The role of the endoplasmic reticulum in antigen processing. N-glycosylation of influenza hemagglutinin abrogates CD4+ cytotoxic T cell recognition of endogenously processed antigen.
Evidence is presented for an endogenous route of Ag processing for CD4+ T cell recognition of influenza hemagglutinin that requires obligatory traffic of de novo synthesized hemagglutinin across the lumen of the endoplasmic reticulum for processing in a cytosolic compartment. I-Ad-restricted T cell clones that recognize synthetic peptides corresponding to two distinct antigenic regions of the HA1 subunit, HA1 56-76 and HA1 177-199, are cytotoxic and, dependent on epitope specificity can recognize endogenously processed Ag and lyse class II+ target cells infected with a recombinant vaccinia-X31 HA virus. HA1 56-76 specific T cell clones fail to recognize (target cells infected with) influenza X31 viruses, containing a single residue change, HA1 63 Asp----Asn that introduces an oligosaccharide attachment site: Asp63Cys64Thr65. Recognition is restored, however, by tunicamycin treatment of mutant virus infected target cells. Inasmuch as N-glycosylation of nascent hemagglutinin polypeptides occurs in the lumen of the endoplasmic reticulum, this indicates a route of endogenous processing for hemagglutinin, requiring transport across the endoplasmic reticulum, which has been confirmed by the failure of CD4+ T cells to recognize a recombinant VACC-hemagglutinin virus in which the same single residue change, HA1 63 Asp----Asn has been introduced by site directed mutagenesis.
National Institute for Medical Research, Mill Hill, London, U.K.
D B
DB
Thomas
J
J
Hodgson
P F
PF
Riska
C M
CM
Graham
D000595:Amino Acid Sequence; D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D000956:Antigens, Viral / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002738:Chloroquine / Q000494:pharmacology; D003602:Cytotoxicity, Immunologic; D004721:Endoplasmic Reticulum / Q000502:physiology*; D000939:Epitopes; D006023:Glycoproteins / Q000276:immunology; D006031:Glycosylation; D006389:Hemagglutinins, Viral / Q000276:immunology* / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D009980:Influenza A virus / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D000956:Antigens, Viral; D000939:Epitopes; D006023:Glycoproteins; D006389:Hemagglutinins, Viral; D000949:Histocompatibility Antigens Class II; D000643:Ammonium Chloride; D002738:Chloroquine