CD8A and arthritic joint disease: This model does not address the immunological function of MHC-II that is detected on T cells in the blood at the peak of the primary effector response [55] or on bulk CD8 T cells in the blood of patients during chronic immune activation such as is associated with HIV infection [56], arthritis and lupus [57]; and therefore, the function of MHC-II on CD8 T cells during the latter stages of an immune response remains a mystery.