A preparation of Fc fragment of normal mouse IgG1 for production of rabbit anti mouse IgG1 serum.

Ascitic fluid globulins obtained by peritoneal irritation from normal CBA mice were digested with papain, and the digests were examined by gradient chromatography on CM cellulose. The classical three peaks of OD280 found by Porter with papain digests of rabbit IgG were obtained. Fraction II contained material which reacted in immunodiffusion against mouse anti-IgG. The ascending part of this peak reacted against anti-IgG1 and not against anti-TgG2 reacting material appearing at detectable levels in the descending part of this peak. A pool from the ascending part of this peak, containing Fc of IgG1 and not visibly contaminated with Fc of IgG2, was injected into rabbits. The resulting antisera were free enough of anti-IgG2 to be effective in removing IgG1 from alloantibody-containing globulins without appreciable loss of antibodies of IgG2 class, thus allowing the complement-dependent IgG2-class antibodies full expression of their titer, without competition by Ig1 class antibodies. Chromatography of native mouse globulin did not produce a similar degree of separation of Ig1 from IgG2.