Rat 7S immunoglobulins: characterization of gamma-2- and gamma-1-anti-haptens antibodies.

Two antigenically distinct populations of rat antibodies to the 2,4-dinitrophenyl group (DNP) have been isolated by chromatography on DEAE-cellulose and named fraction 1 and fraction 3. Both fraction 1 and fraction 3 had sedimentation coefficients of 6.9S, similar hexosamine contents (1.04 and 0.89 per cent) and electrophoretic mobilities similar to the γ- and γ-immunoglobulins of guinea-pigs and mice. Fraction 1 consisted of two distinct antibody populations with very similar mobilities. Only fraction 1 was able to sensitize homologous rat skin for passive cutaneous anaphylaxis (PCA). Both preparations were active in haemolysis of passively sensitized sheep red cells in the presence of complement, and fraction 3 was more lytic than fraction 1. In other tests such as PCA in mice, passive haemagglutination and precipitation in gel the behaviour of the two fractions was similar. Fraction 3 is probably the immunoglobulin designated γA in earlier reports. The results indicate that fraction 1 and fraction 3 correspond to the 7S γ- and 7S γ-immunoglobulins of guinea-pigs and mice, except for their behaviour in homologous PCA and in passive haemolysis, and that fraction 1 and fraction 3 are rat 7S γ- and 7S γ-immunoglobulins, respectively.