Purpose: Granulomatous prostatitis is characterized by a pattern of granulomatous inflammation in the prostate. In most cases the etiology is unknown. Based on the hypothesis that granulomatous prostatitis may be an autoimmune disease we performed intermediate and selective high resolution typing of HLA-DR in a group of patients with the disease and compared the frequency of class II HLA phenotypes to that in a control group of volunteer marrow donors in the military.
Materials and methods: Histological records from 1 institution from 1990 to 2000 revealed 12 patients with diffuse granulomatous prostatitis. Three patients were dead and 1 refused blood drawing. Peripheral blood from the remaining 8 patients was typed along with blood from an additional 3 identified at the practice of one of us from 1999 through 2002. All slides were reviewed by 1 pathologist. Intermediate resolution typing of HLA-A, B and DR was performed by polymerase chain reaction-sequence specific oligonucleotide probe. High resolution, allele specific identification of HLA DR15 was performed if patients were DR15 positive by intermediate resolution typing.
Results: There were 3 black and 8 white individuals identified with diffuse nonspecific granulomatous prostatitis. Six of 8 white patients (75%) were HLA-DR15 by intermediate resolution typing. One of the 3 black American patients (33%) was HLA-DR15. In the control group 127 of 451 white (28.2%) and 23 of 89 black (25.8%) volunteer marrow donors were HLA-DR15. The case-control comparison of white patients was significantly different (Fisher's exact test p = 0.0086). There were no statistically significant differences between case-control comparisons for any other HLA-DR phenotype. High resolution DR15 typing showed that the white patients were HLA-DRB1*1501 and the black patient was HLA-DRB1*1503.
Conclusions: The data suggest an association between HLA-DRB1*1501 and granulomatous prostatitis. HLA-DR15 is strongly associated with other autoimmune diseases, notably multiple sclerosis. The data are consistent with an autoimmune etiology for nonspecific granulomatous prostatitis.