HIV-1 binding to CD4 on CD4+CD25+ regulatory T cells enhances their suppressive function and induces them to home to, and accumulate in, peripheral and mucosal lymphoid tissues: an additional mechanism of immunosuppression

Int Immunol. 2009 Mar;21(3):283-94. doi: 10.1093/intimm/dxn146. Epub 2009 Feb 10.


The establishment and persistence of many chronic infections have been demonstrated to depend on restraint of the vigor of the anti-microbial immune responses by CD4+CD25+ regulatory T (Treg) cells. In HIV-infected individuals, Treg cells suppress both HIV-specific and general CD4+ and CD8+ T cell responses. Increases of CD4+CD25+ Treg cell function during viral infections might be mediated by host-derived pro-inflammatory molecules or directly by viral infection or binding. We examined the effect HIV has upon binding to CD4+CD25+ Treg cells by exposing human purified CD4+CD25+ T cells from healthy donors to HIV-1 in vitro and assessing their Treg-associated functional marker profile and suppressive activities. We found that HIV-1 binding increased their suppressor activities by 2- to 5-fold, which was accompanied by enhanced expression of Treg-associated functional markers sCTLA-4, glucocorticoid-induced tumor necrosis factor receptor and FoxP3. Moreover, HIV-1 binding extended the survival of CD4+CD25+ Treg cells and up-regulated the expression of homing receptors CD62L and integrin alpha4beta7, which in turn would result in Treg cells migrating more rapidly to the peripheral lymph nodes and mucosal lymphoid tissues where anti-HIV immune responses are occurring. Importantly, CD4+CD25+ Treg cells exposed to HIV were not susceptible to homing-induced apoptosis like are other resting CD4+ cells following HIV-1 binding. We show that CD4+CD25+ Treg cells respond directly to HIV-1 itself through HIV gp120 interactions with CD4 molecules. Collectively, our findings explain a mechanism that contributes to the abnormal accumulation of intensified Treg cells in lymphoid and mucosal tissues in HIV patients, resulting in impairment of immune responses which would greatly help HIV persistence.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antigens, CD / genetics
  • Antigens, CD / immunology
  • Antigens, CD / metabolism
  • Apoptosis / immunology
  • CD4 Antigens / immunology
  • CD4 Antigens / metabolism*
  • CTLA-4 Antigen
  • Cell Differentiation
  • Cell Movement
  • Female
  • Forkhead Transcription Factors / genetics
  • Forkhead Transcription Factors / immunology
  • Forkhead Transcription Factors / metabolism
  • Glucocorticoid-Induced TNFR-Related Protein
  • HIV Envelope Protein gp120 / immunology
  • HIV Envelope Protein gp120 / metabolism
  • HIV Infections / immunology*
  • HIV-1 / immunology*
  • Humans
  • Immune Tolerance*
  • Integrins / genetics
  • Integrins / immunology
  • Integrins / metabolism
  • L-Selectin / genetics
  • L-Selectin / immunology
  • L-Selectin / metabolism
  • Lymph Nodes / immunology
  • Lymph Nodes / pathology
  • Mice
  • Mice, SCID
  • Mucous Membrane / immunology
  • Mucous Membrane / pathology
  • Protein Binding
  • Receptors, Nerve Growth Factor / genetics
  • Receptors, Nerve Growth Factor / immunology
  • Receptors, Nerve Growth Factor / metabolism
  • Receptors, Tumor Necrosis Factor / genetics
  • Receptors, Tumor Necrosis Factor / immunology
  • Receptors, Tumor Necrosis Factor / metabolism
  • T-Lymphocytes, Regulatory / immunology
  • T-Lymphocytes, Regulatory / metabolism*
  • T-Lymphocytes, Regulatory / pathology


  • Antigens, CD
  • CD4 Antigens
  • CTLA-4 Antigen
  • CTLA4 protein, human
  • Ctla4 protein, mouse
  • Forkhead Transcription Factors
  • Foxp3 protein, mouse
  • Glucocorticoid-Induced TNFR-Related Protein
  • HIV Envelope Protein gp120
  • Integrins
  • Receptors, Nerve Growth Factor
  • Receptors, Tumor Necrosis Factor
  • Tnfrsf18 protein, mouse
  • integrin alpha4beta7
  • L-Selectin