Protective anti-donor IgM production after crossmatch positive liver-kidney transplantation

Characteristics of Immunoglobulin M Type Antibodies of Different Origins from the Immunologic and Clinical Viewpoints and Their Application in Controlling Antibody-Mediated Allograft Rejection

Antibody-mediated allograft rejection (AMR) hinders patient prognosis after organ transplantation. Current studies concerning AMR have mainly focused on the diagnostic value of immunoglobulin G (IgG)-type donor-specific antihuman leukocyte antigen antibodies (DSAs), primarily because of their antigen specificity, whereas the clinical significance of immunoglobulin M (IgM)-type DSAs has not been thoroughly investigated in the context of organ transplantation because of their nonspecificity against antigens. Although consensus regarding the clinical significance and role of IgM antibodies is not clear, as discussed in this review, recent findings strongly suggest that they also have a huge potential in novel diagnostic as well as therapeutic application for the prevention of AMR. Most serum IgM antibodies are known to comprise natural antibodies with low affinity toward antigens, and this is derived from B-1 cells (innate B cells). However, some of the serum IgM-type antibodies reportedly also produced by B-2 cells (conventional B cells). The latter are known to have a high affinity for donor-specific antigens. In this review, we initially discuss how IgM-type antibodies of different origins participate in the pathology of various diseases, directly or through cell surface receptors, complement activation, or cytokine production. Then, we discuss the clinical applicability of B-1 and B-2 cell-derived IgM-type antibodies for controlling AMR with reference to the involvement of IgM antibodies in various pathological conditions.

Anti-Pituitary and Anti-Hypothalamus Autoantibody Associations with Inflammation and Persistent Hypogonadotropic Hypogonadism in Men with Traumatic Brain Injury

Traumatic brain injury (TBI) and can lead to persistent hypogonadotropic hypogonadism (PHH) and poor outcomes. We hypothesized that autoimmune and inflammatory mechanisms contribute to PHH pathogenesis. Men with moderate-to-severe TBI (n = 143) were compared with healthy men (n = 39). The TBI group provided blood samples 1-12 months post-injury (n = 1225). TBI and healthy control (n = 39) samples were assayed for testosterone (T) and luteinizing hormone (LH) to adjudicate PHH status. TBI samples 1-6 months post-injury and control samples were assayed for immunoglobulin M (IgM)/immunoglobulin G (IgG) anti-pituitary autoantibodies (APA) and anti-hypothalamus autoantibodies (AHA). Tissue antigen specificity for APA and AHA was confirmed via immunohistochemistry (IHC). IgM and IgG autoantibodies for glial fibrillary acid protein (GFAP) (AGA) were evaluated to gauge APA and AHA production as a generalized autoimmune response to TBI and to evaluate the specificity of APA and AHA to PHH status. An inflammatory marker panel was used to assess relationships to autoantibody profiles and PHH status. Fifty-one men with TBI (36%) had PHH. An age-related decline in T levels by both TBI and PHH status were observed. Injured men had higher APA IgM, APA IgG, AHA IgM, AHA IgG, AGA IgM, and AGA IgG than controls (p < 0.0001 all comparisons). However, only APA IgM (p = 0.03) and AHA IgM (p = 0.03) levels were lower in the PHH than in the non-PHH group in multivariate analysis. There were no differences in IgG levels by PHH status. Multiple inflammatory markers were positively correlated with IgM autoantibody production. PHH was associated with higher soluble tumor-necrosis-factor receptors I/II, (sTNFRI, sTNFRII), regulated on activation, normal T-cell expressed and secreted (RANTES) and soluble interleukin-2-receptor-alpha (sIL-2Rα) levels. Higher IgM APA, and AHA, but not AGA, in the absence of PHH may suggest a beneficial or reparative role for neuroendocrine tissue-specific IgM autoantibody production against PHH development post-TBI.

The impact of alloantibodies directed against the second donor on long-term outcomes of repeat liver transplantation

Background

Despite reports that associate donor specific antibody (DSA) with rejection after liver transplantation, grafts are still allocated according to blood group (ABO) but not human leukocyte antigen (HLA) compatibility, possibly due to the absence of an easily discernible clinical association between adverse recipient outcome and DSA. Re-transplantation provides a test environment where the presence of preformed DSA is prevalent and its effect on outcome should be apparent.

Methods

All patients undergoing a second liver transplantation with available pre-operative serum were included with the exception of ABO incompatible or multiple organ transplants. Banked sera were tested for anti-HLA antibodies with Luminex-based solid phase assays. Anti-HLA antibodies to the second donor (D2SA) were determined using antibodies specificity and HLA typing of 2nd liver donor.

