Adhesion of rat neutrophils (PMN) and mononuclear cells (MNC, lymphocytes and monocytes) to untransfected and rat (panel a, n = 7) or human (panel b, n = 6) VCAM-1–transfected CHO cells. Adhesion was tested to nontransfected CHO cells, or CHO cells transfected with VCAM-1 in the presence or absence of α4 MoAb TA-2. Adhesion of rat neutrophils to rat VCAM-1 was also tested in the presence of the β1 antibody Ha2/5. β1 blocking studies were not performed for neutrophil adhesion to human VCAM-1. Data are presented as mean percent adherence ± SEM. *(P < .05) and **(P < .01) indicate values significantly different from percent adhesion to VCAM-1–transfected CHO-cells. (□), CHO; (▪), VCAM-1 CHO; (▨), VCAM-1 CHO + anti-α4 MoAb; (▩), VCAM-1 CHO + anti-β1 MoAb.