Information sharing and collateral damage

Recent studies have revealed a novel mechanism of antigen cross-presentation by intercellular peptide transfer through gap junctions, which provides new insight about how the immune system recognizes and destroys viruses and tumor cells. At the site of infection or tumorigenesis, gap junctions provide an ' information-sharing ' channel through which viral- and tumor-derived peptides; are transferred to professional antigen-presenting cells (APCs), leading to naive T-cell stimulation. Similarly, gap-junction-mediated peptide transfer from infected or malignant cells to neighboring cells incurs ' collateral damage ' by cytotoxic T cells, thereby limiting the spread of viruses or the progression of tumors.