Inhibition of IFN-γ-induced class II transactivator expression by a 19-kDa lipoprotein from Mycobacterium tuberculosis: A potential mechanism for immune evasion

Rish K. Pai, Marilyn Convery, Thomas A. Hamilton, W. Henry Boom, Clifford V. Harding

Research output: Contribution to journalArticlepeer-review

202 Scopus citations

Abstract

Mycobacterium tuberculosis (MTB) persists inside macrophages despite vigorous immune responses. MTB and MTB 19-kDa lipoprotein inhibit class II MHC (MHC-II) expression and Ag processing by a Toll-like receptor 2-dependent mechanism that is shown in this study to involve a defect in IFN-γ induction of class II transactivator (CIITA). Exposure of macrophages to MTB or MTB 19-kDa lipoprotein inhibited IFN-γ-induced MHC-II expression, but not IL-4-induced MHC-II expression, by preventing induction of mRNA for CIITA (total, type I, and type IV), IFN regulatory factor-1, and MHC-II. MTB 19-kDa lipoprotein induced mRNA for suppressor of cytokine signaling (SOCS)1 but did not inhibit IFN-γ-induced Stat1 phosphorylation. Furthermore, the lipoprotein inhibited MHC-II Ag processing in SOCS1-/- macrophages. MTB 19-kDa lipoprotein did not inhibit translocation of phosphorylated Stat1 to the nucleus or Statl binding to and transactivation of IFN-γ-sensitive promoter constructs. Thus, MTB 19-kDa lipoprotein inhibited IFN-γ signaling independent of SOCS1 and without interfering with the activation of Stat1. Inhi-bition of IFN-γ-induced CIITA by MTB 19-kDa lipoprotein may allow MTB to evade detection by CD4+ T cells.

Original languageEnglish (US)
Pages (from-to)175-184
Number of pages10
JournalJournal of Immunology
Volume171
Issue number1
StatePublished - Jul 1 2003

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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