Enhanced monocyte accumulation within the peritoneum of Mac-1^-/- mice. WT (□, n = 4) and Mac-1^-/- mice (•, n = 4) were injected intraperitoneally with sterile TG to elicit monocyte infiltration into the peritoneum. At different times after TG injection, peritoneal lavages were performed. The total number of leukocytes in the lavage was determined with a Coulter counter, and the percentage of monocytes/macrophages was determined by FACS analysis using mAb F4/80 and by Hema3 staining of Cytospin smears. Monocyte accumulation in the peritoneal cavity was enhanced in Mac-1^-/- mice (•) compared to the control WT mice (□), whereas the reduction in peritoneal macrophages, possibly due to their spontaneous efflux out of the peritoneum, between day 4 and 8 was similar. The data represent the mean ± SD of 3 mice. WT versus Mac-1^-/-: ^**P < .005; ^*P < .02.