A study of the effect of enhancing NK mediated tumour cytotoxicity by the manipulation of both the effector and target cell populations in vitro

Natural killer (NK) cells are a subset of T lymphocytes with the phenotype CD3, CD16+, CD56+ and are capable of mediating tumour cell cytolysis. The purpose of this study was therefore to investigate the role this lymphocyte subset plays in tumour cytotoxicity.;Characterisation of NK mediated K562 cytotoxicity was assessed using PBMC from 21 young healthy donors, 19 elderly healthy donors and 22 cancer patients. No correlation was found between age (or sex) and K562 cytotoxicity however NK cell number correlated significantly with levels of NK cytotoxicity. The effect of various mAb (anti-CD3 (T3 and OKT-3) and anti-CD16) on NK cytotoxicity was examined. The mAb's T3 and anti CD16 mAb significantly enhanced NK cytotoxicity in vitro.;Insertion of MHC and Interferon genes into tumour target cells was carried out to examine the effect of target cell modification on NK cytotoxicity.;After ascertaining a means to viably transfect the target cells with the appropriate genes, NK assays were carried out to determine any increase in cytotoxicity both with and without the addition of activating antibodies. The colo-rectal lines were not found to be significantly susceptible to NK killing by the insertion of any of the genes. The DR4- transfected K562 line showed a 150% increase in susceptibility to NK killing over the untransfected parent line. This percentage increased to 160% when the NK cells were pre-stimulated with T3 mAb. Finally the addition of the DR4- gene did not cause a significant increase over the percentage rise observed with just the alpha gene.;It was therefore found that the NK activity of cancer patients was lower than that of healthy individuals. NK anti tumour activity was dramatically increased using the T3 monoclonal antibody and transfection of the K562 cell line with DR alpha chain brought about a significant increase its immunogenicity against NK cells which was further heightened when the NK cells were pre-incubated with the T3 antibody.