cell lines not expressing MHC class I molecules
luscher at immune.med.utoronto.ca
Wed Aug 23 15:08:02 EST 1995
>In article <dtyyu.10.00146E5E at ucla.edu>, dtyyu at ucla.edu (David Tak Yan Yu)
>> Has any one generated any cell line not expressing MHC class I eg
>because of a
>> defect in the B2m expression. We would be very interested to use in
>> David Yu,
R1E is such a cell line (murine origin). There exist transfectants of the B2m- cell line with the Db and Kb heavy chains, with and without the intact b2m gene. See:
Allen, H., J. Fraser, D. Flyer, S. Calvin, and R. Flavell. 1986. b2-microglobulin is not required for cell surface expression of the murine class I histocompatibility antigen H-2Db or of a truncated H-2Db. Proc. Natl. Acad. Sci. USA 83:7447-7451.
beta 2-Microglobulin (beta 2m) has been thought essential for transport of all major histocompatibility complex class I antigens to the cell surface. Here, we show that the mouse class I antigen H-2Db is expressed at the cell surface even when there is no beta 2m present within the cell. This was established by transfecting the H-2Db gene into the R1E cell line, which lacks beta 2m. The conformation of the Db antigen expressed by the R1E transfectant is very different from that of the native molecule. This Db antigen is not recognized by Db-allospecific and Db-restricted cytotoxic T lymphocytes or by most monoclonal antibodies to the native Db. We show further that a deletion construct of the Db gene, which consists of exon 1 linked to exons 4-8, expresses a truncated Db antigen lacking domains 1 and 2 [Db-(1 + 2)] at the cell surface after transfection into the R1E line. Previous biochemical and crystallographic data have indicated that domain 3 is associated with beta 2m; unexpectedly, Db-(1 + 2) does not associate with beta 2m when the mouse beta 2mb gene is transfected into the R1E transfectant expressing the truncated Db. This suggests that interactions with domains 1 and 2 are important for the paired association of domain 3 and beta 2m in the native Db antigen.
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