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

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Abstract
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-Guerin, 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.