CXCL1 in mast cells lacking TLR4 activity. (A) Consecutive peritoneal wall tissue sections of TLR4^mut mice immunostained for toluidine blue (mast cells) and chemokine CXCL1 following 1 hour of PBS or LPS stimulation. Arrows indicate mast cells overlapping with CXCL1-expressing cells. Tissue sections are representative of 2 experiments with n = 4 mice per group. (B-D) Numbers of mast cells releasing CXCR1-expressing granules of mice treated with LPS or PBS for 1 hour as a percentage of total mast cells in peritoneal wall sections of (B) TLR4^−/−, (C) MyD88^−/−, or (D) TRIF^−/− mice compared with control C57BL/6 mice. Data are shown as mean ± SEM (n = 4-7 mice/group). *P < .05; **P < .01; and ***P < .001.