HLA-B27 and HLA-B51 determination in Tunisian healthy subjects and patients with suspected ankylosing spondylitis and Behçet's disease.

The aim of this retrospective study is to assess the frequency of HLA-B27 and HLA-B51 in healthy subjects from the center of Tunisia and to investigate their usefulness in the diagnosis of ankylosing spondylitis (AS) and Behçet's disease (BD), respectively. Microlymphocytotoxicity test was used to perform serologic HLA typing in a group of 124 healthy volunteers and a group of 365 patients suffering from clinical manifestations of AS and/or BD. HLA-B27 was found in 3.2% of healthy subjects and in 42.9% of patients with AS (P < 0.00006). HLA-B51 is, however, found in 16.1% of healthy subjects and in 30.0% of patients with BD (P > 0.05). Unlike HLA-B51, which seems to be as frequent in Tunisian patients with BD as in healthy subjects, HLA-B27 is more frequent in patients with AS than in controls. This highlights the usefulness of HLA-B27, rather than that of HLA-B51, in the diagnosis of the respective diseases.