Hematopoietic progenitor assays. (A) Bone marrow mononuclear cells were plated in methylcellulose-containing media supplemented with the indicated cytokine. Hematopoietic colonies containing greater than 30 cells were scored after 7 to 8 days (these colonies include CFU-GM, CFU-M, and CFU-G). Six sex- and age-matched mice of each genotype were analyzed. Data represent the mean ± SD. No significant differences in progenitor frequency were detected among the different genotypes. (B) Neutrophil production in hematopoietic colonies. The percentage of neutrophils was determined by manual 300-count leukocyte differentials on Wright-stained cytospins of cells recovered from entire methylcellulose cultures. Cultures were stimulated with the indicated cytokine for 8 days. Data represent the mean ± SD.