Mechanisms of immune dysfunction in stem cell transplantation

James E. Talmadge, Rakesh Singh, Kazuhiko Ino, Ana Ageitos, Suleyman Buyukberber

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

High dose therapy (HDT) and stem cell transplantation (SCT) results in alterations in the immunologic network, thymic re-education and the induction of peripheral tolerance. The changes to the immunoregulatory cascade and tolerance induction associated with autotransplants have been investigated in a series of studies focused on leukocyte reconstitution and function following HDT and autologous SCT. In these studies, we observed a significant decrease in the CD4:CD8 T cell ratio post-transplantation compared to normal peripheral blood (PB) donors due to a decrease in CD4+ cells. In addition, T cell function (phytohemagglutinin (PHA) mitogenesis) was consistently depressed compared to samples obtained from normal PB donors. The loss of T cell function was associated with an increased frequency of circulating monocytes, their expression of Fas ligand (FasL) and a high frequency of apoptotic CD4+ T cells. Indeed, 28-51% of circulating CD4+ T cells were observed to be apoptotic during the first 100 days following HDT and SCT. These studies suggest that 'primed' or activated Fas+ CD4+ lymphocytes interact with FasL+ monocytes, resulting in apoptosis, leading to the preferential deletion of CD4+ T cells, a decrease in the CD4:CD8 T cell ratio and depressed T cell function. Further, as discussed herein, the T cells are activated with a predominantly type 2 phenotype, which may also contribute to the maintenance of the immunosuppressive condition. Therefore, there is the potential to regulate immune recovery by stem cell product manipulation or post-transplantation cytokine administration.

Original languageEnglish (US)
Pages (from-to)1041-1056
Number of pages16
JournalInternational Journal of Immunopharmacology
Volume22
Issue number12
DOIs
StatePublished - 2000

Keywords

  • Immune regulation
  • Peripheral tolerance
  • T cell function

ASJC Scopus subject areas

  • Immunology
  • Pharmacology

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