HLA phenotypes and joint affection in psoriasis, acute anterior uveitis and chronic prostatitis.

In a prospective study, 50 patients hospitalized for psoriasis, 34 patients hospitalized for acute anterior uveitis (AAU) and 29 patients hospitalized for chronic prostatitis, were examined. The expected increased frequencies of HLA B13 and HLA B17 in psoriasis and of HLA B27 in AAU over healthy people were found. No unsuspected association between HLA antigens was observed. Psoriatic patients with peripheral joint affection frequently had affected sacro-iliac joints and were HLA B27 negative. Joint affection was frequently seen in HLA B27 positive patients with psoriasis or AAU. In the patients with AAU, 12 out of 22 patients positive for HLA B27 exhibited radiographical sacro-iliitis. This high prevalence of sacro-iliitis suggests an interaction between genes predisposing for AAU and sacro-iliitis. Asymptomatic sacro-iliitis was found in both HLA B27 positive and negative patients. The low frequency of clinical symptoms in psoriatic sacro-iliitis could not be explained by the absence of HLA B27.