Infection following haematopoietic stem cell transplantation

Haematopoietic stem cell transplantation is offered to increasing numbers of patients, with the potential of curing underlying disease. Whilst survival rates have significantly improved over recent years, with survival for some procedures over 90%, infection remains a significant cause of morbidity and mortality. Strategies to improve the outcome of patients who develop infection through the transplant period are being introduced. Minimal intensity conditioning regimens reduce the period of bone marrow aplasia when patients are most at risk of developing life-threatening bacterial or fungal infection. Reduction or omission of serotherapy as part of the conditioning regimen preserves donor lymphocytes and results in more rapid viral clearance. Weekly surveillance for herpes- and adenovirus infection enables pre-emptive treatment before disease develops – new antiviral treatments are currently being trialled. Cellular therapies are more effective at countering viral infection. New methods of graft manipulation remove T lymphocytes more likely to cause GvHD, but retain Natural Killer cells and specific T lymphocyte subsets more likely to exhibit antiviral activity. Immunomodulatory methods of treating graft-versus host disease enable a reduction in conventional immunosuppression, which allows control of viral infection. New methods of generating virus-specific cytotoxic T lymphocytes will facilitate donor banking of such cells to treat patients with third party lymphocyte infusions.