Identification of novel adhesion proteins in mouse peritoneal macrophages.

When mouse peritoneal macrophages were made to adhere firmly on glass surface and then removed by sequential treatment with hypotonic triethanolamine and Nonidet P-40, a set of proteins were found to be left behind at the sites of adherent cells. Such glass-adherent proteins were detected as round or ellipsoidal patches of autofluorescence under a confocal laser microscope, and visualized ultrastructurally as aggregates of narrow threads of unique loop structures which were composed of linearly aligned particles of 22 +/- 2 nm in diameter. Lithium dodecylsulfate-polyacrylamide gel electrophoresis of the glass-adherent proteins showed two major bands, 12 kDa and 14 kDa, which always co-existed in any different sample. The polyclonal antibody raised against these two proteins specifically stained the glass-adherent proteins in situ. The adhesion of macrophages to glass was significantly blocked with Fab fragments of the antibody. The in situ cross-linking experiment suggested that these two proteins might be closely associated with each other to form complexes. Hence, these proteins can be reasonably considered to be responsible for non-specific adhesion of macrophages to glass.