Development of donor-specific microchimerism in liver transplant recipient with HLA-DRB1 and -DQB1 mismatch related to rejection episodes

A fast and simple method for detecting and quantifying donor-derived cell-free DNA in sera of solid organ transplant recipients as a biomarker for graft function

Timely detection of graft rejection is an important issue in the follow-up care after solid organ transplantation. Until now, biopsy has been considered the “gold standard” in the diagnosis of graft rejection. However, non-invasive tests such as monitoring the levels of cell-free DNA (cfDNA) as a sensitive biomarker for graft integrity have attracted increasing interest. The rationale of this approach is that a rejected organ will lead to a significant release of donor-derived cfDNA, which can be detected in the serum of the transplant recipient.

We have developed a novel quantitative real-time PCR (qPCR) approach for detecting an increase of donor-derived cfDNA in the recipient’s serum. Common insertion/deletion (InDel) genetic polymorphisms, which differ between donor and recipient, are targeted in our qPCR assay. In contrast to some other strategies, no specific donor/recipient constellations such as certain gender combinations or human leukocyte antigen (HLA) discrepancies are required for the application of our test.

The method was first validated with serial dilutions of serum mixtures obtained from healthy blood donors and then used to determine donor-derived cfDNA levels in patients’ sera within the first 3 days after their kidney transplantation had been performed.

Our method represents a universally applicable, simple and cost-effective tool which can potentially be used to detect graft dysfunction in transplant recipients.

Ingraft chimerism in lung transplantation--a study in a porcine model of obliterative bronchiolitis

Background

Bronchial epithelium is a target of the alloimmune response in lung transplantation, and intact epithelium may protect allografts from rejection and obliterative bronchiolitis (OB). Herein we study the influence of chimerism on bronchial epithelium and OB development in pigs.

Methods

A total of 54 immunosuppressed and unimmunosuppressed bronchial allografts were serially obtained 2-90 days after transplantation. Histology (H&E) was assessed and the fluorescence in situ hybridization (FISH) method for Y chromosomes using pig-specific DNA-label was used to detect recipient derived cells in graft epithelium and bronchial wall, and donor cell migration to recipient organs. Ingraft chimerism was studied by using male recipients with female donors, whereas donor cell migration to recipient organs was studied using female recipients with male donors.

Results

Early appearance of recipient-derived cells in the airway epithelium appeared predictive of epithelial destruction (R = 0.610 - 0.671 and p < 0.05) and of obliteration of the bronchial lumen (R = 0.698 and p < 0.01). All allografts with preserved epithelium showed epithelial chimerism throughout the follow-up. Antirejection medication did not prevent, but delayed the appearance of Y chromosome positive cells in the epithelium (p < 0.05), or bronchial wall (p < 0.05).

Conclusions

In this study we demonstrate that early appearance of Y chromosomes in the airway epithelium predicts features characteristic of OB. Chimerism occurred in all allografts, including those without features of OB. Therefore we suggest that ingraft chimerism may be a mechanism involved in the repair of alloimmune-mediated tissue injury after transplantation.

Prospective analysis between the therapy of immunosuppressive medication and allogeneic microchimerism after liver transplantation

After liver transplantation, migration of donor-derived hematopoietic cells to recipient can be detected in peripheral blood. This state is termed microchimerism. The aim of this study was to investigate prospectively the presence of allogeneic microchimerism, the occurrence of acute cellular rejection and the level of immunosuppression in transplanted patients. Microchimerism occurrence between 10 days and 12 months after liver transplantation was analyzed in 47 patients aged between 15 and 65 by a two-stage nested PCR/SSP technique to detect donor MHC HLA-DR gene specifically. A pre-transplant blood sample was collected from each patient to serve as individual negative control. Microchimerism was demonstrated in 32 (68%) of the 47 patients; of these, only 10 patients (31.2%) presented rejection. Early microchimerism was observed in 25 patients (78.12%) and late microchimerism in 7 patients (21.8%). Among the patients with microchimerism, 14 were given CyA and 18 were given FK506. In the group without microchimerism, 12 patients were given CyA and 03 were given FK506. There was a significant association between the presence of microchimerism and the absence of rejection (p=0.02) and also between microchimerism and the type of immunosuppression used. Our data indicate that microchimerism and probably differentiation of donor-derived leukocytes can have relevant immunologic effects both in terms of sensitization of recipient and in terms of immunomodulation toward tolerance induction.

