WT1 immunoenzyme staining using SurePath™ processed urine cytology helps to detect kidney disease

Objectives Damage and detachment of podocytes and loss into the urine have been implicated in the progression of kidney diseases. The purpose of this study was to investigate the potential role of urine cytology based on SurePath™ combined with immunoenzyme staining using Wilms’ tumour 1 (WT1) antibody as a podocyte marker in the discrimination of normality and non‐renal urinary tract disease from kidney disease. Methods Sixty‐six patients with kidney disease, 45 patients with lower urinary tract disease and 30 healthy volunteers were examined. Urine cytology slides were prepared using the SurePath method and immunoenzyme stained with WT1 antibody, and the number of WT1‐positive cells was counted. Results In kidney disease, WT1‐positive cells were found in 33 (50%) of 66 samples. No WT1‐positive cells were found in 45 patients with lower urinary tract disease or in 30 healthy volunteers. The positive rates for WT1 varied with disease type, but not significantly: immunoglobulin A (IgA) nephropathy, (14/23); membranous glomerulonephritis, (4/10); Henoch–Schönlein purpura nephritis, (3/5); diabetic glomerulopathy, (5/5); minor glomerular abnormality/minimal change nephrotic syndrome (0/4). Conclusions The results suggest that WT1 immunoenzyme staining of urine cytology can be used to detect some types of kidney disease. Immunoenzyme staining for WT1 on Surepath TM processed urine cytology samples showed WT1 positive podocytes in 50% of the patients with kidney disease studied. There was no positive staining in urine from those with lower urinary tract disease or healthy volunteers. WT1 staining, which is cytoplasmic in these Surepath preparations, could be a low cost, easy to perform method for the detection of some types of kidney disease.