Glycosylphosphatidylinositol-anchored H-2D(b) molecules are defective in antigen processing and presentation to cytotoxic T lymphocytes

Glycosylphosphatidylinositol-anchored (GPI)-D-b molecules are defective in mediating cytotoxic T lymphocytes (CTL) lysis of transfected lymphoma cells, compared to their transmembrane (TM) counterpart. This defect is manifest when antigenic peptide must be processed and presented through the endogenous pathway. These same transfectants can be lysed by allospecific CTL, or by antigen-specific D-b-restricted CTL when pulsed with appropriate exogenous synthetic peptide, demonstrating that they can bind and present peptide for CTL-mediated lympholysis. The defect apparently results from differences between GPI-D-b and TM-D-b assembly and transport, or from differences in membrane topology that affect CD8+ Cn recognition of major histocompatibility complex/peptide complex.