Compensatory CD11b upregulation in α₃β₁-depleted mice negatively regulates TLR2 responses. (A) Surface expression of CD11b levels on BM neutrophils (gated as Ly6G^highCD115^low cells) from α₃ cKO and control Ela-Cre mice. Total BM cells (10⁶) were stimulated with Pam₃CSK₄ (1 μg/mL) over time, as indicated (n = 4/time point). Data are expressed as mean MFI ± SD (top) or mean fold change compared with unstimulated neutrophils ± SD (bottom). *P < .05 (2-way repeated measures ANOVA with Bonferroni posttest). (B) Left: Representative western blot images of Syk phosphorylation kinetics in neutrophils from α₃ cKO and Ela-Cre mice after Pam₃CSK₄ (1 μg/mL) stimulation over indicated periods. Total cell lysates were analyzed by western blotting to determine the extent of Syk phosphorylation at Tyr³⁴⁶ (equivalent to Tyr³⁵² for humans). Right: Densitometric analysis of Syk phosphorylation. phospho-Syk was normalized to total Syk at each time point and expressed as mean fold increase compared with time = 0 minutes. Data are expressed as mean ± SEM from 3 independent experiments. *P < .05 (2-way repeated measures ANOVA with Bonferroni posttest). (C) Left: Representative western blot images of total MyD88 in neutrophils from α₃ cKO and Ela-Cre mice after Pam₃CSK₄ (1 μg/mL) stimulation over time. Right: Densitometric analysis of bands expressed as % of control group (time = 0 minutes). MyD88 levels were normalized to actin at each time point. Data are expressed as mean % change ± SEM from 4 independent experiments.