Immunological responses to complex salts of platinum. I. Specific IgE antibody production in the rat

Ammonium tetrachloroplatinate II ([NH4]2 PtCl4) was used in free and conjugated forms with ovalbumin in an attempt to elicit specific antibody directed against either the free platinum (Pt) salt or the platinum moiety of ovalbumin-Pt conjugates in the hooded Lister rat. Immunization with free Pt salt via intraperitoneal, intramuscular, intradermal, subcutaneous, intratracheal and footpad routes over a wide range of doses (1 microgram-1 mg) employing both B. pertussis and/or aluminium hydroxide gel as adjuvants failed to induce specific IgE antibody, either primary or secondary, as shown by direct skin, PCA test or RAST. Conjugation of (NH4)2 PtCl4 with ovalbumin produced conjugates, with between two and 10 haptenic Pt groups per ovalbumin molecule, capable of inducing IgE antibody directed against the Pt moiety as determined by heterologous PCA challenge, where carrier cross-reactivity was excluded, and by specific RAST, confirmed by RAST inhibition.