| Objective and SignificanceSurgical technology continues to progress and the generation of new immunosuppressive agents, kidney transplantation has become the most effective way of clinical treatment of renal failure. Acute rejection is a common complication after renal transplantation, which is also one of the important risk factors that lead to loss of graft function and long term survival of allogaft. Rejection is sorted to cellular rejection and humoral rejection, cellular immunity plays an important role in renal rejection, but the humoral immune rejection also plays a very important role in renal transplant recipients. It is believed that antibodies agaist the human histocompatibility antigen (HLA), which is closely related to renal transplantation rejection reactions and graft survival, especially the antibody for the donor-specific in the pre-transplant recipient, which can cause hyperacute rejection. However, even if HLA genes between donor and recipient match exactly, and renal transplantation rejection may still occur. Therefore, it is recognized that some non-HLA antibodies can also cause to humoral rejection. MIC gene is located on human chromosome6, the2Mb length region of a gene family across the human histocompatibility complex (MHC-I) class, this family showed some homology with classic of HLA-Class Ⅰ gene, but the molecular structure and functions are different from MHC-Ⅰ products, including MICA, MICB, MICC, MICD, MICE, MICF6, of which only MICA and MICB encoding and transcription. MIC gene encoding the product with383-389amino acid residues, contains three extracellular domains (α1, α2, α3), α1and α2formation of the antigen binding site. The MIC genes encoding the products combined with NKG2D molecules, not with the T cell receptor (TCR), is independent of β2-m or transporter associated with antigen processing (TAP). MICA gene is highly polymorphic, and found at least61alleles, the polymorphism is mainly reflected in exon3,4,and microsatellite sequence of transmembrane region. Classic HLA-I molecules are widely distributed in the body cells, but MICA gene is mainly expressed in epithelial cells and fibroblasts, intestinal epithelial cells, also expressed in most epithelial tumor cells (gastric cancer, lung cancer, etc.) combining with surface NKG2D/DAP10receptor of activation of macrophages, CD8+T cells and NK cells and activing cell-mediated cytotoxicity, induced the synthesis of INF-γ and other cytokines, and destruction of graft function. MICA genes have significant racial differences in the polymorphism of MICA in Caucasian MICA008gene most frequently (53%), MICA002(13%), MICA009(3%), the Japanese MICA008gene frequency (30.8%), MICA009(16.5%), MICA007rarely. MHC class Ⅰ-related chain A antigens (major histocompatibility complex class Ⅰ-related chain A, MICA) as the current non-HLA antigens of the highly polymorphic glycoprotein antigen, which is related to cellular and humoral immune responses. MICA antigens may play a role in transplant rejection through the activation of antibody-mediated or cell-mediated immune responses. Hankey, etc. detecting transplanted kidney or pancreas tissue MICA gene expression by immunohistochemistry in all acute tubular necrosis (ATN) and acute rejection in patients. MICA genes don’t express in normal kidney tissue. suggesting that cell surface expression of MICA gene associated with graft damage. MICA antigens as a polymorphism antigen can induce renal transplantation patients to produce specific antibody. Research has shown that many well HLA matched patients is higher than with a poor HLA matched patients about the rate of acute rejection response and long-term chronic graft vascular disease, although most of the occurrence of rejection in kidney transplant recipients produce HLA antibodies, However,1/3patients that do not produce HLA antibodies included MICA antibodies when renal acute rejection occurred.2005KazuoMizutani, et al. found MICA antibodies in rejection kidney dialysis eluent and MICA antibodies are associated with graft function and survival, also involved in the rejection process, suggesting that MICA antibodies may affect graft survival,2007Arundhati, et al. retrospectively studied serum specimens of185patients after renal transplantation and found that the MICA antibody-positive patients with AR rate was33%, MICA antibody-negative group AR rate was14%(P=0.03). The above studies have demonstrated that MICA antibodies rejection reactions correlated significantly with graft loss. MICA antibodies and renal transplantation is more worthy of attention. This topic on the MICA antibody specificity in the reipients waiting for a kidney transplant and preoperative MICA antibodies are impact on acute rejection and renal function after renal transplantation.The first part of study, analysis of MICA antibodies specifity in patients waiting for renal transplantation.Materials and MethodsA total of197renal transplant candidates were enrolled in this study. MICA