CD40LG and autoimmune hemolytic anemia: The forms of CA (16–32% of the cases), the IgM class, are directed against the self-antigens of System I and activated at a thermal optimum of 4°C.[1] Under pathological conditions, CAs directing against the RBCs may cause the consequent hemolysis, which is defined as autoimmune hemolytic anemia.[7] RBC agglutination can cause a normal Hgb concentration with decreased RBC counts and Hct, and a marked elevation of MCH and MCHC levels, thus leading to clinically unreliable results.