They also found that IgM reactivities to myeloperoxidase (MPO), CD99, collagen III, insulin-like growth factor binding protein 1 (IGFBP1), and cardiolipin were decreased in SLE, suggesting that the IgM autoantibodies might enhance resistance to SLE, consistent with the findings by Li and colleagues [22]. Here, CD99 is linked to systemic lupus erythematosus.