Structural analysis of anti-DR1 allorecognition by using DR1/H-2Ek hybrid molecules. Influence of the beta 2-domain correlates with CD4 dependence.
A segmental analysis of the key regions of HLA-DR1 that control T cell allorecognition was performed by using a series of transfected cell lines expressing the products of recombinant DRB/H-2Eb genes, paired with either DR alpha or H-2E alpha. Four of eight human T cell clones tolerated substitution of the H-2E alpha chain, but only one clone showed any response to the DR alpha/H-2E beta k dimer. Both the membrane-proximal and the membrane-distal domains of the beta-chain played an important part in stimulating these clones. The response of four of eight clones was markedly inhibited by substitution of the H-2E beta 2 for the DR beta 2 domain. This inhibition showed a complete correlation with the sensitivity of the clones to inhibition by anti-CD4 mAb. Taken together, these results suggest that the interaction site for CD4 may include residues on the beta 2-domain. Introduction of H-2Ek sequence into either half of the beta 1-domain led to a complete loss of response by all but two of the clones. This is consistent with these clones having dual specificity for exposed DR1-specific polymorphisms and for DR1-bound peptides. The pattern of response of one of the clones suggested that indirect conformational effects on the alpha 1-domain may also contribute to the influence of the amino-terminal half of the beta 1-domain on T cell recognition. In the presence of H-2E alpha, this clone responded more strongly when the amino-terminal half of the beta 1-domain was of H-2Ek rather than DR1 sequence. This implies that species matching of the floor of the beta 1-domain with the alpha-chain is more important than the presence of the alpha-chain of the parental species.
Lombardi
G
G
Department of Immunology, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Barber
L
L
Aichinger
G
G
Heaton
T
T
Sidhu
S
S
Batchelor
J R
JR
Lechler
R I
RI
D000595:Amino Acid Sequence; D001665:Binding Sites; D015704:CD4 Antigens / Q000502:physiology*; D002999:Clone Cells; D003001:Cloning, Molecular; D000939:Epitopes; D006183:H-2 Antigens / Q000276:immunology; D015798:HLA-DR1 Antigen / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D006801:Humans; D066298:In Vitro Techniques; D008285:Major Histocompatibility Complex; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011993:Recombinant Fusion Proteins; D013329:Structure-Activity Relationship; D013601:T-Lymphocytes / Q000276:immunology*; D014162:Transfection
D015704:CD4 Antigens; D000939:Epitopes; D006183:H-2 Antigens; D015798:HLA-DR1 Antigen; D011993:Recombinant Fusion Proteins