Heterogenous glycosylation of ICAM‐3 and lack of interaction with Mac‐1 and p150,95

Intercellular adhesion molecule (ICAM)‐1, ICAM‐2, and ICAM‐3 have been identified as counter‐receptors for the leukocyte integrin lymphocyte function‐associated antigen 1 (LFA‐1). The other leukocyte integrins, Mac‐1 and p150,95, also interact with ICAM‐1. ICAM‐1 and ICAM‐3 are highly homologous, and an undefined ligand for Mac‐1 is presnt on neutrophils where ICAM‐3 is well expressed. In addition, glycosylation has been shown to affect the interaction of ICAM‐1 with Mac‐1. We therefore sought to characterize ICAM‐3 heterogeneity and determine whether ICAM‐3 was a ligand for either Mac‐1 or p150,95. Despite extensive differences in N‐linked glycosylation, ICAM‐3 purified from lymphoid cells and from neutrophils supports adhesion of LFA‐1‐bearing cells equally well; however, neither supports adhesion of Mac‐1 or p150,95‐expressing chinese hamster ovary cell transfectants. Similarly, purified Mac‐1 does not support adhesion of ICAM‐2 or ICAM‐3‐expressing L cell transfectants. ICAM‐3 on neutrophils does not participate in Mac‐1‐dependent homotypic aggregation. Thus, ICAM‐3 is not a counter‐receptor for either Mac‐1 or p150,95.