Immunogenicity of p-phenetidine, 2-hydroxy-p-phenetidine and their protein conjugates in guinea pigs, rabbits and man.

Guinea pigs were sensitized by p-phenetidine (PT), 2-hydroxy-p-phenetidine (HPT) as well as by conjugates prepared by reacting PT and HPT with proteins in vitro. Sensitization was evaluated by delayed skin reactivity and in vitro antigen-induced lymphocyte proleferation. HPT and HPT-protein conjugates were found to be the most effective sensitizing agents. Reaginic antibodies could be raised in both guinea pigs and rabbits by immunizing with PT- and HPT-protein conjugates but not by PT and HPT alone: these PCA antibodies showed strong cross-reactivity and could be elicited equally well with either the PT- or HPT-protein derivatives. By contrast, no precipitating antibodies could be raised in either species even after repeated immunizations over a period of 4 months. Peripheral blood lymphocytes, from a few patients who gave a positive patch test with PT, could be stiumlated in vitro with phenacetin and to a lesser degree with PT and with a HPT-derivative of human serum albumin.