Cross reactivity studies with platinum group metal salts in platinum-sensitised rats.

Hooded Lister rats were sensitised to the halide salt of platinum ammonium tetrachloroplatinate(II)[(NH4)2PtCl4] in its conjugated form with ovalbumin. Sensitisation was achieved by intraperitoneal injection with Bordetella pertussis vaccine as adjuvant, followed 21 days later by a further injection in saline. The presence of specific anti-platinum IgE antibody was determined by passive cutaneous anaphylaxis (PCA) and radioallergosorbent test (RAST) using the platinum halide salt conjugated to a heterologous carrier. Sera exhibiting positive reactions were pooled and PCA tests performed on the titrated pooled sera with 3 conjugated platinum group metal salts, 5 platinum group metals in their free salt form and 6 platinum salts with differing ligands. PCA challenges with these compounds resulted in significant cross reactivity between ammonium tetrachloroplatinate(II), ammonium hexachloroplatinate(IV) and the conjugated tetrachloroplatinate. There was very limited cross reactivity with other platinum or platinum group metal salts in either free or conjugated forms. Furthermore, these results were confirmed by RAST inhibition studies.