Mycobacterium tuberculosis LprG (Rv1411c): A Novel TLR-2 Ligand That Inhibits Human Macrophage Class II MHC Antigen Processing

摘要

MHC class II (MHC-II)-restricted CD4+ T cells are essential for control of Mycobacterium tuberculosis infection. This report describes the identification and purification of LprG ( Rv1411c ) as an inhibitor of primary human macrophage MHC-II Ag processing. LprG is a 24-kDa lipoprotein found in the M. tuberculosis cell wall. Prolonged exposure (16 h) of human macrophages to LprG resulted in marked inhibition of MHC-II Ag processing. Inhibition of MHC-II Ag processing was dependent on TLR-2. Short-term exposure (6 h) to LprG stimulated TLR-2-dependent TNF-α production. Thus, LprG can exploit TLR-2 signaling to inhibit MHC-II Ag processing in human macrophages. Inhibition of MHC-II Ag processing by mycobacterial lipoproteins may allow M. tuberculosis , within infected macrophages, to avoid recognition by CD4+ T cells.