Cytotoxic effects of eosinophils on renal proximal tubular epithelial cells: implications for renal allograft rejection.

Eosinophils are inflammatory cells that actively participate in the defense against large, multicellular parasites. Eosinophils are also a prominent component in the inflammatory infiltrates seen in acute allograft rejection. Their role in that process, however, remains obscure. In this study we examined in vitro the direct cytotoxicity of eosinophils against renal proximal tubular epithelial cells (PTEC) in the presence or absence of antibody and complement. Eosinophils were able to attach to the PTEC surface in both circumstances, i.e., irrespective of opsonization, or other mediation by humoral factors. The release of eosinophil granule contents (including their characteristic crystalloids) on the target cell surface and resulting PTEC injury occurred also irrespective of the presence or absence of opsonization. Thus, based on these results, the potential of direct cytotoxicity of eosinophils for PTEC exists, particularly in situations where both of these cell types are 'activated'.