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:

• Blood group testing: Both donor and recipient must be compatible with the blood type. Group O is the universal donor.
• Serum crossmatch: Donor cells and recipient serum mix if there are antibodies against the graft they will attack and destroy the donor cells, so it is a positive test, and the transplant surgery cannot perform.
• HLA typing: It must test for histocompatibility between donor and recipient. The most critical loci are HLA-A, HLA-B, and HLA-DR.

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.[7] 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[8].

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.[9] 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[10].

• Liver transplantation: There is a tendency for bleeding. It is a complicated surgery in which the surgeon must revascularize a grafted liver. However, rejection episodes are milder and require less immunosuppression.
• Skin grafting: Used to treat severely burned patients; HLA typing is not done in practice because of the endogenous immunosuppressive effect of severe burns.
• Corneal grafting: There is no need for HLA typing. Corneas are obtained from cadaveric donors.
• Heart transplantation: The use of cyclosporin improves the survival of this graft. It requires ABO compatibility but not HLA typing. Serial endomyocardial biopsies that show increased HLA class I expression by myocardial cells suggests early rejection. It speeds up a major post-operative problem: atherosclerosis in the graft coronary arteries, which is a cause of death in those that survive over 1 year.
• Lung transplantation: It is indicated for chronic airways disease, cystic fibrosis, and another potentially fatal lung diseases. Acute rejection is a leading cause of death in this transplantation. Current immunosuppressive regimen and best practice surgical operation give a 3-year survival of over 50%. Infection is a common cause of death.
• Pancreatic transplantation: Graft survival correlates with HLA compatibility. Transplantation of isolated islets is more successful to reduce their immunogenicity.

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.