Figure 3. Enhanced numbers of CD11b⁺Gr-1⁺ neutrophils in tumors of Ifnb1^–/– mice.

(A) Percentage of CD11b⁺Gr-1⁺ cells (characterized in more detail in Supplemental Figure 1) in tumor is altered in Ifnb1^–/– mice compared with C57BL/6 mice. Flow cytometry of myeloid cells from tumors of Ifnb1^–/– and C57BL/6 mice. Tumors were removed at day 14; single-cell solutions were prepared, stained, and analyzed using the BD LSR II System. Data were analyzed with FACSDiva software. (B and C) Number of myeloid cells in tumors isolated from Ifnb1^–/– mice is higher than in C57BL/6 mice. Tumors were removed, and 10 μm cryosections were prepared and stained for Gr-1 (blue), CD11b (red), and laminin (green). Number of neutrophils was calculated per 20 fields of view. Experiments were repeated at least twice, with at least 5 animals per group. Scale bars: 200 μm, 100 μm, 50 μm, and 20 μm respectively. (D) Percentage and number of CD11b⁺Gr-1⁺ neutrophils in bone marrow and blood are altered in Ifnb1^–/– mice compared with C57BL/6 mice. Experiments were done twice with at least 5 animals per group. Data represent mean ± SEM. *P ≤ 0.01.