrome contained high titers of a (19S) IgM antibody against sheep, horse, guinea pig, rat, and rabbit red blood cells but not against cow red blood cells. There was high correlation between high titers of antisheep antibodies and active nephrotic syndrome in the children with minimal change nephrotic syndrome. The antibody differed from the Paul-Bunnell antibody found in patients with infectious mononucleosis and from the anti-Forssman, Hangautziu-Deicher antibody found in patients with horse serum sickness. Rabbit red blood cells completely absorbed the antibody, but horse or guinea pig red blood cells removed only the anti-Forssman activity.