GLYCOSYLPHOSPHATIDYLINOSITOL-ANCHORED H-2D(B) MOLECULES ARE DEFECTIVEIN ANTIGEN-PROCESSING AND PRESENTATION TO CYTOTOXIC T-LYMPHOCYTES

Glycosylphosphatidylinositol-anchored (GPI)-D-b molecules are defectiv e in mediating cytotoxic T lymphocytes (CTL) lysis of transfected lymp homa cells, compared to their transmembrane (TM) counterpart. This def ect 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 p ulsed with appropriate exogenous synthetic peptide, demonstrating that they can bind and present peptide for CTL-mediated lympholysis. The d efect apparently results from differences between GPI-D-b and TM-D-b a ssembly and transport, or from differences in membrane topology that a ffect CD8+ Cn recognition of major histocompatibility complex/peptide complex.