Results

Preformed HLA antibodies directed to second liver transplantation (D2SA) were found in 31 (39%) of the 79 patients that were included in the study. Primary and re-transplantation characteristics were similar in both subgroups except first graft survival which was significantly shorter in recipients who are negative for D2SA. Mean survival of the second graft was similar in D2SA+ and D2SA- cohorts [8.55 (range, 0.01-24.74) vs. 7.56 (range, 0-23.53) years respectively, P=0.574]. Mean patient survival after 2nd liver transplantation was similar in D2SA+ and D2SA- cohorts [9.11 (range, 0.01-24.74) vs. 8.10 (range, 0-23.53) years respectively, P=0.504]. Subgroup univariate analysis demonstrated no detrimental effect of class, locus, or strength of D2SA on survival of the second liver transplant. In multivariate cox regression model, neither class I D2DSA (HR =1.101, P=0.92) nor class II D2SA (HR =1.74, P=0.359) were significant risks of graft failure.

Conclusions

Presence of D2SA was not found to be associated with inferior outcomes in this retrospective cohort study of liver re-transplantation suggesting that changes to the allocation system are not required.

Anti-donor immunoglobulin G subclass in liver transplantation

Immunoglobulin G (IgG) subclasses in human health and immunity have only be sporadically studied in the half century since their discovery. Different patterns of IgG subclass production are seen if the immune response is deviated towards type 1 versus type 2. The current state of our knowledge of IgG subclasses in liver transplantation is reviewed here. While several studies have been conducted in liver disease, only four relatively small studies have been undertaken in liver transplant recipients. Total IgG4 elevation in serum is related to sclerosing pancreatico-cholangiopathy that is sensitive to treatment with steroids. Conventional immunosuppressive regimes, especially with a combination of tacrolimus and sirolimus, reduce the production of all IgG subclasses after transplantation but it is not known if they deviate the immune response. Presence of anti-donor IgG3 before transplantation, or its expansion after transplantation, has been associated with rejection and liver graft loss. Anti-GSTT1 IgG4 production after transplantation is associated with de-novo immune hepatitis. Greater knowledge of anti-donor IgG subclass responses after transplantation will allow us tailor novel treatments for greater effect.

IFN-γ production by memory helper T cells is required for CD40-independent alloantibody responses

Cognate T-B cell interactions and CD40-CD154 costimulation are essential for productive humoral immunity against T-dependent Ags. We reported that memory CD4 T cells can deliver help to B cells and induce pathogenic IgG alloantibodies in the absence of CD40-CD154 interactions. To determine cytokine requirements for CD40-independent help, we used CD40(-/-) mice containing differentiated subsets of donor-reactive memory Th cells as heart allograft recipients. Th1 and Th17, but not Th2, memory CD4 T cells elicited high titers of anti-donor Ab. Abs induced by Th17 memory CD4 T cells had decreased reactivity against donor MHC class I molecules and inferior ability to cause complement deposition in heart allografts compared with Abs induced by Th1 cells, suggesting a requirement for IFN-γ during CD40-independent help. IFN-γ neutralization inhibited helper functions of memory CD4 T cells in both CD40(-/-) recipients and wild type recipients treated with anti-CD154 mAb. Our results suggest that IFN-γ secreted by pre-existing memory helper cells determines both isotype and specificity of donor-reactive alloantibodies and can thus affect allograft pathology. This information may be valuable for identifying transplant patients at risk for de novo development of pathogenic alloantibodies and for preventing alloantibody production in T cell-sensitized recipients.

Antibody-mediated rejection despite inhibition of terminal complement

Terminal complement blockade has been shown to decrease the incidence of early acute antibody-mediated rejection (eAMR) in the first month after positive cross-match kidney transplant recipients, yet some patients still develop eAMR. The current study investigated possible mechanisms of eAMR despite eculizumab treatment. Of the 26 patients treated with eculizumab, two developed clinical eAMR and another patient developed histologic signs of eAMR without graft dysfunction ('subclinical eAMR'). Twenty-three did not have histologic injury on early surveillance biopsies. All 26 patients had therapeutic levels of eculizumab and showed complete blockade of complement in hemolytic assays. High levels of donor-specific alloantibody (DSA) including total IgG, IgG3, and C1q+ DSA were present in patients with and without eAMR, and none correlated well with eAMR. In contrast, IgM DSA was present in only four patients after transplantation: the two patients with clinical eAMR, one patient with subclinical AMR, and one patient without eAMR (P = 0.006 correlation with eAMR). Both clinical eAMR episodes were easily treated with plasma exchange which removed IgM more completely and rapidly than IgG, resulting in normalization of function and histology. These data suggest a possible role of antidonor IgM DSA in the pathogenesis of eAMR in patients treated with terminal complement blockade (ClinicalTrials.gov Identifier: NCT00670774).

