[Application of the gel test using and anti-IgA antiglobulin for the immunologic diagnosis of autoimmune hemolytic anemia with a negative direct Coombs test].

Autoimmune hemolytic anemias (AIHA) are characterized by hyperhemolysis associated with the presence of the immunoglobulins IgG, IgM or IgA on the red cell membrane. These immunoglobulins react as auto-antibodies against the red cell auto-antigens of the patient. The diagnosis is supported by clinical and biological signs of hemolysis, and by the identification of the auto-antibodies using the direct antiglobulin test (DAT). Here we report 14 cases of patients who showed the clinical and biological profile of AIHA, but who gave a negative DAT. We therefore tried to determine the presence of IgA on the red cell membrane with a method more sensitive than the DAT: the gel test using anti-IgA. With such a gel test, we demonstrated that there were IgA auto-antibodies on the red cell membrane in the 14 cases, therefore confirming the diagnosis of AIHA. We discuss the interest of performing a gel test with anti-IgA in each case where AIHA is suspected, but in which a negative DAT has been observed.