The role of KIR positive NK cells in diseases and its importance in clinical intervention.

Natural killer (NK) cells are essential for the elimination of the transformed and cancerous cells. Killer cell immunoglobulin-like receptors (KIRs) which expressed by T and NK cells, are key regulator of NK cell function. The KIR and their ligands, MHC class I (HLA-A, B and C) molecules, are highly polymorphic and their related genes are located on 19 q13.4 and 6 q21.3 chromosomes, respectively. It is clear that particular interaction between the KIRs and their related ligands can influence on the prevalence, progression and outcome of several diseases, like complications of pregnancy, viral infection, autoimmune diseases, and hematological malignancies. The mechanisms of immune signaling in particular NK cells involvement in causing pathological conditions are not completely understood yet. Therefore, better understanding of the molecular mechanism of KIR-MHC class I interaction could facilitate the treatment strategy of diseases. The present review focused on the main characteristics and functional details of various KIR and their combination with related ligands in diseases and also highlights ongoing efforts to manipulate the key checkpoints in NK cell-based immunotherapy.