Secretory immunity of the prostate gland.

We investigated the immune response of the prostate to bacteriuria and bacterial prostatitis. In men with no histories of urinary tract infection the ratio of IgG:IgA in the expressed prostatic secretions was less than in the serum; most of the IgA was in the secretory form, and immunoglobulin directed against bacterial antigen was almost never detectable. In contrast antibacterial IgG and IgA were usually detectable in the expressed prostatic secretions of men with recent bacteriuria or bacterial prostatitis. The results of quantitative assays for antibacterial immunoglobulin in the expressed prostatic secretions and serum were consistent with local synthesis and secretion of antibacterial IgA. The immune response of the prostate to bacterial infection has the characteristics of secretory immunity.