Forming a Complex with MHC Class I Molecules Interferes with Mouse CD1d Functional Expression

Renukaradhya J Gourapura,Masood A Khan,Jianyun Liu,Randy R Brutkiewicz,Daniel Shaji,Richard M Gallo,Johan K Sandberg

doi:10.1371/journal.pone.0072867

Renukaradhya J Gourapura, Masood A Khan + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0072867

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Abstract

CD1d molecules are structurally similar to MHC class I, but present lipid antigens as opposed to peptides. Here, we show that MHC class I molecules physically associate with (and regulate the functional expression of) mouse CD1d on the surface of cells. Low pH (3.0) acid stripping of MHC class I molecules resulted in increased surface expression of murine CD1d on antigen presenting cells as well as augmented CD1d-mediated antigen presentation to NKT cells. Consistent with the above results, TAP1-/- mice were found to have a higher percentage of type I NKT cells as compared to wild type mice. Moreover, bone marrow-derived dendritic cells from TAP1-/- mice showed increased antigen presentation by CD1d compared to wild type mice. Together, these results suggest that MHC class I molecules can regulate NKT cell function, in part, by masking CD1d.

Highlights

CD1d constitutes a third antigen (Ag) presenting pathway to contrast with those mediated by major histocompatibility complex (MHC) class I and MHC class II molecules [1,2]
To analyze the role of MHC class I molecules in the regulation of the functional expression of CD1d in antigen presenting cells (APCs), we stripped off cell surface MHC class I molecules using low pH citric acid buffer [32]
Cells expressing exogenous mouse CD1d were treated with citric acid buffer for increasing amounts of time, and CD1d-mediated Ag presentation was analyzed by co-culturing the cells with NKT cell hybridomas

Summary

Introduction

CD1d constitutes a third antigen (Ag) presenting pathway to contrast with those mediated by major histocompatibility complex (MHC) class I and MHC class II molecules [1,2]. 5 μg/ml of anti-CD1d mAb (1H6), the anti-MHC class I mAb TIB126 or isotype control mAbs were added to mock- or citric acid-treated LMTK-CD1d1 or LMTK-control cells for 1 h on ice. The cells were washed and co-cultured with the NKT cell hybridomas as described above. Cells expressing exogenous mouse CD1d were treated with citric acid buffer for increasing amounts of time, and CD1d-mediated Ag presentation was analyzed by co-culturing the cells with NKT cell hybridomas.

Results

Conclusion