Analysis Of Natural Killer Cell Immunoglobulin-like Receptor (KIR) Gene In Uremic Patients

BackgroundRenal allograft survival with modern immunosuppressive agents is high, with some units achieving more than 90% at 1 year. However, acute rejection still occurs and it frequently leads to permanent graft dysfunction or graft loss. The success of organ transplantation depends on the prevention of acute rejection. T and B lymphocytes form the major component of the cellular and humoral arms of the rejection response, respectively, and have been extensively studied. The importance of natural killer (NK) cells in transplantation has become an increasing area of interest as reagents for their study have become available. NK cells have the ability to destroy cells with abnormal HLA class I expression and may play a previously unrecognized role in solid organ transplantation. NK cells form part of the innate immunity, forming a crucial first line of defense against foreign antigens. They do not require priming and are able to kill target cells independently. The peak of NK activity occurs within 3 days of the initiation of the response, before T-cell activity reaches maturation. They have an established role in defense against tumors, viral infection, and the rejection of bone marrow transplant. Their importance in solid organ transplantation has recently been demonstrated in animal models of allotransplantation. In the human, increased numbers of circulating NK cells have been demonstrated during acute rejection of renal allograft and they have been shown to infiltrate cardiac and renal allografts. NK cells have the ability to lyse human renal epithelial cells in vitro. Using a panel of monoclonal antibodies directed against various leukocyte markers, CD56+ NK cells had been shown to infiltrate renal allografts during early rejection, followed by an influx of T cells and macrophages.The polymorphic family of killer-cell immunoglobulin-like receptors (KIRs) consists of activating and inhibitory receptors expressed by natural killer (NK) cells and effector T cells that recognize human leukocyte antigen (HLA) classⅠligands. KIR are the best studied group of activating and inhibitory receptors that control NK-cell function. Genes coding for them are found on chromosome 19ql3.4, is transmembrane glycoprotein, which has two or three extracellular immunoglobulin-like domain, respectively KIR2D and KIR3D. According to the different KIR cytoplasmic domain can be divided into L (inhibitory) receptors control the inhibitory effect of NK cell function and S (activated) receptors control NK cell function in activating effect.Inhibitory KIR have long cytoplasmic domain,such as KIR3DL1 with three immunoglobulin like domain and contain immunoreceptor tyrosine-based inhibitory motif(ITIM)and activatory receptor KIR3DS1, its transmembrane domain has with positive charge residue that can bind specificity junct protein, no ITIM. Each human NK cell can express several KIR. On binding their specific ligands, KIR recruit phosphatase enzymes by means of characteristic motifs in their cytoplasmic tails (immunomodulatory tyrosine inhibitory motifs [ITIM]), preventing the phosphorylation events associated with cellular activation. However, isoforms of these molecules, which lack ITIM motifs, can stimulate cellular functions through association with a linker molecule that contains the activating motif (ITAM) necessary to initiate effector mechanisms. Under normal circumstances, inhibitory signals override the activating signals to inhibit the killing of autologous cells, thereby avoiding autoimmunity. However, tumor cells and cells infected by viruses may have an altered or lower level of class I MHC molecules; this may result in NK cytotoxicity because of a lack of inhibitory signals. We hypothesize here that allogeneic cells will be subjected to NK-cell killing if their class I MHC molecules are not recognized by the recipient's inhibitory receptors. Killer immunoglobulin-like receptors (KIR), the best characterized group of NK receptors, are allotype and isotype specific. For example, KIR 2DL1 binds only to group 2 human leukocyte antigen (HLA)-Cw (Ser77, Asn80) and KIR 2DL2 binds only to group 1 HLA-Cw (Asn77, Lys80) molecules. Thus, allografts with mismatched HLA molecules can potentially be recognized and killed. Natural killer (NK) cells use killer immunoglobulin-like receptors (KIR) that bind to self-class I major histocompatibility complex (MHC) molecules to prevent killing of autologous cells. Mismatched allografts, which do not express recipient MHC class I molecules, can therefore be potential targets for NK-cell killing. In our living related-unrelated renal transplantation program, donor-recipient pairs vary in the amount of both HLA and KIR genes they share. This provides us with a unique opportunity to dissect the influence of KIRon NK-cell function after transplantation.This article is intended to investigate the express of KIR gene frenquencies of killer cell immunoglobulin-like receptor in uremia patients (potential kidney transplant recipients),analyzing the distribution of KIR gene frequencies,as well as the association to the disease.Objective To investigate the express of KIR gene frenquencies of killer cell immunoglobulin-like receptor in uremia patients.Methods 102 uremia patients were chosen to drawn venous blood According the KIR basic radical coded sequence that publication by IDP KIR sequence library(www.ebi.ac.uk/ipd/kir) on November 10,2006 (release 1.3.0).Twenty-three pairs of primers were designed, whole were verification by BLAST software, which can recognize 16 KIR genes, contains 14 functional genes and 2 silent genes. In our study,102 uremia patients who waiting for kidney transplantation. polymerase chain recation-sequences specific primer (PCR-SSP) was used to Analysis the KIR gene frenquencies, which compared with HongKong Chinese, Singapore Chinese,Korean and Japanese.Results Sixteen KIR genes were observed in uremia patients, contains 14 functional genes (2DL1,2DL2,2DL3,2DL4,2DL5,3DL1,3DL2,3DL3,2DS1,2DS2,2DS3,2DS4,2DS5,3DS1)and 2 silent genes (2DP1,3DP1)The frequencies(GF)of KIR-3DL2,3DL3,3DP1 are 1.00; 2DL1,2DL3,2DL4,3DL1 are 0.73～0.90; 2DS4,2DP1 are 0.61-0.69; 2DL2,2DL5,2DS1,2DS2,2DS3,2DS5,3DS1 are 0.10～0.22. Compared the frequencies of uremia patients with ethnic Chinese of other Asian coutries and regions,14 functional KIR genes frequencies are basically close to which of Chinese population in HongKong.In addition to 2DL3(p=0.09),compared with Singapore Chinese, difference of the 13 KIR gene frequencies were less than 0.20. This is detected KIR-2DL2,2DL3, and 2DS2 gene frequency in our study with South Korea, and Japan difference between groups was statistically significant (P<0.05).Conclusions All 16 known genes observed in uremia patients indicated that the KIR genes are polymorphic.102 cases ueder investigation with the framework gen3DL2,3DL3,3DPl,followed by 2DL1,2DL3,2DL4,3DL1,2DS4,rare fThe most frequent genes were 2DL4,3DL2,3DL3 and 3DP1; followed by 2DL1,2DL3,3DL1 and 2DS4; rare for the 2DS3,2DL2,2DS1,2DS2.2DS3 and 2DS5. This study showed that the expression of KIR-2DL3 in uremia patients are less than other healthy people,and there is a high concordance but variability in the frequent distributions of KIR gene among the uremia patients and other non-Chinese populations.