A randomized and prospective study comparing treatment with high-dose intravenous immunoglobulin with monoclonal antibodies for rescue of kidney grafts with steroid-resistant rejection

Hypogammaglobulinemia and infection risk in solid organ transplant recipients

PURPOSE OF REVIEW

Hypogammaglobulinemia may develop as a result of a number of immune deficiency syndromes that can be devastating. This review article explores the risk of infection associated with hypogammaglobulinemia in solid organ transplantation and discusses therapeutic strategies to alleviate such a risk.

RECENT FINDINGS

Hypogammaglobulinemia is associated with increased risk of opportunistic infections, particularly during the 6-month posttransplant period when viral infections are most prevalent. The preemptive use of immunoglobulin replacement results in a significant reduction of opportunistic infections in patients with moderate and severe hypogammaglobulinemia.

SUMMARY

Monitoring immunoglobulin G levels may aid in clinical management of solid organ transplant recipients. The preemptive use of immunoglobulin replacement may serve as a new strategy for managing solid organ transplant recipients with hypogammaglobulinemia.

Mechanisms of corneal allograft rejection and regional immunosuppression

Corneal transplantation has not matched the improvements in outcome seen with other clinical transplantation procedures. The therapeutic strategies, which have improved the outcomes of solid vascularised organs are not applicable to corneal transplantation. Corneal transplantation is different with respect to relevant transplantation biology and the clinical context in which it is practiced. New approaches need to be developed which provide regional rather than systemic immunosuppression. The accessibility of the cornea makes it particularly suitable for topical medication and for gene therapy approaches. Engineered antibodies, small enough to pass through the cornea, and directed at key molecules in the allograft response have been developed. Gene therapy had been developed using viral vectors to transfect the corneal endothelium with the genes for immunosuppressive lymphokines. Both approaches show promise.

Intravenous immunoglobulin as rescue therapy for BK virus nephropathy

BKVN has emerged as an important cause of pediatric renal allograft nephropathy, with significant graft dysfunction in majority of the cases. Reduced immunosuppression and cidofovir therapy are the most commonly used therapeutic options for the treatment of BKVN in these patients. Recently, a preliminary study in adult renal allograft recipients with BKVN showed a therapeutic response to a combined approach of immunosuppression reduction and IVIg administration. A therapeutic benefit of IVIg without another concomitant treatment intervention has not been evaluated. We report stabilization of renal functions, histological resolution of BKVN and significant reduction in BK viremia in pediatric renal transplant with the use of IVIg, after an inadequate response to immunosuppression reduction and cidofovir therapy. In addition, we review the current literature on the use of cidofovir in pediatric renal transplant patients with BKVN and the potential of IVIg use in this condition.

Modulation of the cellular immune system by intravenous immunoglobulin

Intravenous immunoglobulin (IVIg) is therapeutically used in a variety of immune-mediated diseases. The beneficial effects of IVIg in auto-antibody-mediated diseases can be explained by neutralization, accelerated clearance and prevention of Fcgamma-receptor binding of auto-antibodies. However, the means by which IVIg exerts therapeutic effects in disorders mediated by cellular immunity have remained enigmatic. Clinical improvements, followed by IVIg treatment, often extend beyond the half-life of infused IgG, thereby indicating that IVIg modifies the cellular immune compartment for a prolonged period. Here, we discuss recent advances in the understanding of different, mutually non-exclusive mechanisms of action of IVIg on cells of the innate and adaptive immune system. These mechanisms might explain the beneficial effects of IVIg in certain autoimmune and inflammatory diseases.

Posttransplant prophylactic intravenous immunoglobulin in kidney transplant patients at high immunological risk: a pilot study

The effects of posttransplant prophylactic intravenous immunoglobulin (IVIg) were investigated in renal transplant recipients at high immunological risk. Thirty-eight deceased-donor kidney transplant recipients with previous positive complement-dependent cytotoxicity crossmatch (n=30), and/or donor-specific anti-HLA antibodies (n=14) were recruited. IVIg (2 g/kg) was administrated on days 0, 21, 42 and 63 with quadruple immunosuppression. Biopsy-proven acute cellular and humoral rejection rates at month 12 were 18% and 10%, respectively. Glomerulitis was observed in 31% and 60% of patients at months 3 and 12, respectively, while allograft glomerulopathy rose from 3% at month 3 to 28% at 12 months. Interstitial fibrosis/tubular atrophy increased from 18% at day 0 to 51% and 72% at months 3 and 12 (p<0.0001). GFR was 50 +/- 17 mL/min/1.73 m(2) and 48 +/- 17 mL/min/1.73 m(2) at 3 and 12 months. PRA decreased significantly after IVIg (class I: from 18 +/- 27% to 5 +/- 12%, p<0.01; class II: from 25 +/- 30% to 7 +/- 16%, p<0.001). Patient and graft survival were 97% and 95%, respectively and no graft was lost due to rejection (mean follow-up 25 months). In conclusion, prophylactic IVIg in high-immunological risk patients is associated with good one-year outcomes, with adequate GFR and a profound decrease in PRA level, but a significant increase in allograft nephropathy.

