The Tec family kinase Btk is required for E-selectin–mediated slow rolling and Gα_i-independent adhesion, but not for chemokine-induced arrest in vivo. (A) The carotid artery of chimeric mice reconstituted with bone marrow from WT mice (n = 3) or Btk^−/− mice (n = 3) was cannulated with a catheter, which was connected to autoperfused flow chambers. Average rolling velocity of neutrophils on E-selectin (left) and E-selectin and ICAM-1 (right) is presented as means ± SEM. The wall shear stress in all flow chamber experiments was 5 to 6 dyn/cm². (B) Isolated bone marrow neutrophils were resuspended in plasma, and the rolling velocity on either E-selectin alone or E-selectin plus ICAM-1 was measured. In these experiments, a shear stress of 3 dyn/cm² was used (n = 3). (C) Mixed chimeric mice were generated by injecting bone marrow cells from LysM-GFP⁺ WT mice and Btk^−/− mice into lethally irradiated WT mice. Cumulative histogram of rolling velocities of 100 GFP⁺ (WT; ●) and 100 GFP⁻ (Btk^−/−; ○) leukocytes in inflamed cremaster muscle venules of mixed chimeric mice (n = 4) treated with PTx and a monoclonal blocking P-selectin antibody (RB40.34). Inset data are means ± SEM. (D) Numbers of adherent cells per square millimeter in murine cremaster muscle venules. The cremaster muscle was exteriorized 2 hours after intrascrotal injection of 500 ng TNF-α in chimeric mice reconstituted with bone marrow from WT mice or Btk^−/− mice. The dotted line indicates the number of adherent cells in WT mice treated with PTx and monoclonal blocking E-selectin antibody (9A9). #P < .05; *P < .05 vs other groups.