The characterization of bacterial and nonbacterial prostatitis by prostatic immunoglobulins

Although inflammatory diseases of most human secretory surfaces are difficult to investigate clinically, the secretory immune system of the human prostate may be studied relatively easily because prostatic fluid may be obtained from the gland by digital massage. We studied inflammatory conditions of the prostate to establish whether we could use the humoral immune response to differentiate these conditions. Using a sensitive solid-phase radioimmunoassay, we measured total IgA and IgG, and IgA and IgG antibodies to Enterobacteriaceae in the serum and prostatic fluid of men with and without prostatic inflammation. These studies show that levels of IgA and IgG in the prostatic fluid of men with bacterial prostatitis are higher than those in men without histories of urinary or prostatic infections. In men with bacterial prostatitis, prostatic antibodies to Enterobacteriaceae were elevated 12 to 18 months after curative treatment and indefinitely after ineffective treatment; anti-Enterobacteriaceal IgG levels returned to normal after infection only with cure. Total IgA and IgG in the prostatic fluid of men with nonbacterial prostatitis--men who have signs of prostatic inflammation without evidence of old or ongoing bacterial infection--are also higher than levels found in uninfected individuals. Although this finding supports an inflammatory etiology for the symptoms seen in nonbacterial prostatitis, no significant IgA or IgG Enterobacteriaceal antibody titers were detected in these patients. This excludes a remote Enterobacteriaceal infection as a cause of nonbacterial prostatitis. These observations confirm that the prostate gland is a distinct part of the male secretory immune system.