Reversal of graft-versus-host disease with infusion of autologous bone marrow

Immunological basis for treatment of graft versus host disease after liver transplant

Graft versus host disease (GVHD) after liver transplant, although a rare disease, has a very high mortality rate. GVHD occurs due to immunoreactions caused by donor T lymphocytes and host cell surface antigens resulting in proliferation and clonal expansion of T lymphocyte. Migration of effector cells, including macrophages, NK cells and cytotoxic T lymphocyte, to the target organs such as skin, intestine and bone marrow results in skin rashes, diarrhea and bone marrow depression. GVHD is diagnosed by clinical symptoms, histopathological findings and by the presence of chimerism. The delayed diagnosis, opportunistic infections and lack of definitive treatment of post orthotopic liver transplant (OLT)-GVHD results in sepsis and multi-organ failure leading to very low survival rates. In this review, we have focused on early diagnosis and critically discuss novel treatment modalities to decrease the incidence of GVHD.

Treatment of liver transplant graft-versus-host disease with antibodies against tumor necrosis factor-α

Acute graft-versus-host disease is uncommon after liver transplant. We recently treated a 60-year-old man with liver transplant for hepatocellular carcinoma. After the primary liver transplant graft did not function, revision liver transplant resulted in excellent function. Subsequently, the patient developed watery diarrhea, systemic inflammatory response syndrome, a skin rash on his limbs and trunk, and palmar erythema. Skin biopsy suggested viral exanthems consistent with cytomegalovirus. Despite treatment for cytomegalovirus, intestinal symptoms worsened. Analysis of peripheral blood with fluorescence-activated cell sorting showed a high proportion of T lymphocytes, with 5% to 10% T cells specific to the second donor, suggestive of graft-versus-host disease. Within 48 hours after beginning therapy with antibodies against tumor necrosis factor-α (infliximab), the skin rash disappeared and endoscopy showed slight improvement of the mucosal regeneration. However, despite antifungal prophylaxis with caspofungin, the patient developed angioinvasive pulmonary aspergillosis and multiple organ failure, and he died. In conclusion, typical clinical symptoms of graft-versus-host disease after liver transplant may include skin rash and gastrointestinal symptoms, and diagnosis may be confirmed by histologic examination and testing for blood chimerism. A consensus for the treatment of graft-versus-host disease still is lacking, but tumor necrosis factor-α is an encouraging target for therapy to decrease the symptoms of graft-versus-host disease and enable mucosal regeneration.

Graft vs. host disease after liver transplantation: a new approach is needed

Graft-vs.-host disease (GVHD) is a rare, serious complication of orthotopic liver transplantation (OLT). We have treated 5 patients to date with GVHD after OLT. A total of 78 patients worldwide have been reported to have experienced this complication. The means by which GVHD after OLT has been managed is guided by experience with the more common GVHD that occurs after stem cell transplantation. However, despite the use of various treatment modalities, the mortality of GVHD after OLT remains high. This case series and review of the literature demonstrates that successful resolution of GVHD after OLT cannot be expected with the use of those modalities that have been tried to date. It is imperative that new treatments be applied to GVHD after OLT in order to improve the prognosis of patients with this diagnosis.

Acquired immunologic tolerance: with particular reference to transplantation

The first unequivocally successful bone marrow cell transplantation in humans was recorded in 1968 by the University of Minnesota team of Robert A. Good (Gatti et al. Lancet 2: 1366-1369, 1968). This achievement was a direct extension of mouse models of acquired immunologic tolerance that were established 15 years earlier. In contrast, organ (i.e. kidney) transplantation was accomplished precociously in humans (in 1959) before demonstrating its feasibility in any experimental model and in the absence of a defensible immunologic rationale. Due to the striking differences between the outcomes with the two kinds of procedure, the mechanisms of organ engraftment were long thought to differ from the leukocyte chimerism-associated ones of bone marrow transplantation. This and other concepts of alloengraftment and acquired tolerance have changed over time. Current concepts and their clinical implications can be understood and discussed best from the perspective provided by the life and times of Bob Good.

Mechanisms of the antitumor responses and host-versus-graft reactions induced by recipient leukocyte infusions in mixed chimeras prepared with nonmyeloablative conditioning: a critical role for recipient CD4+ T cells and recipient leukocyte infusion-derived IFN-gamma-producing CD8+ T cells

Surprisingly, antitumor responses can occur in patients who reject donor grafts following nonmyeloablative hemopoietic cell transplantation. In murine mixed chimeras prepared with nonmyeloablative conditioning, we previously showed that recipient leukocyte infusions (RLI) induced loss of donor chimerism, IFN-gamma production, and antitumor responses against host-type tumors. However, the mechanisms behind this phenomenon remain to be determined. We now demonstrate that the effects of RLI are mediated by distinct and complex mechanisms. Donor marrow rejection is induced by RLI-derived alloactivated T cells, which activate non-RLI-derived, recipient IFN-gamma-producing cells. RLI-derived CD8 T cells induce the production of IFN-gamma by both RLI and non-RLI-derived recipient cells. The antitumor responses of RLI involve mainly RLI-derived IFN-gamma-producing CD8 T cells and recipient-derived CD4 T cells and do not involve donor T cells. The pathways of donor marrow and tumor rejection lead to the development of tumor-specific cell-mediated cytotoxic responses that are not due to bystander killing by alloreactive T cells.

