Differential diagnosis of kidney transplant rejection and cyclosporin/tacrolimus nephropathy using urine cytology.

A total of 9000 urine samples from 69 kidney transplant recipients were studied for differential diagnoses of transplant rejection and cyclosporin/tacrolimus toxicity. New-Sternheimer and Papanicolaou staining were used to differentiate cells in urine. We also employed an immunocytochemical technique for further identification of exfoliated cells. With New-Sternheimer and Papanicolaou staining, the predominance of proximal tubular cells was useful to differentiate cyclosporin/tacrolimus toxicity from acute rejection in cases of increased serum creatinine level. During rejection episodes, an increased number of mononuclear cells and renal epithelial cells were found. Immunocytochemical analysis showed a significant increase of CD2-, CD4- CD8-, CD25- and HLA-DR-positive cells with rejection. However, there was no relationship between Banff criteria rejection grade and the increase of mononuclear cells.