Studies on the susceptibility to NK-mediated lysis and the simultaneous expression of various surface molecules in anthracyclin-treated K562 cells and in four K562 cell clones

Abstract

Target molecules for NK cells are unknown. Numerous studies have proposed putative target molecules, but have examined their role in the modulation of sensitivity to NK-mediated lysis one independently of each other. We examined the simultaneous expression of various surface molecules and the susceptibility of K562 cells to NK attack. We have previously shown that adriamycin (40 nM) and aclacinomycin (15 nM) can induce, in vitro, an increase of glycophorin A (GPA) on K562 cells, a modulation of transferrin receptor (TfR) and CD15 antigen expression and a significant resistance of cells to NK-mediated lysis. In the present work, Fc gamma receptor II (CD32) expression at the K562 cell membrane was clearly decreased after aclacinomycin-treatment but was unaltered by adriamycin-treatment. Four K562 cell clones were studied. Two clones (F and G) expressed a higher level of CD32 at the membrane (62% and 70% of erythrocyte antibody (EA) rosettes respectively) and two clones (9 and 19) expressed lower a level (18% and 7% EA rosettes respectively) than the original population (43%). The sensitivity to lysis by NK cells was increased in clones F, G and 9 but decreased in clone 19 (without alteration in the binding capacity). Relationships between the sensitivity to NK attack and the levels of simultaneous expression of CD32, TfR, CD15, glycophorin A (GPA) and MHC class I monomorphic antigens were studied. In addition, the presence at the membrane of some cellular adhesion molecules (CD54, CD58, CD29, CD18, CD56) was examined in anthracyclin-treated cells and in the four clones. The difference in the sensitivity of target cells to NK attack is not strictly related to variation of one or other of these molecules. Our previous and present data suggest that the resistance of K562 cells to NK cells may correlate with the level of erythroid maturation at the cell membrane, involving simultaneous variations in expression of several molecules such as a decrease of TfR, CD15 and CD32 and an increase of GPA.