Chemotactic responses of Pirb^−/−-granulocytes to chemokine stimulation. Chemotaxis was assessed in eosinophils (A-C) isolated from CD2–IL-5Tg/Pirb^−/− (WT), CD2–IL-5Tg/Pirb^+/+ (Pirb^+/+), or thioglycolate-elicited neutrophils (D) obtained from wild-type (WT) or Pirb^−/− mice using a transwell-chamber system in response to recombinant mouse eotaxin-1 (1-100 ng/mL; A), eotaxin-2 (1-100 ng/mL; B), LTB₄ (0.1-250 nM; C,D) for 180 minutes. Data are expressed as means plus or minus SD fold increase over baseline chemotaxis of n = 4; *P < .05; **P < .01; ***P < .001 when comparing WT and Pirb^−/− cells.