Pretransplant immunomodulation of highly sensitized small bowel transplant candidates with intravenous immune globulin

Presence of preformed lymphocytotoxic antibodies may represent a barrier to isolated intestinal transplantation (IITx). We developed an intravenous immunoglobulins (IVIg) based desensitization protocol for candidates with high panel-reactive antibodies (PRA). Six patients with a mean PRA of 72+/-22% were included in a four-level (L) protocol with escalating doses of IVIg (L1, L2), addition of mycophenolate mofetil (MMF) or plasmapheresis (L3); and anti-CD20 (Rituximab) (L4). Four of six candidates improved their PRAs (from a mean of 66.2% to 25.5%; P=0.01) and were successfully transplanted. At a mean follow-up of 8 months, number and severity of rejection episodes of protocol patients did not differ from patients with low PRA transplanted during the same period. These data support the use of IVIg to desensitize patients waiting for IITx. It increases the applicability of IITx, and reduces the waiting time and mortality on the waiting list with outcomes comparable to nonsensitized recipients.

Pharmacotherapeutic options for the management of human polyomaviruses

Polyomaviruses [BK virus (BKV), JC virus (JCV) and simian virus 40 (SV40)] have been known to be associated with diseases in humans for over thirty years. BKV-associated nephropathy and JCV-induced progressive multifocal leukoencephalopathy (PML) were for many years rare diseases occurring only in patients with underlying severe impaired immunity. Over the past decade, the use of more potent immunosuppression (IS) in transplantation, and the Acquired Immune Deficiency Syndrome (AIDS) epidemic, have coincided with a significant increase in the prevalence of these viral complications. Prophylactic and therapeutic interventions for human polyomavirus diseases are limited by our current understanding of polyomaviral pathogenesis. Clinical trials are limited by small numbers of patients affected with clinically significant diseases, lack of defined risk factors and disease definitions, no proven effective treatment and the overall significant morbidity and mortality associated with these diseases. This chapter will focus on a review of the current and future research related to therapeutic targets and interventions for polyomavirus-associated diseases.

Superior Immunomodulatory Effects of Intravenous Immunoglobulins on Human T-cells and Dendritic Cells: Comparison to Calcineurin Inhibitors

BACKGROUND

Prophylactic administration of anti-HBs intravenous immunoglobulins (IVIg) in hepatitis B infected-liver transplant patients protects against acute rejection. To explore the suitability of intravenous immunoglobulins (IVIg) as prophylaxis of acute rejection and graft-versus-host disease (GVHD) after allograft transplantation, the effects of IVIg and calcineurin inhibitors (CNI) on human blood-derived T-cells and DC were compared.

METHODS

T-cells were stimulated with phytohemagglutinin (PHA) or allogeneic spleen antigen-presenting cells (APC) and T-cell proliferation and cytokine production were determined in presence or absence of IVIg or CNI. Immature blood dendritic cells (DC) were stimulated in presence or absence of IVIg or CNI, and allogeneic T-cell stimulatory capacity, cell death, and phenotypic maturation were established.

RESULTS

IVIg and CNI equally inhibited T-cell proliferation and IFN-gamma production after PHA stimulation or allogeneic stimulation. CD8+ T-cells were preferentially affected by both IVIg and CNI after allogeneic stimulation. Like CNI, addition of IVIg at later time points after T-cell activation suppressed mitotic progression of responding T-cells. IVIg-treated DC were suppressed in their capacity to stimulate allogeneic T-cell proliferation by 73+/-12%, whereas DC-function was not affected by CNI. The decreased allogeneic T-cell stimulatory capacity of IVIg-treated DC correlated to induction of cell death in DC and decreased up-regulation of CD40 and CD80.

CONCLUSIONS

In vitro IVIg functionally inhibit the two principal immune cell-types involved in rejection and GVHD, i.e. T-cells and DC, whereas CNI only suppress T-cells. By targeting both T-cells and DC, IVIg may be a promising candidate for immunosuppressive treatment after allograft transplantation.

Current usage of intravenous immune globulin and the rationale behind it: the Massachusetts General Hospital data and a review of the literature

BACKGROUND

Intravenous immune globulin (IVIG) has been approved by the Food and Drug Administration (FDA) for use in 6 conditions: immune thrombocytopenic purpura (ITP), primary immunodeficiency, secondary immunodeficiency, pediatric HIV infection, Kawasaki disease, prevention of graft versus host disease (GVHD) and infection in bone marrow transplant recipients. However, most usage is for off-label indications, and for some of these comprehensive guidelines have been published.

STUDY DESIGN AND METHODS

We retrospectively reviewed all approved IVIG transfusions at Massachusetts General Hospital in 2004 to identify the current usage pattern and completed a literature review.

RESULTS

IVIG was most commonly used in the treatment of chronic neuropathy, which included chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy. For such patients, the annual cost of IVIG can exceed 50,000 dollars per patient. Other common indications were the treatment of hypogammaglobulinemia, ITP, renal transplant rejection, myasthenia gravis, Guillain-Barre syndrome, necrotizing fasciitis, autoimmune hemolytic anemia, and Kawasaki disease. IVIG was administered in a variety of other indications each representing <3% of the total treated patients.

CONCLUSION

Only a few indications account for most of the usage for IVIG. Reports concerning IVIG continue to grow at a tremendous pace but few high-quality randomized controlled trials have been reported. Randomized trials are especially needed for conditions such as CIDP, which consume large quantities of product.

Polyclonal and monoclonal antibodies for treating acute rejection episodes in kidney transplant recipients

BACKGROUND

Registry data shows that between 15-35% kidney recipients will undergo treatment for at least one episode of acute rejection within the first post transplant year. Treatment options include pulsed steroid therapy, the use of an antibody preparation, the alteration of background immunosuppression, or combinations of these options. In 2002, in the US, 61.4% patients with an acute rejection episode received steroids, 20.4% received an antibody preparation and 18.2% received both.

