Longitudinal studies of prostatic fluid immunoglobulin in men with bacterial prostatitis

To better characterize the apparent secretory immune response of the prostate to bacterial infection of the genitourinary tract, we assayed serial expressed prostatic secretion (EPS) specimens for total and antibacterial immunoglobulin. Three men with bacterial prostatitis, including 2 otherwise healthy men with chronic infections and 1 man with IgG multiple myeloma and an acute infection, were studied. In the former 2 cases the infections were associated with greater increases in total EPS IgA than total EPS IgG or IgM. The patient with multiple myeloma had markedly elevated serum IgG levels and subnormal serum IgA and IgM levels and the acute infection was accompanied by increases in total EPS IgG and IgM but consistently low total EPS IgA. Antibacterial EPS IgA, which was measurable in each case, was always quantitatively greater than antibacterial EPS IgG. Antibacterial IgM was never detectable. Alterations in the concentrations of antibacterial EPS IgG and IgA were generally not associated with comparable alterations of total EPS IgG and IgA, respectively, and the concentrations of antibacterial EPS IgG and IgA did not correlate well with the clinical or bacteriologic response to antimicrobial therapy. The concentration of antibacterial IgA expressed as a function of total IgA was as much as 1550 times greater in the EPS than in the serum. However, the relative concentrations of antibacterial IgG and IgM were similar in the EPS and serum. These data suggest local synthesis of antibacterial IgA in the prostate that persists following eradication of the infection and that is regulated independent of both the systemic immune response and the concentration of total prostatic fluid immunoglobulin.