Alleles of highly homologous rat T cell receptor beta-chain variable segments 8.2 and 8.4: strain-specific expression, reactivity to superantigens, and binding of the mAb R78.
This study addresses the molecular basis of a Tcrb-V polymorphism in the reactivity to the superantigens staphylococcus enterotoxin B (SEB) and the mtv-7 sag (MIs1a) of T cells recognized by the mAb R78, which reacts with the T cell receptor beta-chain variable segment 8.2 (Tcrb-V8.2) of Lewis (LEW) rats. Tcrb-V8.2-like sequences were isolated from liver DNA of the responder strain LEW (I) and the nonresponder strain DA (a) and alleles of the Tcrb-V8.2 and the highly homologous Tcrb-V8.4 were identified. Their expression was analyzed by RNase protection studies and cDNA clones were characterized. A comparison of thymocytes, activated R78+ cells, Con A-stimulated and SEB-stimulated cells allows the following conclusions: the newly identified Lewis allele of Tcrb-V8.4 (Trcb-V8.4I) is nonfunctional due to a frame shift induced by deletion of one nucleotide. The R78 epitope is expressed by Tcrb-V8.2I and Tcrb-V8.4a but not by Tcrb-V8.2a. The implication of this finding for mapping of the R78 epitope and the study of V region usage in experimental autoimmune encephalitis are discussed. Finally, the expression of both Tcrb-V8.2 alleles but not of Tcrb-V8.4a in SEB-stimulated cells defines a polymorphism of the CDR2 and/or CDR4 as the molecular basis of the differential superantigen reactivity.
Institute for Virology and Immunobiology, University of Würzburg, Germany.
A
A
Asmuss
K
K
Hofmann
T
T
Hochgrebe
G
G
Giegerich
T
T
Hünig
T
T
Herrmann
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D001483:Base Sequence; D001666:Binding Sites, Antibody; D005260:Female; D008969:Molecular Sequence Data; D051381:Rats; D011917:Rats, Inbred Lew; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000096:biosynthesis* / Q000235:genetics*; D013045:Species Specificity; D018089:Superantigens / Q000276:immunology*
D000911:Antibodies, Monoclonal; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018089:Superantigens