Combined HLA-DR and -DQ disparity is associated with a stable course of ulcerative colitis after liver transplantation for primary sclerosing cholangitis

Combined disparity of human leukocyte antigen (HLA)-DR and -DQ between mother and fetus is associated with less severe ulcerative colitis (UC) during pregnancy. We evaluated whether donor-recipient HLA disparity after liver transplantation (LT) affects UC in patients with primary sclerosing cholangitis (PSC). Sixty-nine consecutive patients with PSC underwent LT; all underwent colonoscopy before LT; 48 had UC before and 3 had de novo UC after LT. Clinical and laboratory data, activity and treatment of UC, post-LT cytomegalovirus infection, and disparity of HLA-A, -B, -DR, and -DQ for each donor-recipient pair were evaluated. Pre-LT quiescent UC was present in 26 patients. Post-LT UC activity was evaluated in 36 of 51 patients with UC who had not undergone pre-LT colectomy and who had >12 months' post-LT survival. Of these, 16 were stable, 17 had worsened, and 3 had de novo UC. Seven required colectomy (4 for dysplasia or cancer) after LT. Post-LT cytomegalovirus viremia was neither associated with worse UC activity (P = 0.58) nor de novo UC. Disparity with respect to HLA-A, -B, -DR, and -DQ was found in 58%, 27%, 44%, and 39% donor-recipient pairs, respectively. Post-LT UC course was similar with respect to single HLA disparity. However, disparity in none or only one HLA-DR or -DQ was significantly associated with worse activity compared with patients with disparity at both (65% vs. 0%, P = 0.009). Logistic regression found that the disparity for both -DR and -DQ was the only factor statistically significantly associated with post-LT UC activity. We conclude that disparity in both HLA-DR and -DQ between donor and recipient is associated with stable UC activity after LT.

Presence of donor-and-recipient-derived DNA microchimerism in the cell-free blood samples of renal transplantation recipients associates with the acceptance of transplanted kidneys

AIM

To examine whether the existence of the donor-and recipient-derived DNA chimerism in recipient's plasma can be a predictive marker for the status of transplanted organ.

METHODS

One hundred and twenty-six female patients who had been transplanted with male kidneys were enrolled in the present study. In these female recipients, the SRY(1), DYZ(1)(1st) and DYZ(1)(2nd) genes on the Y chromosome from the plasma were prospectively examined using reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

SRY, DYZ(1)(1st) and DYZ(1)(2nd) sequences were detected in the cell-free blood (plasma) of 97 (77%) of 126 female patients with male kidney. The average time that the transplanted kidneys functioned was 8.7 years and 5.4 years among microchimerism-positive and microchimerism-negative recipients, respectively. The frequency of the patients who had acute rejection after renal transplantation was approximately 10% and 28% in microchimerism-positive and microchimerism-negative recipients, respectively. Serum creatinine levels in microchimerism-positive patients were significantly lower than those in microchimerism-negative patients.

CONCLUSION

These results suggest that plasma DNA microchimerism present in certain patients following renal transplantation and measurement of plasma DNA microchimerism using quantitative RT-PCR might be a useful predictor for the acceptance of transplanted kidneys.

Frequency of Recipient-Derived Chimerism and Relationship With Acute Rejection and HLA Tissue Typing in Transplanted Livers

BACKGROUND

We sought to determine the extent and time course of recipient-derived chimerism after transplantation and the relationship with acute rejection episodes (ARE) and HLA typing in hepatic allograft patients.

PATIENTS AND METHODS

We studied 18 needle liver biopsy specimens from patients who had undergone orthotopic liver transplantation. Fluorescent in situ hybridization (FISH) analysis for X and Y chromosomes was performed in all cases with a sex mismatch. To evaluate the HLA matching, we used serological and polymerase chain reaction (PCR) methodology.

RESULTS

There was a sex mismatch between the recipients and donors in all cases. X and Y chromosome chimerism was detected in 14 of 18 (83%; 31.14 +/- 27.4) patients. Also, no statistical association was found between the presence and the extent of chimerism and clinicopathological parameters (P < .05).

CONCLUSIONS

Our results suggest that chimerism was frequently seen in liver allografts, but it did not influence the occurrence of ARE, tissue compatibility, or histopathological changes in the posttransplantation period. The clinical, immunological, and histopathological relevance of chimerism remain unclear. These results may relate to the small number of patients and disproportion of chimerism-positive versus-negative cases. Further prospective studies will be required to clarify these findings in a larger population of liver transplant patients.

Neutrophils and lymphoid chimerism after adult living-related liver transplantation from a homozygous donor

Chimerism and graft-versus-host disease (GVHD) pose significant risks to liver transplant patients. The risk of chimerism and GVHD is higher among cases of living-related liver transplant (LRLT). Donors homozygous at all HLA loci carry a higher risk for GVHD. Herein we present a case of LRLT. The recipient suffered from end-stage liver disease and received a right lobe graft from his son. After 8 months posttransplant, the patient developed profound bone marrow depression. The patient was negative for CMV, Brucella, HHV6, HHV8, HBV, HCV, and parvovirus. No skin or GI signs of GVHD were noted. The patient and donor were HLA typed by SSP. The donor was homozygous for all HLA loci while the patient shared the class II homozygosity and was class I heterozygous. Chimerism studies were prompted after noting that the neutrophil compartment of the patient was homozygous for all HLA loci. This initiated further studies of the PMN and lymphocytes by microsatellite analysis. A total 15 microsatellites were analyzed. The results suggest that the majority (75%) of the PMNs and 45% of the lymphocytes were of donor origin. The patient was treated with G-CSF; his WBC counts returned to normal. At 2.5 years posttransplant the patient had not developed GVHD, despite the large number of donor lymphocytes circulating in his bloodstream. The only complaint he had was severe arthritis, which was treated with steroids. It must be investigated whether this was the result of GVHD.