BILIARY GLYCOPROTEIN (BGP) EXPRESSION ON T-CELLS AND ON A NATURAL-KILLER-CELL SUBPOPULATION

Human T and natural-killer(NK) cells, that are thought to be the major cytotoxic effector-cell populations in the defence against neoplastic cells, were isolated from blood and decidua in order to analyze their expression of carcinoembronic-antigen-(CEA)-family-member proteins. B illary glycoprotein (BGP, CD66a) was the only member of the carcinoemb ryonic antigen family detected. While freshly isolated T-cells express ed low amounts of BGP, freshly isolated NK cells were negative. After in vitro stimulation for 3 days, T cells up-regulated their BGP expres sion and a sub-group of NK cells (CD16- CD56+), known to predominate i n decidua, revealed de novo expression of BGP. In contrast, stimulated CD16+ CD56+ NK cells, which occur exclusively in the blood, remained negative. The expression of BGP could be shown on the protein level by using a panel of 12 well-defined MAbs and on the transcription level in rt-PCR and subsequent oligonucleotide hybridization. Interestingly, rIL-2-stimulated T cells expressed 3-fold higher levels of BCP compar ed with those seen after stimulation with phytohemagglutinine (PHA). P HA, on the other hand, induced a higher expression of HLA-DR, an activ ation marker of T cells. The differential regulation implies a distinc t function of BCP and HLA-DR. (C) 1996 Wiley-Liss, Inc.