GLYCAN-REGULATED ANTIGEN-PROCESSING OF A PROTEIN IN THE ENDOPLASMIC-RETICULUM CAN UNCOVER CRYPTIC CYTOTOXIC T-CELL EPITOPES

We and others have shown that influenza A nucleoprotein (NP) targeted to the secretory pathway cannot be processed to yield several cytotoxi c T lymphocyte (CTL) epitopes in cell lines that lack the transporter associated with antigen processing (TAP). However, a large COOH-termin al fragment of NP is processed and presented in these cells. Full-leng th NP is cotranslationally glycosylated in the lumen of the endoplasmi c reticulum at two sites distal to the major H2-K-k and H2-D-b restric ted CTL epitopes, and we show here that pharmacological or genetic inh ibition of N-linked glycosylation, leads to the processing and present ation of both these epitopes in a TAP-independent way.