Differential expression of membrane sialoglycoproteins in exudate and resident mouse peritoneal macrophages

Wheat germ agglutinin (WGA) has been used to define biochemical differences between exudate and resident macrophages in the peritoneal cavity of mice. Western blotting with 125I-WGA identifies a restricted set of glycoproteins in elicited peritoneal macrophages (M phi) (recruited with thioglycollate or periodate) and fully activated M phi (recruited with live Bacille Calmette-Guérin, or heat-killed Corynebacterium parvum); the major species migrates with Mr 89-115 kDa in 10% acrylamide gels. These glycoproteins are not detected in resident peritoneal M phi, nor in thymocytes, neutrophils, lymphocytes and a variety of non-M phi cell lines. The binding of WGA is sensitive to neuraminidase, which exposes binding sites on these proteins for peanut agglutinin and reduces their electrophoretic mobility; these features are typical of O-linked sialo-oligosaccharides. In culture, exudate M phi increase their WGA-binding content over 48 h, and continue to display a phenotype distinct from that of resident peritoneal M phi. The stable differential expression of these sialoglycoproteins, by elicited and activated versus resident peritoneal M phi, suggests that biochemical modification during the synthesis and expression of membrane glycoproteins accompanies M phi recruitment to an inflammatory focus.