The pre-B cell receptor (pre-BCR) expressed during the early stages of B lymphocyte development is a heterodimer of immunoglobulin heavy chain (IgH) with surrogate light chain, which is an Ig-light-chain-like molecule composed of the non-covalently linked CD179b (λ5) and CD179a (VpreB) proteins. The pre-BCR is believed to control IgH repertoire selection and proliferation of differentiating B lymphocytes. The R3/VpreB antibody reacts with CD179a and pre-BCR in pre-B-cell lines, but not CD179b alone. It detects pre-BCR on the surface of early B-lineage cell lines. R3/VpreB antibody has been reported to detect both cell-surface and intracytoplasmic surrogate light chain in normal bone marrow. However, in CD179b-deficient (λ5[-/-]) bone marrow, R3 antibody can detect only intracytoplasmic CD179a. At the earliest stages of B chain associates with a complex of glycoproteins, including a nonclassical cadherin, which could be involved in selective adhesion events during B-lymphocyte development.
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.