Spontaneous formation of immunogenic conjugates by ortho- and para-aminophenol

Ortho-aminophenol (OAP) and para-aminophenol (PAP) react readily with proteins at alkaline pH giving rise to conjugates capable to induce hapten specific antibodies in rabbits. PAP and OAP immunological systems do not cross react with each other, but both anti-PAP and anti-OAP serum give intense cross passive hemagglutination reactions with hydroquinone and pyrocatechin conjugates prepared by the same procedure. PAP immunological system does not cross react with various systems of the "para" group in which the conjugates were prepared by diazotization. PAP proved unable to induce formation of specific antibodies when inoculated in Freund adjuvant into rabbits and both PAP and OAP were unable to sensitize erythrocytes by incubation at alkaline pH. The findings are discussed in the light of data from literature showing that some drugs with amino aromatic structure are transformed in the body into compounds with PAP or OAP structure which might be able to form immunogenic conjugates with autologous proteins in vivo.