CGM1a antigen of neutrophils, a receptor of gonococcal opacity proteins.
Neisseria gonorrhoeae (GC) or Escherichia coli expressing phase-variable opacity (Opa) protein (Opa+ GC or Opa+ E. coli) adhere to human neutrophils and stimulate phagocytosis, whereas their counterparts not expressing Opa protein (Opa- GC or Opa- E. coli) do not. Opa+ GC or E. coli do not adhere to human lymphocytes and promyelocytic cell lines such as HL-60 cells. The adherence of Opa+ GC to the neutrophils can be enhanced dramatically if the neutrophils are preactivated. These data suggest that the components binding the Opa+ bacteria might exist in the granules. CGM1a antigen, a transmembrane protein of the carcinoembryonic antigen family, is exclusively expressed in the granulocytic lineage. The predicted molecular weight of CGM1a is approximately 30 kDa. We observed specific binding of OpaI+ E. coli to a 30-kDa band of polymorphonuclear leukocytes lysates. To prove the hypothesis that the 30-kDa CGM1a antigen from neutrophils was the receptor of Opa+ bacteria, we showed that a HeLa cell line expressing human CGM1a antigen (HeLa-CGM1a) bound Opa+ E. coli and subsequently engulfed the bacteria. Monoclonal antibodies (COL-1) against CGM1 blocked the interaction between Opa+ E. coli and HeLa-CGM1a. These results demonstrate that HeLa cells when expressing the CGM1a antigens bind and internalize OpaI+ bacteria.
Chen
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Laboratory of Bacterial Pathogenesis and Immunology, Rockefeller University, New York, NY 10021, USA.
Gotschlich
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D000942:Antigens, Bacterial / Q000378:metabolism*; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D002272:Carcinoembryonic Antigen / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D004926:Escherichia coli; D006367:HeLa Cells; D006801:Humans; D009504:Neutrophils / Q000378:metabolism*
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; C075729:CEACAM3 protein, human; D002272:Carcinoembryonic Antigen; D015815:Cell Adhesion Molecules; C050308:opacity proteins