Microchimerism, GVHD, and tolerance in solid organ transplantation

The phenomenon of microchimerism and its relationship to long-term graft tolerance is an area of active study. The ability to establish a tolerant state has been enhanced with current immunosuppressive drugs and emerging therapies such as donor HPC infusions. An undesirable outcome of host-donor WBC interaction is GVHD. GVHD is a rare complication reported most frequently in liver transplantation. Two cases of GVHD reported in recipients of organs from donors homozygous for a shared HLA haplotype would support a policy of avoiding the use of these donors. TA-GVHD is very rare in solid organ transplant recipients, with only four published cases; only two had convincing supportive evidence and one of these had an underlying hematologic abnormality. These few cases do not support a policy of routine irradiation of cellular blood components for all solid organ transplant recipients. The use of donor HPC infusions to enhance chimerism and graft tolerance has increased the number of GVHD cases observed (usually mild) and decreased the severity and number of rejection episodes. The long-term effects of donor HPC infusions on graft survival is under investigation.

Unusual presentation of graft-versus-host disease in pediatric liver transplant recipients: evidence of late and recurrent disease

Graft-versus-host disease (GvHD) is a multi-organ disease caused by mature donor T cells that are activated by alloantigens expressed by the host antigen-presenting cells. GvHD has been reported after solid organ transplantation with two principal presentations: humoral and cellular. In the cellular type of GvHD after liver transplantation the symptoms are identical to the GvHD after bone marrow transplant, except that the liver is spared because it lacks host antigens. We have described three cases of intestinal GvHD after pediatric liver transplant with an unusual recurrent late presentation in two patients. Two patients were female, and their age at the time of transplant was 8 and 9 months, respectively, and one was an 8-month-old male. They all received reduced liver allografts of identical blood type from three different donors. One patient received two doses of donor bone marrow cell infusion. Two patients received double immunosuppressive therapy constituted by tacrolimus at a dose of 0.05 mg/kg p.o. b.i.d. and steroids 10 mg p.o. daily. One patient received a triple drug immunosuppression with tacrolimus (0.05 mg/kg p.o. b.i.d.), steroids (10 mg p.o. daily) and mycophenolate mofetil (125 mg p.o. b.i.d.). Diagnosis of intestinal GvHD was confirmed histologically on intestinal biopsies performed at the time of presentation of the clinical symptoms or at autopsy.

Acquired transplant tolerance

Increasing the acceptance rate of organs is the central goal of transplantation research. Long-term survival of vascularized organs without chronic immunosuppressive therapy has been achieved in experimental animals. In humans, the possibility of achieving immunological tolerance and a drug-free state has been reported occasionally in patients who after withdrawal of immunosuppressants because of major toxicity still carry a functioning graft. It has been proposed that organ transplant implies a migratory flux of donor 'passenger' leukocytes out of the graft into the recipient tissue or organs, to establish a persistent condition of 'microchimerism'. Although there is evidence that the same migratory mechanisms apply to all organ grafts, migration of 'passenger' leukocytes is less in kidney and heart than in liver. To enhance the acceptance of organs less tolerogenic than liver, perioperative infusion of donor bone marrow has been attempted to increase the donor 'passenger' leukocyte load. It has been suggested that the established microchimerism is not only associated with long-term acceptance of the graft, but it also plays an active role in induction and maintenance of donor-specific unresponsiveness. However, the intimate mechanism(s) responsible for prolonged graft survival in this setting remain speculative. Experimental evidence is also available that the thymus plays a major role in the development of self-tolerance and is critical in the induction of acquired tolerance to exogenous antigens. It has been reported that after intrathymic injection of donor cells clonal deletion of maturing thymocytes occurs and is the major mechanism in the induction of donor-specific tolerance, since peripheral T-cell component would be devoid of alloreactive population. Studies are warranted in the near future to explore whether the thymus technique can be employed to prolong survival or induce tolerance to allograft in humans. An interesting novel strategy for transplant tolerance is also the oral administration of alloantigens, which has been recently applied to the cardiac transplant model in rat. All these approaches will have a major impact in the near future on transplant medicine, opening new perspectives to obtain indefinite graft survival.