The KT50 antibody reacts with some members of the Vα 8 T-cell Receptor (TCR) subfamily of mice having the a, b, c, and d haplotypes of the Tcra gene complex (e.g., all strains tested). It recognizes an epitope in the CDR1 of Vα 8.3, but not Vα 8.2, TCR subfamily member, as does the B21.14 mAb (Cat. no. 553374). Site-directed mutagenesis has identified three amino acids which are necessary for antibody reactivity and which are unique to Vα 8.3 among the five functional Vα 8 TCR subfamily members. On a common H-2[k] background, the frequency of Vα 8.3 TCR-bearing T lymphocytes is higher in Tcra[a/a] mice than in Tcra[a/b] mice. Furthermore, studies of congenic strains suggest that CD8+ Vα 8.3 TCR-bearing T lymphocytes undergo negative selection in mice expressing MHC class I antigens of the H-2[d] haplotype.
The antibody was conjugated to BD Horizon™ BV786 which is part of the BD Horizon Brilliant™ Violet family of dyes. This dye is a tandem fluorochrome of BD Horizon BV421 with an Ex Max of 405-nm and an acceptor dye with an Em Max at 786-nm. BD Horizon BV786 can be excited by the violet laser and detected in a filter used to detect Cy™7-like dyes (eg, 780/60-nm filter).