CD44 mediates TNFα-induced leukocyte rolling flux. BALB/c mice were left untreated or were treated with TNFα for 4 hours prior to intravital microscopy and antibody administration. (A) Endogenous leukocyte rolling flux in control and TNFα-treated mice was determined using intravital microscopy. After basal levels of rolling flux were recorded in TNFα-treated mice, isotype controls (isotype Ab) or a blocking antibody against CD44 were administered. (B) Endogenous leukocyte rolling velocity. (C) The number of rolling endogenous leukocytes per 100 μm and (D) endogenous leukocyte adhesion was quantified. Data are expressed as the arithmetic means ± SEM of at least 3 animals per group. *P < .05 relative to untreated controls; #P < .05 relative to TNFα-treated animals.