OBJECTIVES

To determine the benefits and harms of mono- or polyclonal antibodies (Ab) used to treat acute rejection in kidney transplant recipients.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (in The Cochrane Library, issue 2, 2005), MEDLINE (1966-June 2005), EMBASE (1980-June 2005), and the specialised register of the Cochrane Renal Group (June 2005).

SELECTION CRITERIA

Randomised controlled trials (RCTs) in all languages comparing all mono- and polyclonal antibody preparations, given in combination with any other immunosuppressive agents, for the treatment of acute graft rejection, when compared to any other treatment for acute rejection.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trials for eligibility and quality, and extracted data. Results are expressed as relative risk (RR) with 95% confidence intervals (CI).

MAIN RESULTS

Twenty one trials (49 reports, 1387 patients) were identified. Trials were generally small, incompletely reported, especially for potential harms, and did not define outcome measures adequately. Fourteen trials (965 patients) compared therapies for first rejection episodes. Ab was better than steroid in reversing rejection (RR 0.57, 95% CI 0.38 to 0.87) and preventing graft loss (death censored RR 0.74, CI 0.58 to 0.95) but there was no difference in preventing subsequent rejection or death at one year. Seven trials (422 patients) investigated Ab treatment of steroid-resistant rejection. There was no benefit of muromonab-CD3 over ATG or ALG in either reversing rejection, preventing subsequent rejection, preventing graft loss or death.

AUTHORS' CONCLUSIONS

In reversing first rejection, any antibody is better than steroid and also prevents graft loss, but subsequent rejection and patient survival are not significantly different. In reversing steroid-resistant rejection the effects of different antibodies are also not significantly different. Given the clinical problem caused by acute rejection, data are very sparse, and clinically important differences in outcomes between widely used interventions have not been excluded. Standardised reproducible outcome criteria are needed.

Presensitization: the problem and its management

Much attention has been placed recently on transplantation in highly HLA-sensitized patients. In attempts to remove these antibodies and enable successful transplantation, several novel approaches have been developed. These include intravenous Ig (IVIg), mycophenolate mofetil, sirolimus, alemtuzumab, protein A immunoabsorption, and rituximab. IVIg has emerged as a very effective agent when used alone in high dose or when used in low dose and combined with plasmapheresis. Although alemtuzumab has been used to eliminated B cells, it fails to prevent antibody-mediated rejection and therefore probably is not suitable for desensitization. Rituximab, a B cell-specific antibody, seems to be safe and to have some efficacy as a sole agent in elimination of alloantibodies but most likely will require combination therapy with IVIg or other agents. Newer agents, such as humanized anti-CD20, are being developed. Despite the great interest in the problem of allosensitization, with one notable exception, there is a major deficiency in controlled clinical trials, the conduct of which should be a focus for the near future.

Miliary tuberculosis in a Caucasian male transplant recipient and the role of intravenous immunoglobulin as an immunosuppressive sparing agent (Case Report)

Opportunistic infections are a common and anticipated accompaniment of transplantation, but are generally somewhat predictable in their timing and epidemiology. The authors report here a case of miliary tuberculosis occurring within 3 weeks of transplantation, in a patient not expected to be significantly at risk, and with a normal chest X-ray at the time of transplantation. A 25-year-old Caucasian male dialysis patient who received two paediatric kidneys as an en bloc renal transplant developed fever 3 weeks following transplantation; this eventually proved to be miliary tuberculosis. As well as antituberculous therapy and a significant reduction in the patient's conventional immunosuppression, intravenous immunoglobulin was used as anti-rejection prophylaxis. The case highlights the immunosuppressed status of dialysis patients prior to transplantation and the need for broad differential diagnosis in transplant recipients even in the absence of recognized epidemiological factors. The case also emphasizes the role of intravenous immunoglobulin as an anti-rejection therapy that does not add to the patient's immunosuppressive burden.

Intravenous gammaglobulin (IVIG): a novel approach to improve transplant rates and outcomes in highly HLA-sensitized patients

Intravenous immunoglobulin (IVIG) products are derived from pooled human plasma and have been used for the treatment of primary immunodeficiency disorders for more than 24 years. Shortly after their introduction, IVIG products were also found to be effective in the treatment of autoimmune and inflammatory disorders. Over the past 2 decades, the list of diseases where IVIG has a demonstrable beneficial effect has grown rapidly. These include Kawasaki disease, Guillain-Barre syndrome, myasthenia gravis, dermatomyositis and demyelinating polyneuropathy. Recently, we have described a beneficial effect on the reduction of anti-HLA antibodies with subsequent improvement in transplantation of highly HLA-sensitized patients as well as a potent anti-inflammatory effect that is beneficial in the treatment of antibody-mediated rejection (AMR). These advancements have enabled transplantation of patients previously considered untransplantable. These studies and relevant mechanism(s) of action will be discussed here.

Immunosuppressive agents in solid organ transplantation: Mechanisms of action and therapeutic efficacy

Effective immunosuppression is an essential pre-requisite for successful organ transplantation and improvements in outcome after transplantation have to a large extent been dependent on developments in immunosuppressive therapy. Here we provide an overview of the different immunosuppressive agents currently used in solid organ transplantation. A historical perspective on the development of immunosuppression for organ transplantation is followed by a review of the individual agents, with a focus on their mechanism of action and efficacy. Steroids, anti-proliferative agents (azathioprine and mycophenolate), calcineurin inhibitors (cyclosporine and tacrolimus) and TOR inhibitors (sirolimus and everolimus) are discussed along with both polyclonal and monoclonal antibody preparations. Many of the key clinical trials that underpin current clinical usage of these agents are described and side-effects of the different agents are highlighted. Finally, a number of newer agents still in various stages of clinical development are briefly considered.

