Figure 4. Age reduces expression of receptors and ligand required for proper neutrophil clearance. Neutrophils isolated from the blood of naïve young and aged mice were stained for neutrophil identification markers (CD45+/CD11b+/Ly6CInt/Ly6GHi), surface chemokine receptors CXCR2 (A), CXCR4 (B) and the adhesion molecules L-selectin (C) and CD44 (D). Serum was taken from young (3 month) or aged (22 month) old animals 24 hours following sham or stroke surgery. n=7-12 animals/group. CXCL12 and CXCL2 were measured via multiplex (E). Two-way ANOVA was performed, followed by individual T-Tests with Sidak’s correction. (F) A schematic figure of the differential roles of CXCL12 and CXCL2 in circulating neutrophil homeostasis. *p≤0.05, **p=<0.01, ***p=<0.001.