immunology allergic disorders
Hematopoietic Stem Cell Transplantation
Complications of Hematopoietic Stem Cell Transplantation
(See also Posttransplantation Complications .) Complications of stem cell transplantation can occur early (< 100 days after transplantation) or later. After allogeneic hematopoietic stem cell transplantation, risk of infections is increased. Major early complications include Failure to engraft Graft rejection and graft-vs-host disease None Acute graft-vs-host disease (GVHD) Failure to engraftandrejectionaffect<5% of patients and manifest as persistent pancytopenia or irreversible decline in blood counts. Treatment is corticosteroids for several weeks. Acute GVHD,in which immune cells from the donor attack tissue in the recipient, occurs in recipients of allogeneic hematopoietic stem cell transplants (in 40% of HLA-matched sibling graft recipients and 80% of unrelated donor graft recipients). It causes fever, rash, hepatitis with hyperbilirubinemia, vomiting, diarrhea, abdominal pain (which may progress to ileus), and weight loss. Risk factors for acute GVHD include HLA and sex mismatching Unrelated donor Older age of recipient, donor, or both Donor presensitization Inadequate GVHD prophylaxis Diagnosis of acute GVHD is obvious based on history, physical examination, and liver test results. Treatment ismethylprednisolone2 mg/kg IV once a day, increased to 10 mg/kg if there is no response within 5 days. Major later complications include Chronic GVHD Disease relapse Chronic GVHDmay occur by itself, develop from acute GVHD, or occur after resolution of acute GVHD. It typically occurs 4 to 7 months after hematopoietic stem cell transplantation (range 2 months to 2 years). Chronic GVHD occurs in recipients of allogeneic hematopoietic stem cell transplants (in about 35 to 50% of HLA-matched sibling graft recipients and 60 to 70% of unrelated donor graft recipients). Chronic GVHD affects primarily the skin (eg, lichenoid rash, sclerotic skin changes) and mucous membranes (eg, keratoconjunctivitis sicca, periodontitis, orogenital lichenoid reactions), but it also affects the gastrointestinal tract and liver. Immunodeficiency is a primary feature; bronchiolitis obliterans similar to that after lung transplantation can also develop. Ultimately, GVHD causes death in 20 to 40% of patients who have it. Treatment may not be necessary for GVHD that affects the skin and mucous membranes; treatment of more extensive disease is similar to that of acute GVHD. T-cell depletion of allogeneic donor grafts using monoclonal antibodies or mechanical separation reduces incidence and severity of GVHD but also eliminates the graft-vs-tumor effect that may enhance stem cell proliferation and engraftment and reduce disease relapse rates. Relapse rates with autologous hematopoietic stem cell transplantation are higher because there is no graft-vs-tumor effect and because circulating tumor cells may be inadvertently collected with stem cells and transplanted. Ex vivo tumor cell purging before autologous transplantation is under study. In patients without chronic GVHD, all immunosuppression can be stopped 6 months after hematopoietic stem cell transplantation; late complications are rare in these patients. 