High dose intravenous immunoglobulin treatment: mechanisms of action

Intravenous immunoglobulin (IVIg) treatment was introduced as replacement therapy for patients with antibody deficiencies, but evidence suggests that a wide range of immune-mediated conditions could benefit from IVIg. The immunoglobulins are precipitated from human plasma by fractionation methods. In conclusion, the differences in basic fractionation methods and the addition of various modifications for purification, stabilization, and virus inactivation result in products significantly different from each other.

Overcoming Immunologic Incompatibility: Transplanting the Difficult to Transplant Patient

Immunologic incompatibilities between donor and recipient have limited the access to renal transplantation for many patients. Previously the presence of donor-specific alloantibodies directed against donor major histocompatibility complex (MHC) antigens or natural antibodies directed against donor ABO blood group antigens was considered an absolute contraindication to renal transplantation. However, with the current understanding of humoral immune responses, superior immunosuppressive agents, and improved diagnosis and treatment of antibody-mediated rejection, renal transplantation can be safely performed with outstanding results despite the presence of donor-specific antibody. In this review we discuss the biology of antibody-mediated rejection and sensitization. We discuss the diagnostic tests necessary to characterize the type, affinity, and avidity of the donor-directed antibodies. Current methods for performing renal transplants across ABO and human leukocyte antigen (HLA)-sensitized barriers are covered, including the potential morbidities. The rest of the review focuses on advances in managing these antibodies to increase the likelihood of receiving a deceased donor kidney or allow transplantation from a living donor against whom one has a prohibitive antibody.

Hepatitis B immunoglobulins inhibit dendritic cells and T cells and protect against acute rejection after liver transplantation

The efficacy of anti-viral intravenous immunogobulins (anti-HBs Ig and anti-CMV Ig) in preventing acute rejection after liver transplantation was assessed in a retrospective analysis, and correlated to their effects on immune cells in vitro. HBs Ag-positive liver graft recipients (n = 40) treated prophylactically with anti-HBs Ig had a significantly lower incidence of acute rejection compared with recipients without viral hepatitis (n = 147) (12% vs. 34%; p = 0.012), while the incidence of rejection in HCV-positive recipients (n = 29) was similar to that in the control group. Treatment with anti-CMV Ig (n = 18) did not protect against rejection. In vitro, anti-HBs Ig suppressed functional maturation of and cytokine production by human blood-derived dendritic cells (DC) at concentrations similar to the serum concentrations reached during anti-HBs Ig treatment of liver graft recipients. In addition, anti-HBs Ig inhibited allo-antigen- and lectin-stimulated proliferation of peripheral T cells. Anti-CMV Ig suppressed functional DC-maturation and alloantigen-stimulated T-cell proliferation, but not lectin-driven T-cell proliferation. In conclusion, anti-HBs Ig protects against acute rejection after liver transplantation, probably by functional inhibition of the two principal immune cells involved in allograft rejection, DC and T cells.

Current approaches to treatment of antibody-mediated rejection

Antibody-mediated rejection (AMR) has recently been recognized as a significant and unique form of rejection that is not amenable to treatment with standard immunosuppressive medications aimed at modification of T-cell function. Recent interest in AMR and the role of B cells in rejection has been aided by the concomitant discovery that C4d staining of renal biopsy tissue is strongly associated with AMR and a poor prognosis, and the emergence of desensitization protocols for treatment of highly human leukocyte antigen (HLA)-sensitized patients. Treatment options include: (i) the use of high-dose intravenous immunoglobulin (IVIG) which works by blocking anti-HLA antibody activity and through complement inhibition, (ii) the use of Rituxan (anti-CD20 chimeric antibody) to deplete B cells and interfere with antigen-presenting cell (APC) activity of B cells subsequently decreasing T-cell activation, and (iii) the use of plasmapheresis (PE) + anti-cytomegalovirus (CMV) immunoglobulin G (IgG) or IVIG in lower doses. This protocol removes deleterious anti-HLA antibodies and may also allow complexing of anti-HLA with anti-idiotypes in the anti-CMV IgG. Although early, data support the efficacy of all three approaches. Many centers are now designing protocols that utilize a combination of all three agents. In summary, recent advances in the diagnosis and treatment of AMR has allowed for significant improvements in outcomes of a condition usually associated with rapid graft failure. However, much work needs to be done to better understand the immunologic processes leading to AMR and how current therapies can be best used to effectively prevent and treat it.

Intravenous Immunoglobulin Induction Treatment in Flow Cytometry Cross-Match—Positive Kidney Transplant Recipients

Many recent studies have demonstrated increased acute humoral, cellular, subclinical, or chronic rejection, and decreased allograft survival in flow cytometry cross-match-positive kidney transplant recipients. The use of newer techniques and more sensitive of enzyme-linked immunosorbent assay (ELISA) or Flow Beads (microparticle based methods), donor-specific anti-human leukocyte antigen (HLA) antibodies have been detected in these immunologically high-risk patients. Intravenous immunoglobulin (IVIG) has immunomodulatory effects and has been demonstrated to downregulate anti-HLA antibodies in highly sensitized dialysis patients awaiting transplantation. Our initial studies demonstrate that IVIG induction treatment is promising in flow cytometry cross-match-positive kidney transplant recipients, and thus, those patients should not be excluded from receiving transplantation despite a positive flow cytometry cross match. Further studies with long-term follow-up are required to determine the effective dose and duration of IVIG treatment, and additional studies are needed to determine the most accurate tests for risk stratification.

