IL-7 increases both thymic-dependent and thymic-independent T-cell regeneration after bone marrow transplantation

Crystal L. Mackall, Terry J. Fry, Cathy Bare, Paul Morgan, Anne Galbraith, Ronald E. Gress

Research output: Contribution to journalArticlepeer-review

252 Scopus citations


Thymic-dependent differentiation of bone marrow (BM)-derived progenitors and thymic-independent antigen-driven peripheral expansion of mature T cells represent the 2 primary pathways for T-cell regeneration. These pathways are inter-regulated such that peripheral T-cell expansion is increased in thymectomized versus thymus-bearing hosts after bone marrow transplantation (BMT). This study shows that this interregulation is due to competition between progeny of these 2 pathways because depletion of thymic progeny leads to increased peripheral expansion in thymus-bearing hosts. To test the hypothesis that competition for growth factors modulates the magnitude of antigen-driven peripheral expansion during immune reconstitution in vivo, a variety of T. cell active cytokines were administered after BMT. Of the cytokines (interleukins) tested (IL-3, IL-12, IL-6, IL-2, and IL-7), IL-2 modestly increased peripheral expansion in the face of increasing numbers of thymic emigrants, whereas IL-7 potently accomplished this. This report also demonstrates that the beneficial effect of IL-7 on immune reconstitution is related to both increases in thymopoiesis as well as a direct increase in the magnitude of antigen-driven peripheral expansion. Therefore, the administration of exogenous IL-7, and to a lesser extent IL-2, abrogates the down-regulation in antigen-driven peripheral expansion that occurs in thymus-bearing hosts after BMT. These results suggest that one mechanism by which T. cell-depleted hosts may support antigen-driven T-cell expansion in vivo is via an increased availability of T-cell-active cytokines to support clonal expansion.

Original languageEnglish (US)
Pages (from-to)1491-1497
Number of pages7
Issue number5
StatePublished - Mar 1 2001
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology


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