CD44 mediates Th1 and Th2 lymphocyte rolling and adhesion in TNFα-treated mice. BALB/c mice were left untreated or treated with TNFα for 4 hours prior to the injection of rhodamine 6G–labeled Th1 or Th2 lymphocytes. After basal levels of rolling flux were recorded in TNFα-treated mice, isotype controls (isotype Ab) or a blocking antibody against CD44 were administered. (A) Th1 rolling flux and (B) Th1 rolling velocity in postcapillary venules of the small intestine were determined by intravital microscopy. (C) To determine Th1 cell adhesion, isotype and a CD44-blocking Ab were administered to the mice intravenously prior to Th1 injection. In similar experiments, Th2 rolling flux (D), Th2 rolling velocity (E), and Th2 adhesion (F) were also determined. Data are expressed as the arithmetic means ± SEM of at least 3 animals per group. *P < .05 relative to control group; #P < .05 relative to TNFα treatment group.