T-cell-dependent popliteal lymph node reactions to platinum compounds in mice

The requirements for sensitization to complex salts of platinum were investigated in a mouse model by means of the popliteal lymph node (PLN) assay. A single subcutaneous injection of dissolved hexachloroplatinates without adjuvant induced a vigorous primary immune reaction in the draining PLN. Dose-dependent lymph node activation was determined by an increase in both PLN weight and cellularity. In C57BL/6 mice, peak reactions were obtained around day 6 after administration of 90-180 nmol Na2[PtCl6] or (NH4)2[PtCl6] per animal. Mice primed to [PtCl6]2- mounted an enhanced response upon local restimulation with suboptimal doses of the same but not unrelated compounds, indicating a specific secondary response. T cells were required to elicit PLN reactions to [PtCl6]2-, because athymic nude mice completely failed to respond, in contrast to their +/nu littermates. Differences between various inbred strains of mice revealed that Pt-induced PLN responses are genetically controlled. Moreover, the immunogenicity of Pt salts in mice is not confined to hexachloroplatinates, but other compounds, such as the antineoplastic agent cis-dichlorodiamine platinum, are able to induce comparable PLN reactions.