Distinct resident leukocyte population in the female peritoneal cavity. (A) Increased total resident cell number in peritoneal (n = 13 mice; 3 independent groups) and pleural (n = 5 mice) cavities of female compared with male mice. (B) Total cell number and (C) percentage of F4/80⁺ macrophages, CD3⁺ T lymphocytes, CD19⁺ B lymphocytes, and GR1⁺ granulocytes in peritoneal cavity of male and female mice were determined by flow cytometry (n = 7 mice). (D) Increased total resident CD8⁺ and CD4⁺ T lymphocytes but not CD4⁺/CD25⁺ T-regulatory or δγ T lymphocytes in female peritoneal cavity (n = 4 mice). All values are expressed as means ± SEM. All comparisons are relative to male. *P < .05; **P < .01; and ***P < .001 by Student t test.