Patients with gram-negative septicemia complicating leukemia were shown to be unable to trigger the generalized Shwartzman reaction (gSr) despite the presence of shock and hypercoagulable levels of fibrinogen, factor V, and factor VIII. It is postulated that granulocytes are necessary for disseminated intravascular coagulation (DIC) to occur as the result of endotoxemia. The severe leukopenia in these patients acted in a similar manner to nitrogen mustard preparation of rabbits to protect them against the gSr.