The specificity of skin-sensitizing antibodies in the guinea-pig.

In this paper the specificity of the skin-reactive guinea-pig immunoglobulin in the homologous PCA test has been reconsidered. Extensive purification of this immunoglobulin by chromatographic methods results in the isolation of a small fraction of medium speed immunoglobulins that contains all skin reactivity. No correlation could be found with the 7S immunoglobulins IgGγ1 and Igγ1A, suggesting a separate class of biologically active immunoglobulins. The PCA active antibody belongs to either an IgG subclass or is a heat stable homocytotropic antibody. Rabbit and chicken antisera against isolated fractions of guinea-pig immunoglobulins show the existence of 7S subclasses. Some suggestions for a revised nomenclature are given.