Identification of renal tubular epithelial cells in urine with immunofluorescence

Rabbits were immunized with human kidney homogenate. The rabbit sera, after absorption with human liver homogenate, showed antibody activity against human kidney, renal pelvis and urinary bladder. The sera were then absorbed with human renal pelvis and urinary bladder mucosa and subsequently showed no antibody activity against urinary bladder or renal pelvis. Immunofluorescence examinations showed fluorescing cells in kidney tubules, but not elsewhere. The finally absorbed antihuman kidney sera were used for indirect immunofluorescence examination of urinary sediments from patients with renal disease. Phase contrast microscopy was used simultaneously. Fluorescence was found in cells which in phase contrast microscopy were judged to be renal tubular cells. Fluorescing cells were often found in casts, but free cells were also seen. Immunofluorescence may thus provide a means of identifying renal tubular cells in urine.