Ankylosing spondylitis and HLA-B27: restriction fragment length polymorphism and sequencing of an HLA-B27 allele from a patient with ankylosing spondylitis

Two color analysis of HLA-B27 antigen by flow cytometer--a comparative study by conventional microlymphocytotoxicity, DNA genotyping polymerase chain reaction and flow cytometric measurement

For evaluation of specificity and sensitivity of flowcytometric determination of HLA-B27 antigen, we determined the HLA-B27 on lymphocytes using HLA-B27 monoclonal antibody by flow cytometer. Data were compared to those by conventional Terasaki microlymphocytoxicity test and DNA genotyping Polymerase Chain Reaction (PCR) method. One hundred and ninety four patients with various forms of arthritis were included in this study. Forty one of them were HLA-B27 positive, confirmed by three methods concomitantly with complete accordance. None of serological B27 negative, B7 CREG positive cells were found to be flowcytometric fluorescence positive. Furthermore, there was no significant difference of B27 intensity between different B27 DNA subtypes, nor was there any difference between primary ankylosing spondylitis (AS) and other secondary spondylitis patients as measured by mean channel of fluorescence. It is suggested that flowcytometric measurement of HLA-B27 antigen is a rapid and reliable method for HLA-B27 determination.

HLA and disease

Many human diseases are associated with HLA class I, class II and class III antigens. It appears that the class III antigen disease associations can be explained by a direct defect operating at the level of either the class III gene or its gene product. The mechanism underlying class I and class II antigen disease associations is at present unknown. In this review we have considered thirty diseases which have been ranked according to their relative risk as defined by the frequency of a given HLA antigen in patient and control populations. The chronic inflammatory disorder, ankylosing spondylitis and its association with HLA B27 has been used as a model to study the HLA linked diseases. We have suggested that the disease may be caused by the Gram-negative microorganism Klebsiella which has antigenic similarity to HLA B27. It is proposed that some antibodies made against Klebsiella bind to HLA B27, thereby acting as autoantibodies leading to the pathological sequelae of chronic inflammatory arthritis. This is the crosstolerance hypothesis or molecular mimicry model and it has been compared to the receptor model. It is further suggested that the crosstolerance hypothesis can be utilised as a general theory to explain the association of other diseases with the class I and class II antigens, and offer a possible explanation for the polymorphism of HLA.