Post-transplant therapy with high-dose intravenous gammaglobulin: Applications to treatment of antibody-mediated rejection

B-cells and their products (antibodies) are now recognized as important mediators of allograft rejection. This represents a significant departure from previous doctrine where the T-cells were felt to be of paramount importance. Antibody-mediated rejection (AMR) has emerged as a significant and common complication of transplantation. The development of donor-specific (anti-HLA class I and class II) antibodies is known to correlate strongly with the development of AMR. Recognition of the unique features of AMR that were often confused with non-specific acute tubular injury is aided considerably by improvements in monitoring of anti-HLA antibodies and the immunopathologic demonstration of C4d staining in affected capillary beds. Although imperfect, the demonstration of C4d (a complement breakdown product) staining in an allograft, especially accompanied by the presence of anti-HLA antibodies in the recipient sera, strongly suggests a diagnosis of AMR. Thus, AMR is a complement-dependent, antibody-mediated disorder. AMR can occur as a de novo complication of transplantation in individuals not previously recognized to be sensitized to HLA antigens, but more often occurs as a complication of desensitization therapies in highly-HLA sensitized patients. AMR may also constitute a significant portion of what is now referred to as chronic allograft nephropathy (CAN). The prognosis of C4d (+) AMR is poor as current therapies for treatment of AR are directed primarily at the T-cell. Until recently, no therapeutic options existed to address this problem from a primary etiological standpoint. Here we discuss the use of high dose IVIG as an option for treatment of AMR. We have significant experience with this approach which is outlined here. IVIG has many ideal advantages as a therapy for AMR. First, it can down regulate B-cell activation and antibody production, second, it can induce anti-inflammatory cytokines and contains blocking antiidiotyic antibodies to anti-HLA antibodies and third, IVIG has the unique ability to block complement-mediated injury through inhibition of C3 activation. Further clinical trials are necessary to prove efficacy for treatment of AMR.

The efficacy of CD40 ligand blockade in discordant pig-to-rat islet xenotransplantation is correlated with an immunosuppressive effect of immunoglobulin

BACKGROUND

The authors' aim was to evaluate the efficacy of immunosuppression with monoclonal anti-CD40 ligand antibodies (aCD40L) or nonspecific polyclonal intravenous immunoglobulin (IVIG) in the pig-to-rat islet xenotransplantation model.

METHODS

Fetal porcine islet-like cell clusters were transplanted under the kidney capsule of nondiabetic rats. All antibodies were administered alone or in combination with cyclosporine A (CsA). In addition, some animals were administered antibodies plus tacrolimus (TAC) or sirolimus (SIR). Twelve days after transplantation, islet xenograft survival and rejection were evaluated using immunohistochemistry.

RESULTS

aCD40L plus CsA had a pronounced inhibitory effect on islet xenograft rejection for up to 12 days after transplantation. Unexpectedly, treatment with a monoclonal control antibody (anti-keyhole limpet hemocyanin [aKLH]) plus CsA had a similar inhibitory effect. Furthermore, a similar inhibition of islet xenograft rejection was observed also in animals administered IVIG plus CsA. Monotherapy with aCD40L, aKLH, IVIG, or CsA had no effect on the rejection process. Also, when aCD40L or aKLH was administered together with TAC, islet xenograft rejection was inhibited. There was no marked difference compared with rats treated with aCD40L or aKLH and CsA. Immunosuppression with aCD40L or aKLH in combination with SIR also inhibited pig-to-rat islet xenograft rejection, but the protective effect was not as pronounced.

CONCLUSIONS

Immunosuppression with high doses of antibodies, monoclonal or polyclonal, in combination with CsA or TAC inhibits pig-to-rat islet xenograft rejection. No specific effect of co-stimulatory blockade with aCD40L could be observed. Instead, the results indicate a nonspecific immunosuppressive effect of high doses of antibodies in this model.

Reversal of Acute Cellular Rejection After Renal Transplantation With Campath-1H

Between September 2002 and February 2004, 40 kidney transplant (27 from deceased and 13 from living donors) recipients (25 male and 15 female, aged 50.3 +/- 15.1 years) were treated with Campath 1H (C 1H; 30 mg/dose IV) for biopsy-proven steroid-resistant rejection (SRR) or rejections equal to or worse than Banff 1B. All transplantations occurred between August 2001 and May 2003. All patients had received antibody preconditioning (RATG 5 mg/kg, n = 34; C 1H 60 mg, n = 4; C 1H 30 mg, n = 2) preoperatively and were treated with Tacrolimus monotherapy (target level 10 ng/ml) postoperatively and subsequent spaced weaning. Elevated creatinine levels at follow-up were evaluated by renal transplant biopsy. Rejection was treated with steroids, reversal of weaning, addition of sirolimus, and/or antibody treatment, depending on grade of rejection. The mean duration of follow-up was 453 +/- 163 days after C 1H administration. Twenty-nine patients received C 1H for SRR and 11 patients for Banff 1B or worse rejections; 26 patients received more than 1 dose of C 1H. Graft survival was 62.5% (25 patients); 6 of the 15 allografts (40%) that failed had presented with rejections because of noncompliance. Graft survival in compliant patients with SRR or rejections equal to or worse than Banff 1B was 73.5% (25 of 34). Fourteen patients (35%) had infectious complications, of whom 2 patients (5%) died. C 1H is an effective agent for SRR and Banff 1B or worse rejections, with 95% patient survival and 73.5% graft survival (in compliant patients). The number of doses of 30 mg C 1H should be restricted to two, as there is a high incidence of potentially fatal infectious complications.

