Activated human T lymphocytes express MHC class I heavy chains not associated with beta 2-microglobulin.
We present here the molecular characterization of a new activation-induced surface structure on human T lymphocytes, termed LA45, with high homology (93% at protein level) to MHC class I molecules. Antigen modulation and sequential immunoprecipitation experiments revealed that LA45 and HLA class I proteins do not crossreact with the corresponding antibodies. Furthermore, LA45 is not associated with beta 2-m. On the other hand, we could show that the separation of HLA-A,B,C and beta 2m molecules, induced by SDS-denaturation, leads to a conformational change in the heavy chain in such a way that it becomes reactive with LA45. The 90/45 kD LA45 proteins thus appear to be non-beta 2m-associated MHC class I alpha chains that are selectively expressed by activated but not by resting human T lymphocytes.
Schnabl
E
E
Institute of Immunology, Vienna, Austria.
Stockinger
H
H
Majdic
O
O
Gaugitsch
H
H
Lindley
I J
IJ
Maurer
D
D
Hajek-Rosenmayr
A
A
Knapp
W
W
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000032:analysis*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D001483:Base Sequence; D015153:Blotting, Western; D017252:CD3 Complex; D002478:Cells, Cultured; D003001:Cloning, Molecular; D015395:Histocompatibility Antigens Class I / Q000032:analysis* / Q000235:genetics; D006801:Humans; D008213:Lymphocyte Activation; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D011948:Receptors, Antigen, T-Cell / Q000032:analysis; D012689:Sequence Homology, Nucleic Acid; D013601:T-Lymphocytes / Q000276:immunology*; D001613:beta 2-Microglobulin / Q000032:analysis*
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D015395:Histocompatibility Antigens Class I; C063959:LA45 antigen; D046911:Macromolecular Substances; D011948:Receptors, Antigen, T-Cell; D001613:beta 2-Microglobulin