Agranulocytosis following infectious mononucleosis.

A girl developed acute agranulocytosis (45/mm3), 37 days after the onset of infectious mononucleosis. The bone marrow showed myeloid hyperplasia with maturation arrest and erythroid hypoplasia. A normal amount of colony forming units of granulocytes and macrophages (CFU-GM) colonies with a relative high number of clusters was observed. Neither anti-neutrophil antibodies nor circulating inhibitors of colony growth were found in serum. Granulocyte and macrophage colony stimulating factor (GM-CSF) activity in the patient's serum rose at this time. The agranulocytosis lasted 5 days and her clinical state soon improved. These results suggested that agranulocytosis was presumably not due to serum factors, including auto-antibodies and/or suppressive substances, and that Epstein-Barr virus (EBV) had some direct or indirect effect on the marrow cells of the myeloid series.