Influence of HLA B27 on Reactive Arthritis
How is Reactive Arthritis acquired? What is the influence of HLA B27?
Susceptibility to ReA may be conferred by the specific class I major histocompatibility antigen, HLA-B27. However, the development of ReA is strictly dependent on infection with certain organisms predominantly acquired through mucosal surfaces, enterogenic or urogenital (see Question 6). In hospital-based reports, HLA-B27 is present in 60% to 80% patients with ReA. These patients tend to have more severe arthritis, extraarticular manifestations, higher prevalence of sacroiliitis, and a protracted course. Notably in population-based studies, patients with ReA are less likely to be HLA-B27-positive (30% or less in some ethnic groups). These cases have a milder oligoarthritis with fewer systemic symptoms or extraarticular manifestations.