Number of bone marrow cells in wild-type and GM-CSF−/− mice following Listeria infection. GM-CSF−/− mice (▪) and wild-type mice (□) were either uninfected or infected intraperitoneally with 2 × 10⁵Listeria for 1 or 3 days. Bone marrow cells were flushed from the tibia of individual mice. Data represent the mean and SD of individual tibia of five mice in each group. *P < .05 and **P < .01 compared with wild-type mice which were infected with the same dose ofListeria. Results were from one of three similar experiments. (a) Total cells recovered per tibia. (b) Colony forming cells per tibia. (c) Gr1⁺ cells per tibia. (d) F4/80⁺cells per tibia.