Cutting edge: Persistent fetal microchimerism in T lymphocytes is associated with HLA-DQA1*0501: Implications in autoimmunity

The host's MHC genotype plays a critical role in susceptibility to autoimmu ne diseases. We previously proposed that persistent fetal microchimerism fr om pregnancy contributes to the pathogenesis of autoimmune diseases such as scleroderma. In the current study, we investigated whether the specific ho st MHC genotype is associated with persistent microchimerism among T lympho cytes in women with scleroderma and in healthy women. Fetal microchimerism among T lymphocytes was strongly associated with HLA DQA1*0501 of the mothe r (odds ratio (OR) = 13.5, p = 0.007, p corrected (pc) = 0.06) and even mor e strongly with DQA1*0501 of the son (OR = infinity; p = 0.00002, pc = 0.00 02). This is the first description of an association between persistent fet al microchimerism in maternal T lymphocytes and specific HLA class II allel es. Although the association was observed in both healthy women and in wome n with scleroderma, the finding suggests an additional route by which HLA g enes might contribute to susceptibility to autoimmune disease.