Abstract 1357: Role of Natural Killer-cell Immunoglobulin-like receptors KIR2DL1 and KIR3DL1 in immune resistance
Authors: Chan Daniel C. , Zhang Zhiyong , Wang Hong , Sui Xiaomei , Chan Tiffany T. , Ahn Natalie , Lanier Lewis L. , Bunn Paul A. 
Published: February 2011

Abstract
Background: The aim of this study is to investigate the mechanism of immune-escape and cancer metastasis by the natural killer (NK) cell immunoglobulin-like receptor (KIRs) subtypes (KIR2DL1 and KIR2DL1) in human lung cancer. We previously reported that metastatic cancer cells acquire immune-resistance by aberrantly expressing KIR on their surface (AACR 2009). In this project we forced expression two of KIR2DL1 and KIR3DL1 plasmids in some H2122-GFP parental lung cancer cells with null expression of KIR and investigated their function in conferring the immune-resistance against NK cell killing.
Method: KIR2DL1 (LL454) and KIR3DL1 (LL456) plasmids were transfected into Phoenix Retroviral Expression system. Virus containing media were used to infect target cells (H2122-GFP) for individual KIR subtype or both KIR subtype expression. Stable transformants were enriched by cell sorting. H2122-GFP parental cells and KIR expressing cells were exposed to various amounts of human normal NK cells or transformed NK-92MI cell line. Anti-proliferative effects by NK cells were accessed with fluorescence intensity in microplate reader. IC50 was determined based on the Effector (NK) / Target Ratio (ETR).
Result: Using cell sorting, single (2DL1 or 3DL1) or double (2DL1 and 3DL1) KIR expressing cells were separated into groups of low, medium and high level of KIR2DL1 or KIR3DL1 expression, based on their fluorescence intensity. When exposed to various amount of normal human NK cells, the parental line was most sensitive to NK killing with an IC50 ETR=2.2, followed by 2DL1-M (4.7), 3DL1-M (5.2), 2DL1-H (7.0), 3DL1-H (9.5), KIR2+ (10.1) and KIR3+(12). Interestingly, the transformed NK-92MI cell line seemed to be more effective than normal human NK cell in killing H2122-GFP and its derivatives and had down shifted the ETR by 10 fold. Nevertheless, the parental line was most sensitive to NK-92MI killing with an IC50 ETR = 0.23, followed by 2DL1-H (0.66), 3DL1-H (1.1), 3D/2DL1-L (1.5), KIR3+(1.8), 2D/3DL1-M (2.00), 2D/3DL1-L (2.20), 3D/2DL1-H (2.60), 3D/2DL1-M (2.90) and 2D/3DL1-H (3.0) respectively. Our data clearly demonstrated that forced expression of KIRs into lung cancer cells confers resistance to NK cytolytic killing and the degree of resistance increases progressively with the level of KIR expression. Double expression of both 2DL1 and 3DL1 in high level in lung cancer cells resulted in higher resistance than the metastatic KIR+3 line.
Conclusion: Aberrant expression of KIR, either by in vivo immune-selection or by forced expression, is responsible for conferring immune-resistance against NK cytolytic killing of human lung cancer cells.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1357.