Immunological Strategies Targeting B Cells in Organ Grafting

After delayed-type hypersensitivity and T cell cytotoxicity, the production of alloantibodies is the third effector mechanism contributing to graft injury. Histological characterization of antibody-mediated rejection and the detection of donor-reactive antibodies have highlighted the role of humoral immunity in acute and chronic rejection. A potential way of achieving central B cell tolerance is to induce complete chimerism with a myeloablative regimen and bone marrow transplant. However, nonmyeloablative regimens have been developed to create a state of "mixed chimerism" in patients without hematologic malignancies. Other strategies targeting B cells have been developed for the management of "high risk" clinical situations, including highly sensitized patients and transplantation with a positive crossmatch. These strategies have been extended to ABO incompatible transplantations and xenotransplantations. We will review therapeutic regimens that allow the removal or neutralization of pathogenic antibodies (immunoadsorption, plasmapheresis, intravenous globulins) and the blockade of memory B cell proliferation and differentiation into plasmocytes, including cyclophosphamide, the tacrolimus/mycophenolate mofetil combination, and anti-CD20 antibodies.

Immunomodulatory Effects of Combination of Pooled Human Gammaglobulin and Rapamycin on Cell Proliferation and Apoptosis in the Mixed Lymphocyte Reaction

BACKGROUND

Multidrug immunosuppressive regimens benefit transplant recipients, reducing side effects and creating synergy between medications with different mechanisms of action. We have shown that pooled human gammaglobulin (intravenous immunoglobulin [IVIG]) inhibits the mixed lymphocyte reaction (MLR) and induces apoptosis primarily in B cells. Rapamycin (RAPA), a potent macrolide immunosuppressant, inhibits B- and T-cell proliferation through G1 cell-cycle blockade and purportedly induces apoptosis. Here we examined the possible synergistic effects of IVIG and RAPA on cell proliferation and apoptosis induction in the MLR.

METHODS

MLR was performed with IVIG (0.2-5 mg/mL), RAPA (0.02-40 ng/mL), alone or in combination. Cell proliferation was detected by H-thymidine incorporation, and apoptosis by Annexin V and terminal deoxynucleotide transferase-mediated dUTP nick-end labeling flow cytometry.

RESULTS

IVIG or RAPA inhibited cell proliferation in a dose-dependent manner. RAPA (0.02-40 ng/mL) in combination with IVIG (5 mg/mL) significantly augmented the inhibition compared with RAPA alone (70% vs. 34% at 0.2 ng/mL; 90% vs. 76% at 2 ng/mL). Apoptosis was significantly higher in IVIG-treated (5 mg/mL) CD19+ cells and less so in CD3+ cells. However, RAPA (0.2-40 ng/mL) neither induced apoptosis nor altered apoptosis induced by IVIG.

CONCLUSIONS

Combined RAPA and IVIG at subtherapeutic concentrations inhibits cell proliferation in the MLR. RAPA neither induces apoptosis nor augments apoptosis induced by IVIG in the MLR. Lower-concentration RAPA (0.2-2 ng/mL) in combination with IVIG (5 mg/mL) versus therapeutic levels (2-50 ng/mL and 10-40 mg/mL, respectively) could represent an effective immunomodulatory drug combination.

National conference to assess antibody-mediated rejection in solid organ transplantation

The process of humoral rejection is multifaceted and has different manifestations in the various types of organ transplants. Because this process is emerging as a leading cause of graft loss, a conference was held in April 2003 to comprehensively address issues regarding humoral rejection. Though humoral rejection may result from different factors, discussion focused on a paradigm caused by antibodies, typically against donor HLA antigens, leading to the term 'antibody-mediated rejection' (AMR). Conference deliberations were separated into four workgroups: The Profiling Workgroup evaluated strengths and limitations of different methods for detecting HLA reactive antibody, and created risk assessment guidelines for AMR; The Diagnosis Workgroup reviewed clinical, pathologic, and serologic criteria for assessing AMR in renal, heart and lung transplant recipients; The Treatment Workgroup discussed advantages, limitations and possible mechanisms of action for desensitization protocols that may reverse AMR; and The Basic Science Workgroup presented animal and human immunologic models for humoral rejection and proposed potential targets for future intervention. This work represents a comprehensive review with contributions from experts in the fields of Transplantation Surgery, Medicine, Pathology, Histocompatibility, Immunology, and clinical trial design. Immunologic barriers once considered insurmountable are now consistently overcome to enable more patients to undergo organ transplantation.

INTRAVENOUS IMMUNOGLOBULIN: A SAFE OPTION FOR TREATMENT OF STEROID-RESISTANT REJECTION IN THE PRESENCE OF INFECTION

Management of recurrent allograft rejection is a risky proposition, especially in the presence of infections. Both steroids and antibody therapy worsen the infection risk. We successfully treated steroid-resistant rejection with intravenous immunoglobulin (IVIG) in two patients who had concomitant infections. IVIG should be considered the treatment of choice for management of steroid-resistant rejection in the presence of serious infection.

