Pep-1 (HABP52 in this paper) isolated by phage display has been shown to bind to hyaluronic acid (HA) with high affinity and to inhibit leukocyte adhesion to HA. This peptide lacks similarity to the HA binding motifs discussed above, in that 2 of 16 amino acids are basic. In contrast, HABP35 possesses 11 of 27 basic residues, which may help contribute to ionic binding of this peptide to negatively charged HA. Pep-1/HABP52 inhibits contact hypersensitivity responses in mice by blocking skin-directed trafficking of inflammatory leukocytes.