Departments of 1Pathology (Immunology Section) and 2Internal Medicine Salmaniya Medical Complex, Ministry of Health, Bahrain.
The human leucocyte antigens (HLA) are known to be associated with some diseases, the most common is HLA-B27 and ankylosing spondylitis (AS). We studied hundred patients suffering from low back pain and radiologic sacroiliitis and 260 normal healthy individuals. Two methods were used for HLA-B27 typing namely complement mediated lymphocytotoxicity and flow cytometery. Results obtained by the two methods were in agreement. The percentage of B27 individuals among the total number of patients with back pain was 25% while in the control group it was 2.7% (P< 0.001). Among patients suffering from AS, the percentage of B27 was 96% and relative risk was 85%. Flow cytometery had the advantages of being rapid, simple and accurate. The monoclonal antibody used had the ability to identify all subtypes of B27 known to be associated with AS. It is concluded that HLA B27 is a rare allele among healthy individuals in Bahrain and that flow cytometery is an excellent method for HLA-B27 typing to identify patients at high risk for AS.