Impact of IgM and IgG3 anti-HLA alloantibodies in primary renal allograft recipients

BACKGROUND

With standard IgG donor-specific anti-HLA antibody (DSA) testing, it is unclear which immunoglobulin-G (IgG) DSA positive patients will fail. We looked further into the immune response by studying immunoglobulin-M (IgM) and IgG subclass 3 (IgG3) DSA to determine if these identify the IgG DSA patients at highest risk for allograft loss.

METHODS

In 189 consecutively transplanted primary renal allograft recipients, sera were collected sequentially pre- and posttransplant. Of the 189, 179 patients had sera available to retrospectively test for anti-HLA IgG, IgM, and IgG3 antibodies via LABScreen single-antigen bead assay and were included in the study. All patients had a negative crossmatch. Per patient, all DSA (IgM, IgG3, and IgG) refers to the same serologic specificity.

RESULTS

Overall, 100 (56%) patients developed an alloimmune response (IgM or IgG DSA positive, or both). Ninety-five patients developed IgM DSA and 47 patients developed IgG DSA. IgM DSA was detected in 42 of 47 patients with IgG DSA. IgM DSA alone did not increase the allograft loss risk, whereas IgG DSA did (P=0.002). Once IgG DSA appeared, IgM DSA persisted in 33 patients and an isotype switch to IgG3 positive DSA occurred in 25 patients. Patients with IgM persistent IgG3 positive DSA (n=19) were more likely to have allograft failure than those without (P=0.02).

CONCLUSION

This study shows the evolution of the humoral immune response from IgM to IgG DSA posttransplant. We found that development of IgM persistent IgG3 positive DSA identifies the most dangerous IgG DSA subpopulation.

Alloantibody and autoantibody monitoring predicts islet transplantation outcome in human type 1 diabetes

Long-term clinical outcome of islet transplantation is hampered by the rejection and recurrence of autoimmunity. Accurate monitoring may allow for early detection and treatment of these potentially compromising immune events. Islet transplant outcome was analyzed in 59 consecutive pancreatic islet recipients in whom baseline and de novo posttransplant autoantibodies (GAD antibody, insulinoma-associated protein 2 antigen, zinc transporter type 8 antigen) and donor-specific alloantibodies (DSA) were quantified. Thirty-nine recipients (66%) showed DSA or autoantibody increases (de novo expression or titer increase) after islet transplantation. Recipients who had a posttransplant antibody increase showed similar initial performance but significantly lower graft survival than patients without an increase (islet autoantibodies P < 0.001, DSA P < 0.001). Posttransplant DSA or autoantibody increases were associated with HLA-DR mismatches (P = 0.008), induction with antithymocyte globulin (P = 0.0001), and pretransplant panel reactive alloantibody >15% in either class I or class II (P = 0.024) as independent risk factors and with rapamycin as protective (P = 0.006) against antibody increases. DSA or autoantibody increases after islet transplantation are important prognostic markers, and their identification could potentially lead to improved islet cell transplant outcomes.

Blood group O recipients associated with early graft deterioration in living ABO-incompatible kidney transplantation

BACKGROUND

Blood group O individuals are known to have larger amounts of anti-ABO blood group (anti-A/B) IgG antibodies than A or B individuals. Therefore, in ABO-incompatible (ABOI) kidney transplantation (KTX), it is expected that blood group O recipients are more likely to suffer graft damage, because anti-A/B IgG antibodies are believed to be responsible for worse graft outcomes.

METHODS

This study assessed the graft outcomes between blood group O and non-O recipients in ABOI-KTX. A total of 164 consecutive recipients who underwent ABOI-KTX between 1990 and 2007 under three different immunosuppressive protocols were enrolled in this study. The study population was divided into two groups: (i) recipients with blood group O (n=87) and (ii) recipients with blood group A or B (non-O) (n=77).

RESULTS

High anti-A/B IgG titers were predominant in the O group (P<0.001), whereas no significant difference was observed in the IgM titers. The overall graft survival rate did not differ between the two groups; however, the 6-month graft survival rate was significantly lower in the O group (86% vs. 97%, P=0.011). Among 14 recipients who suffered graft loss within 6 months after transplantation, 12 (86%) were O recipients. The cumulative incidence of acute antibody-mediated rejection was significantly higher in the O group (60 days, 31 vs. 14%, P=0.013).

CONCLUSION

Our results may indicate that being a blood group O recipient is at great risk for experiencing early allograft deterioration, probably caused by anti-A/B IgG antibodies in ABOI-KTX.

ABO-incompatible liver transplantation: a pathological analysis of 2 cases

AIM: To observe the pathological features of ABO-incompatible liver transplantation, and to investigate the diagnostic criteria for humoral rejection of liver transplantation.

METHODS: The pathological changes and the deposition of all kinds of immunoglobulins and complements were observed in 2 cases of ABO-incompatible liver transplantation by immunohistochemical and HE staining.

