Inducible MHC class II expression by mast cells supports effector and regulatory T cell activation1

• Published in: The Journal of immunology (1950) Vol. 182; no. 8; pp. 4686 - 4695
• Main Authors: Kambayashi, Taku, Allenspach, Eric J., Chang, John T., Zou, Tao, Shoag, Jonathan E., Reiner, Steven L., Caton, Andrew J., Koretzky, Gary A.
• Format: Journal Article
• Language: English
• Published: 15.04.2009
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.0803180

In addition to their well-established role as regulators of allergic response, recent evidence supports a role for mast cells in influencing the outcome of physiologic and pathologic T cell responses. One mechanism by which mast cells influence T cell function is indirectly through secretion of various cytokines. It remains unclear, however, whether mast cells can directly activate T cells through antigen presentation, as the expression of MHC class II by mast cells has been controversial. In this report, we demonstrate that in vitro stimulation of mouse mast cells with LPS and IFNγ induces the expression of MHC class II and co-stimulatory molecules. Although freshly isolated peritoneal mast cells do not express MHC class II, an in vivo inflammatory stimulus increases numbers of MHC class II-positive mast cells in situ. Expression of MHC class II granted mast cells the ability to process and present antigens directly to T cells with preferential expansion of antigen-specific regulatory T cells over naive T cells. These data support the notion that, in the appropriate setting, mast cells may regulate T cell responses through the direct presentation of antigen.