[Flow cytometry analysis of IGG subclasses of auto- and alloantibodies in autoimmune hemolytic anemia and hemolytic disease of the newborn].

Red cell IgG antibodies capable of causing hemolytic disease of the newborn (HDN) or autoimmune hemolytic anemia (AIHA) have been analyzed concerning their IgG subclasses using flow cytometry. The results were always in agreement with those of the direct Coombs test. Anti-A and/or anti-B able to cause HDN belonged to the IgG1 subclass (4/8 cases) or to the subclasses IgG1 and IgG2 (4/8 cases). In 3 out of 4 cases of HDN caused by Rh antibodies the antibodies belonged to the subclasses IgG1 and IgG3. In patients with lymphoma but without AIHA, red cell autoantibodies were often found to be IgG1 only (n = 10), in low concentrations. In cases of acute AIHA in adults caused by IgG autoantibodies the subclass IgG3 was found in addition to IgG1 in 4/5 cases. In our opinion flow cytometry should become substantial for immunohematological diagnostics.