Enhanced interferon-gamma production by lymphocytes induced by a mitogen from mycoplasma arthritidis in patients with ankylosing spondylitis.

We have examined proliferation of and interferon-gamma (IFN-gamma) production by peripheral blood lymphocytes induced by a purified mitogen derived from mycoplasma arthritidis (MAS) in patients with seronegative spondylo-arthropathies and healthy individuals. In all patients and healthy controls MAS exerted a potent nonspecific lymphoproliferation. In contrast, only patients with ankylosing spondylitis (ASp) showed a strong IFN-gamma production after stimulation with MAS. The maximal IFN-gamma response was observed in HLA-B27+/HLA-DQw3+ patients. However, healthy controls with the HLA-DQw3 haplotype with or without the presence of HLA-B27 exhibited also a slight but statistically not significant increase of IFN-gamma production. Moreover, in this study we have found an enhanced frequency of HLA-DQw3 in patients with ASp and reactive arthritis. This immunogenetic association explains the enhanced lymphocyte reactivity in these inflammatory rheumatic disorders to mycoplasmal antigens.