Transplantation is the only mode of therapy for most end-stage organ failure affecting kidneys, liver, heart, lungs, and pancreas. Acute transplantation rejection occurs days to weeks after transplantation. The immune system can see the grafted organ as foreign and attacks it; destroying it leading to rejection. The difference between hyperacute and acute graft rejection lays in the presence of preformed antibodies that cause rejection immediately. HLA matching is 1 of 2 critical methods for preventing rejection of allografts, and the other one is the serum crossmatch. Using immunosuppressive drugs, for example, azathioprine and corticosteroids can prevent acute rejection. The induction of tolerance in alloreactive donor cells is a goal of transplantation and a method to prevent rejection of organs and tissues. The deficit of donor organs limits the success of transplantation in humans, and an alternative is the use of pigs (xenotransplantation), and living donations is another way of tackling the problem.
In renal transplantation matching of MHC class II antigens are more critical than MHC class I antigen compatibility in determining graft survival. Matching of the ABO blood group system is also essential since A and B antigens can express on endothelium. When there is a genetical disparity between donor and receptor, MHC class I and II can see as foreign by the immune system. CD4+ T cells react to these donor antigens presented by antigen-presenting cells (APC) or themselves and produce cytokines that stimulate a robust immune reactivity that destroy the graft within days or weeks.
In renal transplantation, acute rejection rates have dramatically fallen, chiefly due to the use of immunosuppressives such as calcineurin inhibitor regimes. The long-term outcome has improved. A delayed graft function is a preponderant risk factor for acute rejection that can be due to vulnerability or prolonged preservation times of allografts.
It can associate acute rejection with increased expression of HLA class I and class II antigens in inflamed grafts and with early infiltration of CD8+ T cells. Fine-needle aspiration can help recognize rejection from cyclosporin toxicity. CD4+ T cells orchestrate rejection by recruiting a range of effector cells responsible for the damage of rejection including CD8+ T cells, macrophages, natural killer cells, and B cells. Foreign antigens can recognize these in the graft or the lymphoid tissue of the recipient. Another histopathologic mechanism is the participation of dendritic cells which are antigen-presenting cells of the donor tissue or organ that migrate to the recipient's lymphoid follicles and present peptides to the recipient's adaptive immune system causing acute rejection. Alloreactive cytotoxic T lymphocytes (CTLs), have CD8 molecules that bind to the transplanted tissue's MHC class I proteins that express the donor's self-peptides and then CTLs cause a graft tissue damage, featuring rejection.
Acute rejection relates well with class I and class II HLA gene disparity between donor and receptor. ABO matching protects against hyperacute transplantation rejection, which cannot prevent with the use of immunosuppressive drugs. However, children below 24 months of age can accept incompatible organs without rejecting it, ABO-incompatible (ABOi) transplantation. Immaturity of the immune system causes this unresponsive mechanism against graft tissues.
Memory cells against the graft alloantigens differentiate into Th1 and Th2 lymphocytes. Th1 cells produce IL-2 and gamma interferon that mediates cellular immune responses including activation of macrophages against the allograft and xenograft. Th2 cells produce IL-4, IL-5, IL-6, IL-10 and IL-13 that stimulates humoral responses (mediated by antibodies) against the graft. However, Th1 cells orchestrate the acute graft rejection. Other T cell subsets that may be involved in rejection are Th9, Th17, and Th22 through participation in the inflammatory response.
Histologically, there is a mononuclear infiltrate in the renal cortex, and necrosis of arterial walls; after successful treatment, the inflammatory infiltrate clears. Graft-versus-host disease is a usual complication of allograft; skin biopsy shows lymphocytic infiltration with vascular cuffing and basal cell degeneration. Summarizing a pathologist will make a diagnosis of acute rejection based on infiltrating T cells, structural compromise of tissue anatomy that varies by the graft used, and blood vessel damage.
Diagnosis of acute rejection bases on clinical data including the patient symptoms and signs and confirmed by laboratory studies of blood and tissue biopsy. There is a history of an end-stage chronic illness, for example, diabetic nephropathy. After a few days or weeks of successful transplantation surgery, the patient complains about tenderness at the site of the graft, pyrexia, and abnormal function of the organ or tissue graft, for example, in renal transplantation appears anuria, an increasing serum creatinine levels and metabolic problems including hyperkalemia.