antibodies and their specificity were dectected in all the patients, MICA fluorescent microspheres were given by Professor Zou Yizhou, coating antigen of MICA001, MICA002, MICA004, MICA007, MICA009, MICA012, MICA017, MICA018, MICA019, and MICA027.By Luminex flow cytometry, add serum into MICA antigens known fluorescent microspheres, then add R-phycoerythrin (PE) labeled goat anti-human IgG, resuspend fluorescent microspheres, read on Luminex machine. Using the Data Collector Versionl.7software for data acquisition, each color laser to read the MICA antigens were>100microspheres, obtain PE fluorescence intensity by molecular cut-off scores and interpret of the0,2,4,8, the OD value of≥4as the MICA antibodies, access to MICA antibody specificity. According to MICA antibodies, they were divided into MICA antibody positive (+) group and MICA antibodies (-) group. Calculate the frequency of specific MICA antibodies in MICA antibodies positive group,(a specific antibody frequency-number of occurrences of the specific antibody/total number of specific antibodies) and monospecific antibodies and multispecific antibodies accounted by the percentage in all MICA antibody-positive reipients.Results197preoperative renal transplant recipients, of45detected MICA antibody positive, whose positive rate was22.84%. MICA antibody detection, respectively:1case MICA007,027;1case MICA001,002,007,012,017,018,019;1case MICA001;2cases for WeakMICA001;4patients for WeakMICA019;1case of MICA007, weak027;1case of MICA019;1case of MICA019,027, weak004,009;1case of MICA001, weak019;1case of MICA002,019;2cases of MICA002,018,007,019,001,012,017,015,027,004,009;1case of MICA019,027,004,009,002,007,018;1case of MICA001,018,004,009,027;1case of MICA001,018,012;2cases of MICA027,009,004;1case of MICA027,009,004,019;1case of001,002,018,027;1case of004,009,027,019,007,018;1case of MICA007;1case f MICA015;1case of MICA002,018,019.18cases with monospecific MICA antibody,17cases including specificity of MICA antibodies (specific antibodies≥2). Antibody frequency of MICA019was65.7%(23/35), MICA027antibody frequency was34.3%, MICA001antibody frequency was28.6%, MICA004,009,018antibody frequency was25.7%, MICA007antibody frequency of22.9%, MICA002antibody frequency was20%, MICA012antibody frequency was11.4%, MICA015017antibody frequency was8.6%. MICA019,027,001,004,009,018antibodies were common.18patients with positive MICA antibodies were single-specific and17were polyspecific (51.4%vs48.6%).The second part of study, the correlation of MICA antibodies and after renal transplantation.Materials and MethodsA total of197renal transplant candidates were enrolled in this study. of which139patients were followed up for early acute rejection (AR) and graft function after transplantation. By Luminex flow cytometry, add serum into MICA antigens known fluorescent microspheres, then add R-phycoerythrin (PE) labeled goat anti-human IgG, resuspend fluorescent microspheres, read on Luminex machine. Using the Data Collector Versionl.7software for data acquisition, each color laser to read the MICA antigens were>100microspheres, obtain PE fluorescence intensity by molecular cut-off scores and interpret of the0,2,4,8, the OD value of≥4as the MICA antibodies, access to MICA antibody specificity. According to MICA antibodies, they were divided into MICA antibody positive (+) group and MICA antibodies (-) group. Collected139transplant recipients’age, gender, postoperative immune suppression scheme, early acute rejection (AR), serum creatinine and24-hour urine within postoperative7days, graft function recovery time etc. in both groups. They were compared between the two groups. Treatment of acute rejection:give methylprednisolone (MP) pulse therapy, the dose was0.5g,0.25g,0.25g,3d consecutive. If no significant improvement in renal function or continue to deteriorate, use CTX pulse therapy,3-5d consecutive. Statistical Methods:Data were processed using statistical software SPSS13.0, measurement data were compared with independent-samples t test, count data were compared with χ2test, correction χ2test or Fisher exact test, P<0.05indicated significant difference.ResultsDonor and recipient with ABO blood well matched, preoperative lymphocytotoxicity test negative. Postoperative immunosuppressive agents are: anti-thymocyte globulin (ATG)+tacrolimus (Tac)+mycophenolate mofetil (MMF)+prednisone (Pred). Transplant recipients age, gender and other factors between the two groups was no significant difference (P>0.05).139patients received renal transplants in197candidates, of which39occurred the early AR(28.1%).38of45positive MICA antibodies received renal transplants,14occurred the early AR(36.8%);101of152negative MICA antibodies underwent renal transplantation,25occurred the early AR(24.8%). There is no significant differences in the early AR rate between the positive MICA antibody group and negative group.4of18cases of monospecific antibodies occurred early AR (AR rate of22.2%),7of17cases of