MOUSE POLYMORPHONUCLEAR GRANULOCYTE BINDING TO EXTRACELLULAR-MATRIX MOLECULES INVOLVES BETA-INTEGRINS

The mechanism of adhesion of purified mouse polymorphonuclear granuloc ytes (PMN) to extracellular matrix proteins characteristic of basement membranes and the interstitium has been investigated and compared wit h the adhesion of a mouse progranulocytic cell line, 32DC13, and a mou se monocytic cell line, WEHI 78/24. All three cell types bound specifi cally to fibronectin and vitronectin to different degrees under differ ent cellular activation states. 32DC13 bound to fibronectin and vitron ectin strongly, and this binding increased upon cellular activation wi th phorbol 12-myristate-13-acetate (PMA) but not with formyl-Met-Leu-P he. Only 32DC13 showed significant binding to laminin-1. By contrast, WEHI 78/24 and PMN bound only fibronectin and vitronectin; this bindin g was weak and was altered only marginally upon activation with PMA. I n the case of WEHI 78/24, a slight increase in adhesion both to fibron ectin and to vitronectin was observed after cellular activation with P MA, while PMN adhesion to both substrates was slightly reduced. The me chanism of binding to fibronectin and vitronectin was similar in the t hree cell types. The integrin alpha 5 beta 1 mediated fibronectin adhe sion, demonstrating for the first time the existence of a functionally active beta 1 integrin on mouse PMN. Vitronectin binding was mediated by alpha v beta 3, as demonstrated by the ability of alpha v-specific cyclic L-Arg-L-Gly-L-Asp-D-Phe-L-Val (RGDfV) peptide (EMD66203), and anti-beta 3 antibody to inhibit cell adhesion. 32DC13 adhesion to lami nin-1 was via the alpha 6 beta 1 integrin. None of the three cell type s tested bound to the basement membrane proteins collagen type IV and perlecan, or to the interstitial stromal constituents tenascin, collag en types I, V and VI. Interestingly, perlecan and collagen type IV wer e found to repel all three cell types. The relative inability of PMN, WEHI 78/24, and 32DC13 to bind to extracellular matrix proteins charac teristic of basement membranes and their ability to bind inflammatory markers of the interstitium is discussed with respect to leukocyte ext ravasation processes.