CD22 and autoimmune disease: CD22 is one of the most common antigens and is highly expressed in hematological malignancies, including human B-cell lymphomas and leukemias.147–149 Exon 12 depletion in infant B-precursor leukemia cells promotes their growth and survival.150 Moreover, CD22 conduces to protecting against pathogenic infection, and CD22 deficient mice are extremely sensitive to infection.151 In addition, CD22 expression is closely related to autoimmune disease, and CD22 levels are decreased in patients with systemic lupus erythematosus (SLE) and increased after effective treatment.152,153