multispecific antibodies occurred early AR (AR rate of41.2%), the AR rate had differences between the two groups, but the difference was not statistical significance (χ2=1.46, P>0.05). While the professor Zou reported that254recipients with immunosuppressive drugs effective concentration treatment and postoperative MICA antibody positive rate was13.4%, significant differences between the two groups (x2=6.867, P=0.009<0.01).Postoperative follow-up38positive MIICA antibodies reiciepients,7cases of which result in data loss due to their inability to obtain the information of serum creatinine, serum creatinine (CR) of31known information MICA antibody-positive recipients, to participate in the MICA antibody-negative patients were followed up by101cases,19of which lead to data loss due to inability to get the cases of serum creatinine data, CR of82known data MICA antibody-negative recipients. The postoperative1week serum creatinine difference was not statistically significant (F=0.001, P=0.979>0.05), indicating the group effect of serum creatinine after1week at different times was the same; timing differences of two groups are statistically significant differences (F=216.053, P=0.000<0.05), indicating that there are differences between the serum creatinine level at different times after transplant. There are no interaction effects in time and group factors (F=0.797, P=0.363>0.05), suggesting that group differences did not change with the time, suggesting that there are no statistically significant differences between the two groups about serum creatinine;24hour urine of31known data MICA antibody-positive recipients was after posttransplants, and20cases who can not get cases of urine data,24hour urine of known information81MICA antibody-negative recipients in the postoperation. The postoperative1week24hour urine difference was not statistically significant (F=0.006, P=0.940>0.05), indicating the group effect of24hour urine after1week at different times was the same; timing differences of two groups are statistically significant differences (F=49.654, P=0.000<0.05), indicating that there are differences between the24hour urine level at different times after transplant. There are no interaction effects in time and group factors (F=0.122, P=0.947>0.05), suggesting that group differences did not change with the time, suggesting that there are no statistically significant differences between the two groups about24hour urine; graft function recovery time of38patients with MICA antibody-positive recipients was (18.1±19.1) days,5of101MICA antibody-negative recipients lack of recovery time data, graft function recovery time of known information96MICA antibody-negative recipients was (13.6±15.0) days, there was no statistical differences between the two groups.(t=1.323,P=0.191>0.05).9of18monospecific MICA antibodies reicipients were not able to obtain serum creatinine data, CR of known information9monospecific MICA antibodies reicepients was (202.9±130.2) umol/L in postoperative the7th day,3of17multispecific MICA antibodies reicipients were not able to obtain serum creatinine data, CR of14known data mutispecific MICA antibodies was (193.3±135.9) umol/L in the postoperative7th day. there was no statistical differences between the two groups (t=0,168,P=0.868>0.05);24hour urine of9of18known information monospecific antibodies was (2752.8±594.6) mL in the postoperative7th day.24hours of14known information multispecific antibodies recipient was (2838.1±698.0) mL in the postoperative7th day. there was no statistical differences between the two groups (t=-0.302,p=0.765>0.05); Graft function recovery time of12information known monospecific antibody group was (14.0±14.2) days, which of17multispecific antibody group was (20.0±21.5) days, there was no statistical differences between the two groups (t=-0.804,P=0.407>0.05).ConclusionsMICA019antibody frequency was65.7%in the MICA antibodies, which showed MICA019was a common gene in the population for high frequency. The ratio of antibodies with single-specific and polyspecific was close (51.4%vs48.6%), suggesting that the production of MICA antibodies might not via a single pathway, a variety of factors and mechanism of antibody production should be further discussed in detail. Although there is no significant differences in the early AR rate between the positive MICA antibody group and negative group, Pretransplant MICA antibodies had an independent effect on increasing early AR rate post-transplant(28.1%↑36.8%,24.8%↑36.8%), the increasing range in early AR rate was from8.7%to12%of clinical significance. The study also found that there is significant difference between Zou survey of254cases waiting for a kidney transplant within the scope of the effective concentration of MICA antibody positive rate of13.4%and197cases of preoperative MICA antibody positive rate of22.84%, suggesting that the immune suppression drugs can inhibit MICA antibodies. |
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