Monitoring human leukocyte antigen humoral immunity sensitization in renal transplant recipients and its clinical significance

Liuyang LI; Zhanguo LIU; Jianrong CHEN; Jun QIAN; Erwei SUN; Ming ZHAO

ABSTRACT

BACKGROUND:

Panel reactive antibodies (PRA) easily appear in the peripheral blood of organ transplant recipients sensitized by allogeneic human leukocyte antigen (HLA).How to enhance the success rate of renal transplantation.and long-term survival rate of renal allografts in sensitized recipients should be further studied.

OBJECTIVE:

This study was to detecthuman leukocyte antigen immunoglobulin G(HLA-IgG) antibody level and its specificity in renal transplant recipients,evaluate humoral immunity sensitization,and investigate the relationship of the acceptable mismatching of HLA cross-reactive group and survival rate of renal allograft.

DESIGN:

A clinical observation.

SETTING:

Zhujiang Hospital Affiliated to Southern Medical University.

PARTICIPANTS:

A total of 1297 patients,824 males and 473 females,averaging (42±16) years of age,received renal transplantation in the Department of Organ Transplantation,Zhujiang Hospital,Southern Medical University between January 1998 and December 2005,were recruited for this study.Among these patients,165 were HLA-IgG antibody-positive recipients,1132 were HLA-IgG antibody-negative ones,1217 received renal transplantation for the first time,77 received renal transplantation twice,2 three times,and 1 four times.Written informed consent was obtained from each subject for related laboratory measurements and treatment.The protocol was approved by the Hospital's Ethics Committee.ReagentsLamhda antigen tray (LAT),Lambda antigen tray mixed (LATM),Special Monocloneal Tray-Asian HLA Class Ⅰ,and Micro SSP? Generic HLA Class Ⅱ were purchased from One Lambda Company,USA.Taq polymerase was purchased from PE Company,USA. DNA extract reagent was from Qiagen Company,Germany.Anti-human complement 4d (C4d) polyclonal antibody and chrornogenic substrate DAB were purchased from Biomedica Company,Austria.

METHODS:

Prior to operation,serum HLA-IgG antibody in the recipients was determined by an enzyme linked immunosorbent assay (ELISA).HLA-IgG antibody-positive serum was further detected by antigen tray (LAT1240 and LATIHDS) for antibody-positive rate and specificity.HLA genotyping was performed by a sequence specific primer polymerase chain reaction (PCR-SSP).For 40 recipients who had elevated serum creatinine (Scr),anti-HLA antibody detection and renal transplant needle biopsy were conducted.At the same time,C4d deposition on the capillary wall around the renal tubule was observed by immunohistochemical staining.Survival rate of renal allografts in recipients 1,3,and 5 years after transplantation,and relationships of gender and renal transplantation and antibody-positive rate were investigated.Survival rate of renal allograft in recipients that received different mismatch of HLA cross-reactive group was analyzed.MAIN OUTCOME

MEASURES:

Prior to and after renal transplantation,HLA-IgG antibody-positive rate and HLA genotyping in renal transplant recipients.Characterization of C4d deposition on the capillary wall around the renal tubule in the renal transplant biopsy tissue.Difference of survival rate of renal allograft.

RESULTS:

All 1297 recipients were included in the final analysis.Among them,1132 were HLA-IgG antibody-negative recipients,165 were HLA-IgG antibody-positive ones,126 were anti-HLA class Ⅰ IgG antibody-positive ones,90 were anti-HLA class Ⅱ IgG antibody-pesitive ones,51 were anti-HLA class Ⅰ and Ⅱ IgG antibody-positive ones,and 94 were highly sensitized ones (antibody-positive rate ＞50%).Among 40 recipients with needle biopsy,C4d deposition was found in the 13 recipients,but not found in the 27 recipients.Ten out of thirteen C4d-positive recipients presented with anti-HLA antibody-positive in the peripheral circulation.The incidence for delayed graft function (DGF) was significantly higher in recipients with HLA-IgG antibody-positive than in recipients with HLA-IgG antibody-negative (P ＜ 0.01).There was no significant difference in the survival rates of renal allografts between recipients with HLA-IgG antibody-positive and with HLA-IgG antibody-negative 1 ,3,and 5 years after renal transplantation (P ＞ 0.05).Antibody-positive rate was significantly higher in female recipients than in male recipients (P ＜ 0.01).Antibody-positive rate was significantly higher in recipients that received renal transplantation for the second time than in recipients that received renal transplantation for the first time (P ＜ 0.01).With HLA cross-reactive group mismatching increasing,survival rate of renal allograft presented a tendency of decline.One,three and five years after renal transplantation,the survival rate of renal allograft was respectively 97%,94%,and 92% for recipients with no mismatching,and 91%,82%,and 77% for recipients with two mismatches,which was respectively decreased by 6%,12%,and 15% compared to recipients that received no mismatching.For recipients with three mismatches,the survival rate of renal allograft was respectively decreased by 9%,15%,and 24% compared to recipients with no mismatching.

CONCLUSION:

C4d deposition on the capillary wall around the renal tubule can be detected as an indicator of antibody-mediated humoral rejection.A good HLA matching can noticeably decrease the incidence of rejection and improve the survival of renal allograft.