A rejected pancreas may manifest by the production of a little amount of insulin, which is not sufficient for healthy glucose metabolism. A rejected lung shows hypercapnia and hypoxia. Acute rejection can associate with a high incidence of infections and other complications as the lethal graft-versus-host disease. It can recognize a single episode of acute rejection and promptly treated, often preventing organ or tissue failure, but recurrence can lead to chronic rejection.
A clinical diagnosis of acute graft rejection is confirmed by a finding of lymphocytic infiltration of the renal cortex on fine-needle aspiration. If transplantation is unsuccessful, a retransplantation surgery should consider, and the patient must do the following tests:
Acute rejection occurs in all transplants, except between identical twins. Acute rejection begins as early as one week after transplant, the risk being highest in the first three months,After favorable histology or clinical suspicion of acute renal rejection, therapy should start with a 3-day course of intravenous methylprednisolone, and periodically testing of serum creatinine levels. Subsequently, if the patient has similar rejection episodes post-operatively, the practitioner should treat with intravenous corticosteroids. In a patient that does well, cyclosporin-A should discontinue after 9 months, but the patient still should take a daily maintenance dose of immunosuppressive drugs, for example, 50-mg azathioprine and 5-mg prednisolone.
Retransplantation should consider on laboratory and clinical basis where there is not a definite improvement despite all efforts. Primary cytomegalovirus (CMV) infection in the recipient due to transplantation of a CMV-positive kidney into a CMV-negative recipient can treat with a combination of ganciclovir and CMV-specific immune globulin. Cases refractory to immunosuppressive or intravenous antibody can treat with extracorporeal photoimmune therapy to inactivate graft-specific immunoglobulins.
Cytologic examination of voided urine is the simple diagnostic method for the differentiation between allograft rejection and CMV-infection. IgM anti-CMV antibodies can be detected and confirm the diagnosis of CMV infection. Adenovirus nephropathy may mimic allograft rejection and can rule out by PCR of the blood.
The FTY 720 (fingolimod) is an immunosuppressive agent. FTY is highly effective in prolonging graft survival in clinical studies of transplantation. It is an immunomodulator and differs entirely from traditional immunosuppressants. Fingolimod is a new class of drugs named sphingosine 1-phosphate receptor (S1P-R) modulators. This drug has shown promising results for the use of other immunological problems such as multiple sclerosis.
The prognosis of a patient with acute rejection is guarded. However, the long-term prognosis is good in individuals with none or little genetical mismatch, for example, twins. The prognosis in those with acute rejection that are non-genetically related can better with introducing immunosuppressive drugs. The prognosis of an autograft is the best and does not require the use of immunotherapy.
Graft-versus-host disease should suspect after organ transplantation between genetically unrelated individuals. It is a complication of organ transplantation and clinically characterized by rash, fever, bloody diarrhea, hepatosplenomegaly, and breathlessness 7 to 14 days after transplantation. The rash can progress to exfoliative dermatitis.
Susceptibility to infection is also a complication of acute rejection that can be a cause of death. Infection may be bacterial, viral, fungal, protozoal, or mixed. It often relates infection with CMV with graft rejection.
A late complication of particular renal transplantation is the recurrence of the original disease that should be suspected when alternating functional deterioration with long periods of stable graft function. Malignancy in the recipient is another late complication, e.g., the incidence of lymphoma and skin cancer is higher in transplant recipients.
Patients must comply with the treatment of comorbidities including renal disease, diabetes mellitus, and cystic fibrosis, among others. It must educate patients to take immunosuppressive drugs needed to avoid organ rejection and improve their quality of life. Rejection caused by non-adherence affect 50% of the adolescent in some countries.
An interprofessional team educates and manages the patient with acute rejection. Health care providers should advise the patient about treatment options and offer psychological support. Acute rejection is very common but if the diagnosis is made early, the graft can be preserved with treatment. However, constant monitoring is required to 1) assess the function of the graft and 2) prevent further graft rejections.