The origin and fate of beta 2m-free MHC class I molecules induced on activated T cells.
We report here that the expression of major histocompatibility complex (MHC) class I heavy chains not associated with beta 2-microglobulin is induced on resting human T cells by a variety of stimuli. These beta 2m-free class I heavy chains are not transported as such from the endoplasmic reticulum but originate from surface beta 2m-associated MHC class I molecules. beta 2m-free class I heavy chains are spontaneously released from the surface of activated cells. Cross-linking of beta 2m-free class I heavy chains with specific monoclonal antibodies results in the rapid down-regulation and internalization of these molecules. In contrast, beta 2m-associated MHC class I molecules display a different pattern of modulation. Previously, we reported that beta 2m-free class I heavy chains interact with CD8 molecules expressed on the same activated T cells. We propose that interactions between these molecules are involved in a mechanism regulating the function of activated T cells.
Demaria
S
S
Laboratory of Molecular Immunology, Public Health Research Institute, New York, New York 10016.
Schwab
R
R
Bushkin
Y
Y
D020126:Brefeldin A; D002462:Cell Membrane / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D003517:Cyclopentanes / Q000494:pharmacology; D015395:Histocompatibility Antigens Class I / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000737:chemistry / Q000378:metabolism*; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000737:chemistry / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D001613:beta 2-Microglobulin / Q000378:metabolism*
D003470:Culture Media; D003517:Cyclopentanes; D015395:Histocompatibility Antigens Class I; D007143:Immunoglobulin Heavy Chains; D001613:beta 2-Microglobulin; D020126:Brefeldin A; D013755:Tetradecanoylphorbol Acetate