Cross-dressing: an alternative mechanism for antigen presentation.

Cross-dressing involves the transfer of preformed functional peptide-MHC complexes from the surface of donor cells to recipient cells, such as dendritic cells (DCs). These cross-dressed cells might eventually present the intact, unprocessed peptide-MHC complexes to T lymphocytes. In this review we will discuss some recent findings concerning the intercellular transfer of preformed MHC complexes and the possible mechanisms by which the transfer may occur. We will report evidences showing that both MHC class I and MHC class II functional complexes might be transferred, highlighting the physiological relevance of these cross-dressed cells for the presentation of exogenous antigens to both cytotoxic and helper T lymphocytes.