[Antibiotics-induced agranulocytosis. Patient's IgG inhibits a GM colony formation]

The pathogenesis of Cefmetazole (CMZ) induced agranulocytosis was investigated in the case of a 40-year-old man who developed agranulocytosis while he was under treatment with CMZ. Although concentration of CMZ in serum is not detected, patient's serum drawn at the time of diagnosis suppressed normal allogeneic marrow GM colonies in vitro. Normal IgG purified from serum had no effect on GM colony formation in vitro. However, patient's IgG purified from serum drawn at the time of diagnosis suppressed normal allogeneic marrow GM colony in vitro without CMZ. These studies suggest that CMZ-induced agranulocytosis is immunologically mediated through an IgG inhibitor which seems to exert its effect on GM colony formation.