CD44 and graft versus host disease: Antibody blockade of CD44, CD44 deficiency, or enzymatic depletion of endothelial HA (by administration of hyaluronidase) have been shown to decrease neutrophil, monocyte, and/or lymphocyte recruitment and attenuate disease activity in models of arthritis (20, 21), dermatitis (22), peritonitis (10), myositis (13), experimental autoimmune encephalomyelitis (23), orchitis (24), retinitis (25), allergic asthma (26), and graft-versus-host disease (27).