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The Ia.2 epitope defines a subset of lipid raft-resident MHC class II molecules crucial to effective antigen presentation.
- Source :
-
Journal of immunology (Baltimore, Md. : 1950) [J Immunol] 2011 Jun 15; Vol. 186 (12), pp. 6710-7. Date of Electronic Publication: 2011 May 04. - Publication Year :
- 2011
-
Abstract
- Previous work established that binding of the 11-5.2 anti-I-A(k) mAb, which recognizes the Ia.2 epitope on I-A(k) class II molecules, elicits MHC class II signaling, whereas binding of two other anti-I-A(k) mAbs that recognize the Ia.17 epitope fail to elicit signaling. Using a biochemical approach, we establish that the Ia.2 epitope recognized by the widely used 11-5.2 mAb defines a subset of cell surface I-A(k) molecules predominantly found within membrane lipid rafts. Functional studies demonstrate that the Ia.2-bearing subset of I-A(k) class II molecules is critically necessary for effective B cell-T cell interactions, especially at low Ag doses, a finding consistent with published studies on the role of raft-resident class II molecules in CD4 T cell activation. Interestingly, B cells expressing recombinant I-A(k) class II molecules possessing a β-chain-tethered hen egg lysosome peptide lack the Ia.2 epitope and fail to partition into lipid rafts. Moreover, cells expressing Ia.2(-) tethered peptide-class II molecules are severely impaired in their ability to present both tethered peptide or peptide derived from exogenous Ag to CD4 T cells. These results establish the Ia.2 epitope as defining a lipid raft-resident MHC class II conformer vital to the initiation of MHC class II-restricted B cell-T cell interactions.
Details
- Language :
- English
- ISSN :
- 1550-6606
- Volume :
- 186
- Issue :
- 12
- Database :
- MEDLINE
- Journal :
- Journal of immunology (Baltimore, Md. : 1950)
- Publication Type :
- Academic Journal
- Accession number :
- 21543648
- Full Text :
- https://doi.org/10.4049/jimmunol.1100336