Dissociation of β 2-microglobulin is responsible for selective reduction of HLA class I antigenicity following acid treatment of cells

Abstract

β 2-Microglobulin (β 2m) dissociated from surface HLA class I complex following exposure of cells to low pH and was detected in supernatant by radioimmunoprecipitation with specific monoclonal antibodies (mAbs). As the concn of β 2m in supernatant increased, the binding of mAbs, specific for HLA class I heavy chains associated with β 2m, to the cell surface declined. Binding of mAb specific for free HLA class I heavy chain to the cell surface increased after acid treatment. Reassociation with exogenous β 2m confirmed increase in the number of free HLA class I heavy chains on surface of the cells after their exposure to low pH and also at least partially restored the reactivity with mAbs specific to HLA class I heavy chains associated with β 2m. Dissociation of β 2m from GD1 complex following acid treatment was also accompanied with the changes in antigenicity of cell surface CD1 molecules.