Granulocyte transfusions have been advocated by some for the treatment of severe, progressive infections in neutropenic patients who fail to respond to antimicrobial agents and recombinant hematopoietic growth factors. We conducted the current study to determine an appropriate method of granulocyte mobilization in healthy donors, and to evaluate the safety and efficacy of granulocyte transfusion therapy in patients with neutropenia-related infections. To mobilize granulocytes (n=55), healthy normal donors were stimulated in one of the following ways: (1) dexamethasone, 3 mg/m2 intravenously 15 min prior to leukapheresis (n = 5); (2) granulocyte colony-stimulating factor (G-CSF), 5 microg/kg subcutaneously 12 to 14 h prior to collection (n=37); or (3) G-CSF and dexamethasone (n= 13). The mean granulocyte yield from stimulation with G-CSF plus dexamethasone was significantly higher than from stimulation with dexamethasone or G-CSF alone. Twenty-five patients with severe neutropenia-related infections unresponsive to appropriate antimicrobial agents received a total of 55 granulocyte transfusions. The patients from whom fungi or Gram-negative organisms were isolated showed a more favorable response than those infected with Gram-positive organisms. However, the responses to the granulocyte transfusion therapy could not be correlated with the transfused dose, mobilization agents, or the 1 h or 24 h post-transfusion absolute neutrophil counts. We conclude that granulocyte transfusion therapy may be clinically useful for neutropenia-related infections by fungi or Gram-negative organisms.