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M9650195.TXT
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1996-03-09
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Document 0195
DOCN M9650195
TI Definition of sites on HLA-DR1 involved in the T cell response to
staphylococcal enterotoxins E and C2.
DT 9605
AU Hargreaves RE; Brehm RD; Tranter H; Warrens AN; Lombardi G; Lechler RI;
Department of Immunology, Royal Postgraduate Medical School,;
Hammersmith Hospital, London, GB.
SO Eur J Immunol. 1995 Dec;25(12):3437-44. Unique Identifier : AIDSLINE
MED/96140684
AB We have exploited the relative inefficiency of interaction between
staphylococcal enterotoxins, SEE or SEC2, and H-2Ek compared to HLA-DR1
molecules to deduce which regions of the major histocompatibility
complex (MHC) class II molecule are involved in the T cell response to
these superantigens. Transfectants expressing hybrid DR/H-2E MHC class
II molecules were used to present SEE to the T cell receptor V beta
8.1-expressing Jurkat cell line, and SEC2 to human peripheral blood T
cells. For SEE, the critical region of the class II molecule for T cell
reactivity and for binding was the beta 1 domain alpha-helix. The
functional data were corroborated by measurements of direct binding.
Sequence comparison between DR and H-2E raised the possibility that the
glutamic acid at position 84 in the beta chain of H-2Ek, in place of
glycine was responsible for the observed functional effects. This
suggestion was supported by the finding that DQw2 (glutamine at 84)
transfectants supported the SEE response much more efficiently than DQw6
that has glutamic acid at this position. In addition, amino acid
substitutions at either position 36 or 39 in the DR alpha 1 domain
abolished T cell reactivity without any obvious alteration in binding.
For SEC2, use of transfectants expressing exon-shuffled alpha and beta
chain genes showed that replacement of the alpha 1, alpha 2 and beta 1
domains with H-2E sequence inhibited the presentation of SEC2.
Similarly, the substitutions at positions 36 and 39 in the alpha 1
domain abolished the T cell response to SEC2. Taken together, these data
may be best explained by a model in which these two toxins have primary
binding sites on the beta 1 domain (SEE) and the alpha 1 and alpha 2
domains (SEC2), but by virtue of a secondary binding site on the
opposite surface of the class II molecule, cross-link two adjacent DR
molecules. Such cross-linking may be important in the induction of T
cell reactivity.
DE Amino Acid Sequence Antigen Presentation Clone Cells CD4-Positive
T-Lymphocytes/IMMUNOLOGY CD8-Positive T-Lymphocytes/IMMUNOLOGY
Enterotoxins/*IMMUNOLOGY H-2 Antigens/IMMUNOLOGY Human HLA-DR1
Antigen/CHEMISTRY/GENETICS/*IMMUNOLOGY Lymphocyte Transformation
Molecular Sequence Data Protein Binding Protein Conformation
Staphylococcus aureus/*IMMUNOLOGY Superantigens/*IMMUNOLOGY Support,
Non-U.S. Gov't T-Lymphocytes/*IMMUNOLOGY Transfection Tumor Cells,
Cultured JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).