EXPRESSION OF FUCOSYLATED ANTIGENS AND ALPHA-1,3 FUCOSYL-TRANSFERASESIN HUMAN LEUKEMIA-CELL LINES

The expression of alpha 1,3 fucosylated type 2 antigens is generally t hought to be restricted to myeloid cells among normal human haemopoiet ic tissue. The distribution of three fucosylated antigens [Lewis X (Le (x)), sialyl Lewis X (sLe(x)) and VIM2] was investigated among nine hu man leukaemia cell lines by fluorescence activated cell sorting (FACS) analysis. As expected, all myeloid cell lines were positively stained by antibodies against these three fucosylated antigens. Unexpectedly, two T-lymphocytic cell lines (CCRF-CEM and MOLT4) were found to expre ss Le(x) and VIM2, and the plasma, B-cell line, RPMI 8226, expressed a ll three fucosylated antigens. Enzymatic and RNA analyses [Northern bl ot and reverse transcription polymerase chain reaction (RT-PCR)] were used to evaluate possible control points in the biosynthetic pathway f or Le(x) and sLe(x). beta 1,4 Galactosyltransferase (beta 1,4GalT, an enzyme involved in the synthesis of the core oligosaccharide of the th ree fucosylated antigens) activity and the corresponding mRNA were fou nd in an of the leukaemia cell lines, regardless of whether or not the y expressed the fucosylated antigens. In contrast, alpha 1,3 fucosyltr ansferase (GDP-fucose:beta-D-N-acetylglucosaminide 3-alpha-L-fucosyltr ansferase; alpha 1,3FT) activity and the corresponding mRNA were found only in those cell lines expressing fucosylated antigens. Based on RN A analysis, acceptor specificity and N-ethyhnaleimide inhibition studi es, it was concluded that all of the cell lines expressing fucosylated antigens contained alpha 1,3FTIV (myeloid alpha 1,3FT). This appeared to be the major alpha 1,3FT in the myeloid and T-lymphocytic cell lin es. Interestingly, even though both types of cell lines expressed the same alpha 1,3FT, only the myeloid cell lines expressed sLe(x), wherea s all of the myeloid and T-lymphocytic cell lines expressed a structur al analogue of sLe(x) (i.e. VIM2). In contrast to the myeloid and T-ce ll lines, RPMI 8226 cells contained more than one fucosyltransferase a ctivity. Acceptor specificity analysis demonstrated that this cell lin e contains alpha 1,3 and alpha 1,4FTs. Among the fucosyltransferases e xpressed by RPMI 8226, alpha 1,3FTIV accounted for only a small amount of the total activity. The results of this study demonstrate that fuc osylated antigens, which are generally considered to be myeloid specif ic antigens, are also expressed by lymphocytic leukaemia cell lines, a nd that the types of fucosylated antigens and fucosyl-transferases exp ressed in these cell lines vary.