The role of B cells and alloantibody in the host response to human organ allografts

Some human organ transplants deteriorate slowly over a period of years, often developing characteristic syndromes: transplant glomerulopathy (TG) in kidneys, bronchiolitis obliterans in lungs, and coronary artery disease in hearts. In the past, we attributed late graft deterioration to "chronic rejection", a distinct but mysterious immunologic process different from conventional rejection. However, it is likely that much of chronic rejection is explained by conventional T-cell-mediated rejection (TMR), antibody-mediated rejection (AMR), and other insults. Recently, criteria have emerged to now permit us to diagnose AMR in kidney transplants, particularly C4d deposition in peritubular capillaries and circulating antibody against donor human leukocyte antigens (HLA). Some cases with AMR develop TG, although the relationship of TG to AMR is complex. Thus, a specific diagnosis of AMR in kidney can now be made, based on graft damage, C4d deposition, and donor-specific alloantibodies. Criteria for AMR in other organs must be defined. Not all late rejections are AMR; some deteriorating organs probably have smoldering TMR. The diagnosis of late ongoing AMR raises the possibility of treatment to suppress the alloantibody, but efficacy of the available treatments requires further study.

Intravenous immune globulin treatment inhibits crossmatch positivity and allows for successful transplantation of incompatible organs in living-donor and cadaver recipients

BACKGROUND

Sensitization to human leukocyte antigens (HLA) is a significant barrier to transplantation. Currently, no proven therapy exists to improve access to transplantation for highly sensitized patients. Here, we report a novel approach using intravenous immune globulin to modulate anti-HLA antibody and improve the chances for successful transplantation.

PATIENTS AND METHODS

Forty-five highly HLA-sensitized patients presented as candidates for living-donor kidney transplantation (n=28), cadaveric kidney transplantation (n=15), or heart transplantation (n=2). All patients had a positive CDC crossmatch (CMX) with their donors. In living-donor recipients, intravenous immune globulin (IVIG) was added to the CMX evaluation to determine whether blocking antibodies present in IVIG could inhibit cytotoxicity. For those who showed in vitro inhibition with IVIG (n=26), IVIG was administered (usually as a single dose, 2 g/kg) and the CDC CMX was repeated against the prospective donor immediately after IVIG infusion. If negative, the patient underwent transplantation with their living-donor kidney within 24 to 72 hr. A similar but modified protocol was performed for cadaver donor candidates, all of whom were highly sensitized and had had CMX positivity with multiple donors, negating transplantation. Reductions in CMX positivity, posttransplantation serum creatinine level, number and severity of rejection episodes, and patient and graft survival rates were determined.

RESULTS

Forty-two patients underwent transplantation. IVIG treatment completely abrogated the donor-specific CMXs in 35 of 42 patients. In the remaining 7 patients, the CDC CMX was inhibited, but flow cytometry CMXs remained positive. A total of 13 (31%) of 42 recipients developed rejection episodes 3 to 49 days after transplantation. Three grafts (7%) were lost to rejection. Mean serum creatinine level at 24 months was 1.4+/-0.4 mg/dL. Patient and graft survival rates were 97.6% and 89.1%, respectively, at 24 months.

CONCLUSIONS

The in vitro IVIG CMX technique predicts the ability of IVIG to reduce anti-HLA antibody levels in highly sensitized patients. Subsequent in vivo IVIG treatment of responders eliminates the positive CDC CMX and allows for successful transplantation. Thus a positive CMX result is not necessarily a contraindication for transplantation and allows access to transplantation for patients for whom it was previously contraindicated.

Utility of intravenous immune globulin in kidney transplantation: efficacy, safety, and cost implications

Intravenous immunoglobulin preparations (IVIG) are known to be effective in the treatment of various autoimmune and inflammatory disorders into their immunomodulatory, immunoregulatory, and anti-inflammatory properties. Recently, IVIG has been utilized in the management of highly sensitized patients awaiting renal transplantation. The mechanisms of suppression of panel reactive antibodies (PRA) in patients awaiting transplantation are currently under investigation and appear to be related to anti-idiotypic antibodies present in IVIG preparations. In this review, the various immunomodulatory mechanisms attributable to IVIG and their efficacy in reducing PRAs will be described. In addition, the use of IVIG in solid organ transplant recipients will be reviewed. The adverse events, safety considerations, and economic impact of IVIG protocols for patients awaiting solid organ transplantation will be discussed.

Therapy for acute rejection in pediatric organ transplant recipients

Despite the availability of potent immunosuppressive drugs, rejection after organ transplantation in children remains a serious concern, and may lead to significant morbidity, graft loss, and death of the patient. Acute graft rejection in pediatric recipients is first treated with methylprednisolone pulses, followed by progressive taper of corticosteroid doses. After control of the rejection episode, baseline immunosuppression has to be adjusted and closely monitored since rejection (especially late episodes, occurring more than 6 months after transplantation) may be due to a lack of compliance or sub-therapeutic drug concentrations. The management of corticosteroid resistant rejection is not standardized, and depends on the transplanted organ and previous immunosuppressive regimen. In patients experiencing corticosteroid resistant acute rejection while on a cyclosporine-based immunosuppressive regimen, cyclosporine is generally changed to tacrolimus. In case of tacrolimus-based immunosuppression, tacrolimus blood levels may be increased, and/or mycophenolate mofetil (which nowadays tends to replace azathioprine) or sirolimus may be added, although pharmacodynamic data and clinical studies with these agents are still scarce in pediatric recipients. The use of antithymocyte globulins or monoclonal anti-CD3 antibodies, muromonab CD3 (OKT3) is hampered by numerous adverse effects, including a significant risk of over-immunosuppression. These therapies are nowadays indicated in very selected cases. Other treatments such as plasmapheresis and high dose immunoglobulins may be useful in difficult cases. In patients with refractory rejection despite therapeutic escalation, the risks of over-immunosuppression, including opportunistic infections and malignancies (especially the Epstein-Barr virus related post-transplant lymphoproliferative disease) have to be balanced with the consequences of graft loss due to rejection. Detransplantation or retransplantation may, in some instances, be preferable to severe infectious or tumoral complications.

