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Receptor‐Mediated Endocytosis of Carcinoembryonic Antigen by Rat Alveolar Macrophages In Vitro
Author(s) -
Toth Carol Ann,
Rapoza Alan,
Zamcheck Norman,
Steele Glenn,
Thomas Peter
Publication year - 1989
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.45.4.370
Subject(s) - endocytosis , in vitro , receptor mediated endocytosis , alveolar macrophage , biology , carcinoembryonic antigen , microbiology and biotechnology , pulmonary alveolus , receptor , macrophage , antigen , a549 cell , biochemistry , immunology , genetics , cancer
Uptake of carcinoembryonic antigen (CEA) by isolated rat alveolar cells was time, temperature, and concentration dependent (K uptake , = 2.4 × 10 ‐7 M). Pretreatment of the alveolar cells with colchicine inhibited internalization of CEA. Uptake of 125 Mabeled CEA by alveolar cells required divalent cations and was inhibited by cold CEA and nonspecific cross‐reacting antigen (NCA). The carbohydrate portion of CEA was modified by neuraminidase treatment and Smith degradation. The modified glycoproteins inhibited endocytosis by the alveolar macrophages, thus excluding nonreducing terminal carbohydrate residues as the recognition site of the receptor. Endocytosis of CEA was independent of native protein conformation since performlc acid oxidized CEA and glycopeptides produced by pepsin digestion were inhibitory. Rat alveolar macrophages bound CEA with similar specificity to that of rat Kupffer cells. Alveolar macrophages, unlike Kupffer cells, did not rapidly exocytose the internalized CEA. Neither P388D 1 , a macrophage‐like murine cell line, nor murine peritoneal exudate cells were capable of endocytosing CEA in vitro.