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 language||English (US)|
|Number of pages||10|
|Journal||Journal of Immunology|
|State||Published - Jul 1 2003|
ASJC Scopus subject areas
- Immunology and Allergy