Histochemical observation of F 1881 binding protein in human benign prostatic hypertrophy

A 3-carboxymethyloxime conjugate of R 1881 was conjugated with bovine serum albumin and reacted with fluorescein isothiocyanate. Tissue sections from patients with benign prostatic hypertrophy were incubated with this compound. Fluorescence was observed in the cytoplasm of gland cells, although both positive and negative cells were distributed evenly in some areas. Neither the stroma nor the nuclei of epithelial cells were fluorescent. Preincubation with a 20 fold molar excess of R 1881-carboxymethyloxime-bovine serum albumin, 1 microM of R 1881, or 1 microM of triamcinolone acetonide diminished fluorescence of the section. Bovine serum albumin conjugated with fluorescein isothiocyanate did not stain the section. Therefore, the fluorescence observed in the sections seems to be attributable to the high affinity binding of R 1881. The intensity and number of fluorescent cells and the R 1881 binding estimated by a biochemical method were well correlated.