The LC4 monoclonal antibody specifically recognizes the human variable beta 5.1 (Vβ5.1) domain of the beta subunit for the αβ T cell receptor for antigen (TCR αβ). TCR Vβ5.1 is encoded by TRBV5-1 (T cell receptor beta variable 5-1), one of five functional genes within the TRBV5 subgroup in the T cell receptor beta (TRB) locus. The heterodimeric TCR αβ is composed of two disulfide-linked transmembrane glycoproteins, ie, highly variable TCRα and TCRβ chains. These chains are each comprised of an extracellular N-terminal variable (V) region domain followed by a constant (C) region domain, a transmembrane region, and a short C-terminal cytoplasmic tail. The TCR Vβ repertoire is known to be extensive due to the many different combinations of TCR gene segments (Vβ, Dβ, and Jβ) as well as junctional region diversity. TCR Vβ5.1 is variably expressed on subsets of TCR αβ-positive thymocytes and peripheral CD4+ or CD8+ T cells. In association with the CD3 complex of signaling proteins, the TCR αβ recognizes peptide-major histocompatibility complexes (pMHC) that are displayed on other cells to mediate cellular responses. The LC4 antibody is useful for analyzing the levels of TCR Vβ5.1 expressed by individual cells as well as the numbers or frequencies of TCR Vβ5.1-positive cells within test samples. The LC4 antibody can be used to help characterize the TCR Vβ repertoires of T cell populations during health as well as in response to vaccination, infectious disease, aging, transplantation, autoimmunity or cancer.
The antibody was conjugated to BD Horizon™ BUV661 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 with an Ex Max of 348-nm and an acceptor dye with an Em Max at 661-nm. BD Horizon Brilliant BUV661 can be excited by the ultraviolet laser (355 nm) and detected with a 670/25 filter and a 630 nm LP. Due to cross laser excitation of this dye, there may be significant spillover into channels detecting APC-like emissions (eg, 670/25-nm filter).
Due to spectral differences between labeled cells and beads, using BD™ CompBeads can result in incorrect spillover values when used with BD Horizon BUV661 reagents. Therefore, the use of BD CompBeads or BD CompBeads Plus to determine spillover values for these reagents is not recommended. Different BUV661 reagents (eg, CD4 vs. CD45) can have slightly different fluorescence spillover therefore, it may also be necessary to use clone-specific compensation controls when using these reagents.