Guinea-pig reaginic antibody. I. Isolation and purification of an antibody protein with characteristics of IgE.

The methods for isolation and purification of a guinea-pig serum protein with homocytotropic antibody activity and characteristics of IgE are described. By precipitation in the equivalence zone or immunoadsorption and chromatography on DEAE-cellulose, we isolated an homocytotropic antibody, that was not able to give a precipitin line when it was reacted directly with the antigen. It was capable of sensitizing guinea-pig skin for PCA after a latent period of 24–48 hours but not after 3 hours; it was sensitive to treatment with mercaptoethanol. It had antigenic determinants present in the other guinea-pig immunoglobulins and particular antigenic determinants. All these properties make us believe that this protein belongs to an immunoglobulin different from γ1 and similar to the reaginic antibody (IgE) described in other species.