(A) Bone marrow differential cell counts. Differential cell counts (total of 400 cells each) were performed on bone marrow smears. Data are shown as arithmetic means ± SD. Pro, promyelocytes; Immature Neut, neutrophilic myelocytes and metamyelocytes; Mature Neut, neutrophilic band, mature ring, and polymorphonuclear forms; Eryth, nucleated erythroid cells; Lymph, lymphocytes; Eosin, eosinophilic cells. Control, n = 6; Tg259, n = 6; Tg237, n = 6. (Inset) Ratios of mature to immature neutrophilic cells. ∗ indicates a significant shift toward immature cells is present in the bone marrow of the transgenic mice, P = 0.004. (B) Density of bone marrow neutrophilic cells. Bone marrow cells were separated into low and high density fractions on a Percoll step gradient. Total numbers of cells present in each fraction were determined. Differential cell counts (total of 100 cells each) were performed on cytospins of each fraction, with cells morphologically identified as neutrophilic (neutrophilic myelocytes, metamyelocytes, ring, band, and polymorphonuclear forms) or nonneutrophilic. Total cell counts and differential counts were used to calculate the mean percentages of neutrophilic cells present in the high density fractions. Data are shown as arithmetic means ± SD. Control, n = 7; Tg259, n = 5; Tg237, n = 6. †, Control vs. Tg259, P = 0.0006. ‡, Control vs. Tg237, P = 0.00002; Tg259 vs. Tg237, P = 0.002.