Expression of fusion regulatory proteins (FRPs) on human peripheral blood monocytes. Induction of homotypic cell aggregation and formation of multinucleated giant cells by anti-FRP-1 monoclonal antibodies
Tabata, N.; Ito, M.; Shimokata, K.; Suga, S.; Ohgimoto, S.; Tsurudome, M.; Kawano, M.; Matsumura, H.; Komada, H.; Nishio, M.
Journal of Immunology 153(7): 3256-3266
1994
ISSN/ISBN: 0022-1767 PMID: 8089497 Document Number: 422570
Fusion regulatory proteins (FRPs) are newly defined cell surface molecules that enhance and/or induce virus-mediated cell fusion. Anti-FRP-1 Abs reacted with all of the established cells derived from humans and monkeys, whereas FRPs were found to be selectively expressed on a fraction of monocytes in human PBMCs. Granulocytes expressed no FRP-1 molecules, but approximately 18% of granulocytes expressed FRP-2 molecules. Alveolar macrophages also expressed FRP-1 molecules. FRP-1 expression was enhanced by culture of monocytes, but CD14 expression was not influenced by cultivation. Anti-FRP-1 Abs induced homotypic cell aggregation and multinucleated giant cell formation of monocytes. Anti-beta-2 integrin Ab blocked anti-FRP-1 Ab-induced cell aggregation, and anti-beta-1 integrin Ab and fibronectin inhibited anti-FRP-1 Ab-induced polykaryocyte formation. There was no competitive binding to monocytes between anti-FRP-1 Ab and anti-beta-1 or anti-beta-2 integrin Ab or fibronectin. Furthermore, there was no enhancement of beta-1 and beta-2 integrin expression by anti-FRP-1 Ab on monocytes. These findings suggest that anti-FRP-1 Ab activated integrin systems, and that the functions of antiFRP-1 Ab were demonstrated through the activated integrin systems. Furthermore, it is inferred that integrin systems are involved in polykaryocyte formation of monocytes.