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The Ia.2 Epitope Defines a Subset of Lipid Raft-Resident MHC Class II Molecules Crucial to Effective Antigen Presentation

The Ia.2 Epitope Defines a Subset of Lipid Raft-Resident MHC Class II Molecules Crucial to Effective Antigen Presentation
The Ia.2 Epitope Defines a Subset of Lipid Raft-Resident MHC Class II Molecules Crucial to Effective Antigen Presentation
Previous work established that binding of the 11-5.2 anti–I-Ak mAb, which recognizes the Ia.2 epitope on I-Ak class II molecules, elicits MHC class II signaling, whereas binding of two other anti–I-Ak 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-Ak molecules predominantly found within membrane lipid rafts. Functional studies demonstrate that the Ia.2-bearing subset of I-Ak 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-Ak class II molecules possessing a b-chain–tethered hen egg lysosome peptide lack the Ia.2 epitope and fail to partition into lipid rafts. Moreover, cells expressing Ia.22 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.
0022-1767
6710-6717
Busman-Sahay, Kathleen
5a0edadc-0c7b-412c-a98f-342027b93799
Sargent, Elizabeth
1a3b24fb-01bb-4452-9bb4-776438bf3cf0
Harton, Jonathan A.
31734550-3ac9-4655-b1f3-703023863cc4
Drake, James R.
2482577b-8d3a-4aae-af65-e4f676a2e468
Busman-Sahay, Kathleen
5a0edadc-0c7b-412c-a98f-342027b93799
Sargent, Elizabeth
1a3b24fb-01bb-4452-9bb4-776438bf3cf0
Harton, Jonathan A.
31734550-3ac9-4655-b1f3-703023863cc4
Drake, James R.
2482577b-8d3a-4aae-af65-e4f676a2e468

Busman-Sahay, Kathleen, Sargent, Elizabeth, Harton, Jonathan A. and Drake, James R. (2011) The Ia.2 Epitope Defines a Subset of Lipid Raft-Resident MHC Class II Molecules Crucial to Effective Antigen Presentation. Journal of Immunology, 186 (12), 6710-6717. (doi:10.4049/jimmunol.1100336).

Record type: Article

Abstract

Previous work established that binding of the 11-5.2 anti–I-Ak mAb, which recognizes the Ia.2 epitope on I-Ak class II molecules, elicits MHC class II signaling, whereas binding of two other anti–I-Ak 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-Ak molecules predominantly found within membrane lipid rafts. Functional studies demonstrate that the Ia.2-bearing subset of I-Ak 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-Ak class II molecules possessing a b-chain–tethered hen egg lysosome peptide lack the Ia.2 epitope and fail to partition into lipid rafts. Moreover, cells expressing Ia.22 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.

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Published date: 15 June 2011
Organisations: Ocean Biochemistry & Ecosystems

Identifiers

Local EPrints ID: 190253
URI: https://eprints.soton.ac.uk/id/eprint/190253
ISSN: 0022-1767
PURE UUID: f9a4a17c-fa94-422b-a26c-cdb318c9127c

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Date deposited: 10 Jun 2011 12:29
Last modified: 18 Jul 2017 11:39

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Contributors

Author: Kathleen Busman-Sahay
Author: Elizabeth Sargent
Author: Jonathan A. Harton
Author: James R. Drake

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