The 536 monoclonal antibody specifically recognizes Vγ 3† T-cell Receptor (TCR)-bearing T lymphocytes, which are the predominant γδ TCR-bearing cells in the early fetal thymus and the adult epidermis of euthymic mice. The first T cells to mature in the embryonic thymus express the Vγ 3 and Vδ 1 TCR chains, and their development is dependent upon IL-7. There is evidence that the Vγ 3 TCR-bearing fetal thymocytes are the precursors of the majority of dendritic epidermal T cells (DEC), which may be replenished in the adult by proliferation in situ rather than by seeding from primary lymphoid organs. Although the Vγ 3 TCR is almost exclusively found in the DEC population, it has been shown that the homing of DEC to the epidermis does not require expression of the Vγ 3 gene segment. Vγ 3 TCR-bearing dermal dendritic cells have also been described. Vγ 3 TCR has also been found on a subset of T lymphocytes in the lactating mammary gland and at the site of antigenic challenge in contact-sensitized mice. Plate-bound 536 antibody activates Vγ 3 TCR-bearing T cells, and Fab fragments of mAb 536 block in vitro stimulation of DEC by keratinocytes.
† Please note that the Vγ 3 designation correlates with the nomenclature of Garman, Doherty, and Raulet; the Vγ 5 designation of Heilig and Tonegawa is equivalent.
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.