FACS analysis of adhesion relevant molecules on Gr-1⁺ blood cells isolated from E13 to E18 fetuses, newborn, and adult mice. Expression of the surface molecules (A) Mac-1, (B) LFA-1, (C) PSGL-1, and (D) CXCR2 including appropriate isotype controls are shown as mean fluorescence intensity values (mean ± standard error of the mean) from ≥3 experiments per group. (E) In addition, FITC-labeled fMLP binding to Gr-1⁺ fetal and adult cells was investigated in the absence or presence of excess (500-fold) unlabeled fMLP. Finally, (F) P-selectin and (G) E-selectin IgG chimeric protein binding (±EDTA) to Gr-1⁺ blood cells is shown (mean fluorescence intensity values, mean ± standard error of the mean from n ≥ 3 mice per group). Significant differences (P < .05) vs adult values are indicated by the asterisk.