Eotaxin stimulates release of colony-forming units from femoral bone marrow. (A) Total eosinophil and total other leukocyte release from the perfused hind limb stimulated by a 10-minute infusion of eotaxin (3 nmol/L) or vehicle (PBS/0.1% BSA), counted in an improved Neubauer hemacytometer. Results show the total number of eosinophils and other leukocytes released during the 60-minute perfusion period, mean ± SEM (n = seven to eight perfusions). (B) GM-CFU (▪) and Eo-CFU (□) release after a 10-minute infusion of eotaxin (3 nmol/L) or vehicle. The colony-forming assay was performed in Methocult GF H4534 methylcellulose-based medium supplemented with IL-5 (3 nmol/L). Results are expressed as the number of GM-CFU or Eo-CFU present per 5 × 10⁵ total leukocytes released during the 60-minute perfusion period, mean ± SEM of seven to eight perfusions, CFU assay performed in duplicate. A significant difference between Eo-CFU released in eotaxin and in vehicle infused groups is indicated by ***(P < .001). (C) Colony-forming unit assay of leukocytes released by eotaxin (3 nmol/L) performed in Methocult GF H4534 medium supplemented with either PBS (A), IL-5 (3 nmol/L) (B), or eotaxin (3 nmol/L) (C). Results are expressed as the number of GM-CFU (▪) or Eo-CFU (□) present per 5 × 10⁵ total leukocytes released during the 60-minute perfusion period, mean ± SEM of three perfusions, CFU assay performed in duplicate. A significant difference between the number of Eo-CFU formed in the presence of IL-5 compared with either PBS or eotaxin is indicated by *(P < .05).