The erythrocyte-granulocyte rosette. An immune cellular interaction found in some cases of autoimmune hemolytic anemias.

Erythrocyte-granulocyte rosettes (EGR) were found in the capillary blood of two cases of autoimmune haemolytic anemia, the first caused by an IgM non-I antibody and the second by an IgG. Both antibodies activated complement, and C3b was demonstrated on the erythrocytes. The rosettes appeared as arrangements of 6-10 red cells adhering to a central granulocyte; phagocytosis was most generally absent. The finding of EGR in the capillary blood may be useful for the recognition of complement activation up to the C3b stage in some cases of autoimmune haemolytic anemia.