Related Experiment Videos
[Antigen presentation and macrophages]
1INSERM U.396, Laboratoire d'Immunologie et d'Histocompatibilité, Hôpital Saint-Louis, Paris, France.
T-cells recognize antigenic peptides associated with HLA molecules belonging to Class I (HLA-A, -B, or -C) or Class II (HLA-DP, -DQ, -DR). Roughly, Class I HLA molecules represent antigens to cytotoxic CD8+ T-cells and Class II HLA molecules to helper CD4+ T-cells. Class II HLA molecules primarily present "exogenic" peptides that penetrate within cells by endocytosis, whereas Class I HLA molecules present "endogenic" peptides produced within cells. In both cases, the mechanisms of antigen presentation are closely liked to the biosynthesis of HLA molecules and to the expression of other molecules including proteasome (LMP) and the peptide transporters (TAP) needed to transport peptides through the endoplasmic reticulum in the case of Class I molecules, and invariant chain (Ii) and HLA-DM antigens in the case of Class II molecules. In addition, "exogenous" presentation by Class I molecules has recently been described, and may be relatively specific of phagocytic cells such as macrophages.
T-cells recognize antigenic peptides associated with HLA molecules belonging to Class I (HLA-A, -B, or -C) or Class II (HLA-DP, -DQ, -DR). Roughly, Class I HLA molecules represent antigens to cytotoxic CD8+ T-cells and Class II HLA molecules to helper CD4+ T-cells. Class II HLA molecules primarily present "exogenic" peptides that penetrate within cells by endocytosis, whereas Class I HLA molecules present "endogenic" peptides produced within cells. In both cases, the mechanisms of antigen presentation are closely liked to the biosynthesis of HLA molecules and to the expression of other molecules including proteasome (LMP) and the peptide transporters (TAP) needed to transport peptides through the endoplasmic reticulum in the case of Class I molecules, and invariant chain (Ii) and HLA-DM antigens in the case of Class II molecules. In addition, "exogenous" presentation by Class I molecules has recently been described, and may be relatively specific of phagocytic cells such as macrophages.