About CD4
This gene encodes the CD4 membrane glycoprotein of T lymphocytes. The CD4 antigen acts as a coreceptor with the T-cell receptor on the T lymphocyte to recognize antigens displayed by an antigen presenting cell in the context of class II MHC molecules. The CD4 antigen is also a primary receptor for entry of the human immunodeficiency virus through interactions with the HIV Env gp120 subunit. This gene is expressed not only in T lymphocytes, but also in B cells, macrophages, granulocytes, as well as in various regions of the brain. The protein functions to initiate or augment the early phase of T-cell activation, and may function as an important mediator of indirect neuronal damage in infectious and immune-mediated diseases of the central nervous system. Multiple alternatively spliced transcript variants encoding different isoforms have been identified in this gene. [provided by RefSeq, May 2020]

About Brilliant Violet 650
Brilliant™ Violet 650 (BV650) is a red-emitting tandem fluorophore that can be excited by the 405 nm Violet laser and collected using a 660/20 bandpass filter. BV650 has an excitation peak at 405 nm and an emission peak at 645 nm. Due to its unique Stokes shift, not many dyes have identical excitation and emission spectrums, but the nearest alternatives include SuperBright 645, Qdot® 655 and eFluor™ 650NC (ThermoFisher). BV650 exhibits a medium level of brightness and is most often used in flow cytometry, specifically, it is an alternative to nanocrystals used for intracellular flow. This dye is part of the Brilliant™ Violet dye line of fluorescent polymers. Brilliant™ Violet 421 polymer is employed as the donor molecule in a series of tandem dyes with acceptor molecules emitting at various points across the visible light spectrum. The Brilliant™ Violet dyes are a superior alternative to QDot nanocrystals and similar to SuperNova dye from Beckman Coulter and StarBright dyes from Bio-Rad.