It has been reported that G-CSF is a factor which acts on myeloid stem cells and enhances their differentiation into neutrophilic leukocytes (Metcalf et al., Blood, 67 (1), 37-45 (1986)), and that it also stimulates functions of differentiated neutrophilic leukocytes such as phagocytosis, O2 - -production and the like (Yuo et al., Blood, 70 (2), 404-411 (1987)).