17 beta-estradiol induced prostatitis in the rat is an autoimmune disease

Studies suggest that alteration in steroid hormone levels may be one of the factors causing nonbacterial prostatitis (NBP) in rats. We hypothesized that hormonally induced prostatitis in the rat may be an autoimmune disease. Studies were carried out to prove this hypothesis.

We injected 17 beta-estradiol (E2; 250 micrograms/kg. subcutaneously) or vehicle into 1-year-old male rats for 30 days, and isolated and cultured the splenocytes in the presence of con-A (Experiment 1). Approximately 10(7) splenocytes were adoptively transferred into young naive syngeneic rats. To find out whether or not the inflammation is mediated by T-lymphocytes, a pure population of T-lymphocytes from E2-treated 3-month-old rats was injected into young naive syngeneic rats (Experiment 2). To rule out the possibility that the inflammation was due to con-A itself, we cross-linked some T-cells with anti-CD3 antibody before adoptive transfer (Experiment 2).

The recipients of splenocytes from E2-treated animals presented evidence of inflammation in terms of lymphocytic infiltration and presence of degranulated mast cells. Furthermore, we observed in these animals an increase in histamine-releasing peptide (HRP) levels, an indication of plasma extravasation. The T-cells stimulated by anti-CD3 antibody produced a similar degree of inflammation, thereby ruling out the possibility that the inflammation was due to con-A. The results also indicated that the immune response to antigen(s) is not dependent on the age of the animal but is dependent on a population of CD3+ T-cells.

Our results demonstrate that hormonal imbalance and autoimmunity in male rats produce the symptoms of nonbacterial prostatitis.