[Frontiers in Bioscience E3, 166-178, January 1, 2011]

KHYG-1 and NK-92 represent different subtypes of LFA-1-mediated NK cell adhesiveness

Garnet Suck1, Suet-Mien Tan2, Sixian Chu1, Madelaine Niam1, Ardcharaporn Vararattanavech2, Tsyr Jong Lim1, Mickey B. C. Koh1,3

1Blood Services Group, Health Sciences Authority, 11 Outram Road, Singapore,169078, 2School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, and 3Department of Haematology, St. George's Hospital and Medical School, Blackshaw Road, London, SW17 0PE, UK

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Materials and methods
3.1. Cell lines and culture
3.2. NK cell and peripheral blood lymphocyte (PBL) isolation and culture
3.3. Reagents
3.4. ICAM-1 and ICAM-3 binding assays and imaging
3.5. Microscopic analyses: effector-target contact
3.6. Flow cytometry
3.7. Flow cytometric cytotoxicity assay
3.8. Statistical analyses
4. Results
4.1. Long-term IL-2 stimulated NK cells/ cell lines have superior cytotoxicity
4.2. LFA-1 is constitutively activated in NK effectors
4.3. ICAM-1 binding induces cell spreading in KHYG-1, but not in NK-92 and partially in long-term IL-2 activated primary NK cells
5. Discussion
6. Acknowledgements
7. References

1. ABSTRACT

Novel cancer cellular therapy approaches involving long-term ex vivo IL-2 stimulated highly cytotoxic natural killer (NK) cells are emerging. However, adhesion properties of such NK cells are not very well understood. Herein, we describe the novel observation of permanently activated alphaLbeta2 integrin leukocyte function-associated antigen (LFA)-1 adhesion receptor in long-term IL-2 activated NK cells and the permanent NK cell lines KHYG-1 and NK-92. We show that such cytokine activated NK effectors constitutively adhered to the LFA-1-ligand ICAM-1, whereas binding to the lower affinity ligand ICAM-3 required additional exogenous activating conditions. The results demonstrate an extended conformation and an intermediate affinity state for the LFA-1 population expressed by the NK cells. Interestingly, adhesion to ICAM-1 or K562 induced pronounced cell spreading in KHYG-1, but not in NK-92, and partially in long-term IL-2 stimulated primary NK cells. It is conceivable that such differential adhesion characteristics may impact motility potential of such NK effectors with relevance to clinical tumor targeting. KHYG-1 could be a useful model in planning future targeted therapeutic approaches involving NK effectors with augmented functions.