Background NKcells play an important role in the elimination of tumors and represent achallenge for research due to their specific effect on tumor cells. It ispossible to examine NK cellular characteristics, as well as the number of cellsand their function.

Materials and Methods In this work, the activity of NK cells against two hematological cell lines wasexamined. NK cell activity was investigated using a radioactive assay based onthe release of radioactive chromium as compared to the level of TNF receptorson target cells. Flow cytometry was used to determine the degree of expressionof molecules on the cell membrane.

Results The findings indicate that the MDS cellline released more radioactive chromium compared to K562 cells, but that thecytotoxic activity of NK cells from healthy subjects was reduced in MDS cellscompared to K562. The data correlate with the level of expression of surfacereceptors from the TNFR1 family (CD120a), which is more expressed on MDS cellscompared to K-562 cells. Polymerase chain reaction (PCR) test shows that bothcells express TNF-alpha, but the expression on the surface is different, which isthe reason for the different response to lytic sensitivity towards NK cells.

Conclusions This is consistent with the fact that NKcell function is the induction of cell death of target tumor cells through theactivation of apoptosis receptors. Bearing in mind that MDS spontaneously decayin culture more than K-562, the fact remains that K-562 is a better target forexamining NK compared to the MDS cell line. Bearing in mind that MDSspontaneously decay in culture more than K-562, the fact remains that K-562 isa better target for examining NK compared to the MDS cell line.

V. Jurisic: None.