RESULTS: Under light microscope, hepatocyte edema, spotty necrosis, infiltration of lymphacytes and mononuclear cells in portal region were observed in the transplanted livers of both cases. Immunohistochemistry showed mixture of CD3- and CD20-positive cells and different degrees of linear or granular depositions of IgG, IgM, IgA, C4c, C4d and C1q in the liver sinusoidal endothelial cells. One of the cases was diagnosed with light acute cellular rejection accompanied by light humoral rejection, and the other was diagnosed with light liver preservation and reperfusion injury accompanied by light humoral rejection.

CONCLUSION: It may be regard as the evidence of humoral rejection in hepatic tissues that immunoglobulin G accompanied with C4d and other complements diffusely deposits in hepatic sinusoidal endothelial cells.

Management of Anti-allogeneic Antibody Elimination by Apheresis in Living Donor Liver Transplantation

In this study, we report on the indications and efficacy of the elimination of antiallogeneic antibodies in living donor liver transplant recipients. Seven patients incompatible with the ABO-blood type were subjected to apheresis before transplantation. The procedure resulted in titers being decreased to less than a score of 8. After transplantation, apheresis was also performed in 6 cases and continuous hemodiafiltration in 1 case. In addition, three out of 11 ABO-blood type incompatible recipients were administered anti-CD20 antibody (rituximab). Two crossmatch positive patients were subjected to apheresis before transplantation, and in these cases the titers were reduced to less than a score of 2. Moreover, these two patients had no acute rejections after transplantation. We concluded that apheresis is effective for preventing acute rejection induced by pre-existing anti-A and/or anti-B antibodies, as well as antidonor specific antibodies, but is not effective in some patients who had accelerated humoral rejection.

Combined Liver-Kidney Transplantation With Preformed Anti-HLA Antibodies: A Case Report

A pretransplant positive cross-match is a contraindication for kidney transplantation, unlike in liver transplantation (OLT). In combined liver kidney transplantation (LKT) it is hypothesized that liver can protect kidney from rejection. We report the case of a 35-year-old woman on renal replacement therapy with gastrointestinal tract compression due to a hematoma following spontaneous liver rupture (May 2004). She was affected by amyloidosis, treated with a bone marrow autotransplantation (2001). The liver rupture was surgically untreatable, so an LKT was proposed. Panel-reactive antibody was 80% to 100% (complement dependent cytotoxicity) with specific anti-HLA antibodies (enzyme-linked immunosorbent assay). A compatible donor was found (July 2004). The cross-match before LKT was positive for B and T cells (score 8): an emergency OLT was performed. Immediately after liver reperfusion the cross-match result was less positive (6) for T cells. After 6 hours it was negative for T and slightly positive for B cells (4): the kidney was transplanted. The immunosuppressive therapy was: alemtuzumab, steroids, and tacrolimus. Renal function immediately recovered. On day 7 a rejection episode was successfully treated by increasing steroids (intravenous bolus). At discharge hepatic and renal function were normal (creatinine 1 mg/dL). They are stable after 1 year. This case showed LKT efficacy even in complex immunological situations. Many immunological mechanisms, still not defined, are hypothesized about the protective role of the liver. This case confirmed experimental data that highlighted that in vivo in humans a cross-match can change from positive to negative after OLT giving highly sensitized patients the possibility for LKT.

Immunoglobulin-G subclass antidonor reactivity in transplant recipients

Outcomes may differ after kidney transplantation compared to combined liver-kidney transplantation. In animal models, distinct patterns of antidonor immunoglobulin (Ig) G subclasses are associated with either rejection or transplant tolerance. Flow cytometry has increased the sensitivity of antidonor immunoglobulin detection. We compared antidonor IgG subclass responses in kidney transplant recipients to those in recipients of liver or multiorgan grafts. In this study of 19 organ (kidney, liver, pancreas) transplantations, recipient serum incubated with donor splenocytes was tested by flow cytometry for the presence of IgM, IgG, or IgG subclass 1-4. Sera before transplantation and 10 days and 100 days after transplantation were used. No differences were seen in antidonor IgM, IgG, or IgG subclass antibodies among recipients of kidney transplants and liver grafts or combination grafts, either before or after transplantation. IgG4 gradually but significantly increased after transplantation in all groups. High levels of antidonor IgG3 either before transplantation or produced after it were found in 3 kidney recipients who experienced acute rejection. No other patients experienced rejection, and no other increase in IgG3 was seen. In conclusion, antidonor IgG subclass profiles may be useful to distinguish populations at risk of rejection but they do not differentiate the immunological response after kidney transplantation from that after liver or combined transplantation. A late rise in antidonor IgG4 is consistent with decreased antidonor reactivity thought to occur late after transplantation.