Abstracts (complete list) - Wissenschaft Online

Sven Burgdorf, Christian Kurts
Current models and mechanisms of antigen crosspresentation
After internalization and processing of extracellular antigens, dendritic cells can induce
an adaptive immune response by presenting antigenic epitopes on both MHC II
molecules (to activate CD4+ T helper cells) and MHC I molecules (to activate CD8+
cytotoxic T killer cells). The latter process has been termed cross-presentation.
Increasing evidence supports an important role of cross-presentation in various
biological processes. Nevertheless, the molecular mechanisms regulating intracellular
processing of internalized antigens and loading of the derived peptides on MHC class I
molecules remain largely unknown.
At present, several models have been proposed to explain how endocytosed antigens
might reach the MHC I presentation pathway. Most of them point out a decisive role of
the ER associated degradation machinery (ERAD) and the cytoplasmic proteasome. Our
recent findings support a further mechanism in which distinct endocytosis mechanisms
selectively introduce soluble antigens into an organelle dedicated to cross-presentation
and distinct from classical lysosomes. In this presentation, I will review the current cellbiological
models of cross-presentation, focussing on their similarities and distinctions
and on the unanswered questions pertaining to its molecular regulation.