RENAL-ALLOGRAFT REJECTION - IN-SITU DEMONSTRATION OF CYTOTOXIC INTRATUBULAR CELLS

A nonisotopic in situ hybridization method to detect perforin mRNA was developed in cytospin preparations of IL-2-stimulated normal human ly mphocytes and applied to formalin-fixed acutely rejected renal transpl ant material. individual cells expressing perforin mRNA were localized in severely damaged tubular areas, and a number of these cells appear ed to be located inside the tubular basement membrane in close associa tion with tubular epithelial cells. Immunoperoxidase staining in aceto ne-fixed cryostat sections of acutely rejected kidney confirmed that a considerable proportion of infiltrating cells was CD8+; many of these were in an intratubular location. In addition, perforin protein was i dentified in individual cells in similar locations to perforin mRNA-po sitive cells. Again, some intratubular cells were identified. Our find ings illustrate that these cells can be fully activated with definite cytotoxic potential. Previously we have demonstrated that T lymphocyte s proliferate within the tubular compartment during tubulitis, a chara cteristic condition in acute renal allograft rejection, and that there is associated tubular epithelial cell proliferation. In this study we think that we have further clarified the consequences of invasion of tubules by lymphoid cells. Our in situ hybridization method is rapid a nd convenient and may be applied to archival material.