Pooled human gammaglobulin modulates surface molecule expression and induces apoptosis in human B cells

We have previously shown that the pooled human gammaglobulin (IVIG) inhibited mixed lymphocyte reaction (MLR). In this study, we examined (1) if IVIG contains blocking antibodies reactive with cell surface molecules required for alloantigen recognition and (2) if IVIG modulates these surface molecule expressions using flow cytometry. IVIG does not contain significant amounts of blocking antibodies against CD3, CD4, CD8, CD20, CD14, CD40, MHC class I and class II. It reduces the number of intact B cells and monocytes, reduces or modulates CD19, CD20 and CD40 expression on B cells, and induces morphological changes in B cells. This B-cell modulation results primarily because of apoptosis. IVIG also induces apoptosis in T cells and monocytes, but to a lesser degree. Induction of apoptosis requires the intact IgG molecule. Reduction of intact B cell and monocyte cell numbers, modulation of surface molecule expression on B cells, and deletion of B and T cells by apoptosis could result in inhibition of optimal T-cell activation. This likely represents the primary mechanism responsible for IVIG suppression of the MLR, and may account for many of the observed beneficial effects of IVIG seen in the treatment of human autoimmune and alloimmune disorders.

Individualized T cell monitored administration of ATG versus OKT3 in steroid-resistant kidney graft rejection

Acute steroid-resistant rejection episodes are recommended to be treated with set doses of anti-thymocyte globulin (ATG) or anti-CD3 monoclonal antibody (OKT3). Individualized T cell monitoring has been proposed as a tool for dose finding. A randomized study comparing the efficacy and safety of ATG (n = 27) with OKT3 (n = 28) in the treatment of biopsy verified acute steroid-resistant rejection (ASRR) when both drugs were administered on the basis of daily individualized T cell measurements. A drop to below 50 cells/mm3 CD2+ T cells was considered adequate and used to guide the dose of ATG/OKT3. Demographic, clinical and histopathological severities of rejections were equal in the two groups. During the 10 days of T cell monitoring and antibody treatment, 13 patients were in need of dialysis (ATG = 7/OKT3 = 6). Two grafts did not respond to antibody treatment and were lost due to rejection (ATG = 1/OKT3 = 1). There were 26 biopsy verified re-rejections (ATG = 12/OKT3 = 14) within the first 3 months following antibody treatment. Mean serum creatinine (micromol/L) was similar in the two groups (ATG/OKT3: before rejection 157 +/- 72/151 +/- 88, at start of antibody treatment 308 +/- 125/330 +/- 94, end of antibody treatment 254 +/- 122/246 +/- 144 and at follow-up after a mean of 32 months 166 +/- 55 (n = 24)/164 +/- 57(n = 23)). To keep the T cell count below 50 cells/mm3, average dose ATG given was 354 +/- 151 mg (2.3 administrations, range 1-4) and average OKT3 was 32.5 +/- 6.8 mg in 10 doses. In conclusion, individualized T cell monitored administration of ATG and OKT3 is safe and seems as effective as a standard set dose in treatment of ASRR. Tailoring the dose for each individual patient lowers the cost.

Successful renal transplant outcome after intravenous gamma-globulin treatment of a highly sensitized pediatric recipient

Approximately 10% of patients on the renal transplant (Tx) cadaver waiting list have high (> 20%) panel-reactive antibody (PRA) levels to human leukocyte antigens (HLA). Intravenous gamma-globulin (IVIG) has been shown to reduce anti-HLA cytotoxic antibody levels through an anti-idiotypic antibody-blocking effect. We report a successful renal Tx outcome in a 7-yr-old-girl with high PRA levels owing to a failed renal Tx who experienced a significant reduction in PRA levels (from 96% to 0%) concomitant with IVIG therapy. IVIG was infused weekly (500 mg/kg/week) for 3 consecutive weeks every 12 weeks. Thirty-four months after starting IVIG therapy, the PRA activity dropped to zero and IVIG was stopped. Then IVIG therapy was resumed after 8 months due to a rebound in PRA activity to 52%. Forty-four months after starting IVIG therapy, the patient was cross-matched with a cadaver donor who shared three antigens with the first living donor. The cross-match was positive with the recipient's sera obtained prior to IVIG therapy and negative with the recipient's sera obtained post-IVIG therapy. A successful cadaver renal Tx was performed using anti-thymocyte globulin (ATGAM) induction therapy and a tacrolimus-based immunosuppression protocol. IVIG was given (1 g/kg) prior to Tx and at day 4 post-operatively. A single mild acute rejection episode occurred 10 days post-transplantation that responded to pulse methylprednisolone therapy and an increase in the tacrolimus oral dose. We conclude that a prolonged course of IVIG infusions, without immunosuppressive medications or plasmapheresis, is likely to have been beneficial in modulating the immune response in this highly sensitized recipient. Randomized multicenter trials are required to define the role of IVIG in this specific population.