Retinoic acid treated HL60 cells express CEACAM1 (CD66a) and phagocytose Neisseria gonorrhoeae

Neisseria gonorrhoeae (gonococci, GC) are phagocytosed by neutrophils through the interaction between opacity proteins (Opa) and the CEA (CD66) family of antigens. In order to study this interaction, we used the human myeloid leukemia HL60 cell line, which differentiates into granulocyte-like cells upon treatment with dimethylsulfoxide (DMSO) or retinoic acid (RA). We found that RA-, but not DMSO- or untreated-FIL60 cells, can phagocytose Opal-expressing gonococci as well as Escherichia coli. The interaction of Opal E. coli with RA-treated HL60 cells was inhibited by antibodies against CEACAM1 Phagocytosis of Opal E. coli was found to be a result of the expression of CEACAM1 in RA-treated HL60 cells. Our results indicate that the level of expression of CEACAM1 in HL60 cells can be regulated by treatment with RA in a differentiation-dependent manner, and that this is important for phagocytosis of Opal-expressing gonococci or E. coli. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.