KIR genotype distribution among patients with multiple myeloma: Higher prevalence of KIR 2DS4 and KIR 2DS5 genes

INTRODUCTION Natural killer (NK) cells possess an antitumor activity against multiple myeloma cells proven by the susceptibility of plasmocytes to NK lysis. In the early stage of MM, the killing of MM cells is mediated by natural cytotoxicity receptors (NRC) and NKG2D-dependent pathway, while in the late stage, NK cells lose their killing potential against MM cells due to the high expression of HLA class I molecules on MM cells. AIM The aim of this paper is to study KIR expression of NK cells in MM patients and in healthy controls, to check for any association between KIR genotypes and MM. METHODS KIR genotype was analyzed in 120 healthy Lebanese individuals and 34 MM patients using the KIR Genotyping SSP kit. RESULTS KIR 2DS4*001/002 and KIR 2DS5 were found to be significantly more prevalent among MM patients as compared to controls. For MM patients, the AA, AB, and BB genotype frequencies were, respectively, 38.23%, 47.06% and 14.71% with an A:B ratio of 1.62:1. As for the healthy controls, the AA, AB, and BB genotype frequencies were, respectively, 39.17%, 50%, and 10.83% with an A:B ratio of 1.80:1. CONCLUSION The interesting observation of the significant presence of KIR2DS4 and KIR2DS5 genes more among multiple myeloma patients than controls is worth further clinical, translational as well as survival research studies in these cases.