MHC class II deletion mutant expresses normal levels of transgene encoded class II molecules that have abnormal conformation and impaired antigen presentation ability.
Successive transfers of HLA-DR alpha and beta genes restored expression of HLA-DR antigens to human B-lymphoblastoid cell line, LCL .174, from which all known expressible class II genes are deleted. While transferent cells displayed large amounts of DR on their surfaces, transgene-encoded DR3 molecules lacked a conformation-dependent epitope. DR1-restricted CTL lysis of DR1-expressing transferents pulsed with native influenza virus proteins was greatly reduced; the same cells were efficiently lysed in the presence of CTL-recognized influenza peptides. The properties of DR-expressing transferents of .174 suggest they are defective in producing peptides from exogenous proteins or in forming DR/peptide complexes. Comparison with other DR-expressing deletion mutants indicates that at least one gene in an approximately 230 kb DNA segment between the DQ1 and Ring 7 loci is needed for normal DR-mediated processing and presentation. Production of DR3 molecules having the conformation-dependent 16.23 epitope and efficient DR1-restricted presentation of influenza viral epitopes occurred in a B cell line that has a mutation specifically eliminating expression of the TAP1 transporter gene, which is in the approximately 230 kb interval and is needed for production of HLA class I/peptide complexes.
Ceman
S
S
Department of Genetics, University of Wisconsin, Madison 53706.
Rudersdorf
R
R
Long
E O
EO
Demars
R
R
D000911:Antibodies, Monoclonal / Q000276:immunology; D000938:Antigen-Presenting Cells / Q000276:immunology; D002352:Carrier Proteins / Q000235:genetics; D002872:Chromosome Deletion; D005802:Genes, MHC Class II; D006684:HLA-DR Antigens / Q000235:genetics* / Q000648:ultrastructure; D006801:Humans; D066298:In Vitro Techniques; D008285:Major Histocompatibility Complex; D009154:Mutation; D011487:Protein Conformation; D014162:Transfection
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D006684:HLA-DR Antigens