To assess the capacity of transitional cells to synthesize the release polymeric immunoglobulin receptor (pIg-R) in bladder carcinoma, we studied the localization of pIg-R in normal and tumor tissues and measured the levels of secretory component (SC) either in the free form or bound to Ig (S-IgA, S-IgM) in the serum and urine of 56 patients with transitional-cell carcinoma (TCC) of the bladder. In the normal bladder mucosa, pIg-R was localized in the cytoplasm and plasma membranes of the superficial cells and on all epithelial cell membranes. In TCC cases, 65% of those studied expressed pIg-R. A marked heterogeneity in pIg-R staining was observed in some tumors. Although a better expression of pIg-R in tumors with a well-preserved epithelial architecture was observed, no correlation was found between pIg-R expression and the grade or stage of the tumors in the patients under study. Three groups were established: (1) in TCC with no complications, serum levels of free SC and S-IgA were significantly increased; (2) in TCC with urinary infections (UI), serum levels of free SC and S-IgA were significantly higher than control values but lay within the same range observed in TCC with no complications and rates of urinary excretion of SC were significantly higher than those in normal subjects; (3) in TCC without UI but with hepatic disorders [high gamma-glutamyl transferase (GGT) activity], there was a correlation between serum S-IgA levels and GGT activity (r = 0.5, P less than 0.005) and serum SC levels were significantly higher than those observed in the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)