The monoclonal antibodies TH6 and 12A5 recognize Folate Receptor 4 (FR4), also known as the membrane folate-binding protein 3 (FBP3). FR4 is a heavily glycosylated 35 kD receptor expressed exclusively in lymphoid tissue and an isoform of the family of receptors that recognize the essential nutrient folic acid. Natural T regulatory cells constitutively express high levels of FR4. Differential expression of FR4 in combination with CD25 can distinguish four functionally distinct CD4+ T cell subpopulations; Natural Tregs, effector T cells, memory-like T cells and Naïve T cells. FR4hi CD25+ expressing CD4+ T cells also express high amounts of Foxp3, GITR and CTLA-4.
Monoclonal antibody TH6 and 12A5 stained CD25+CD4+ T cells at a higher level than other CD4+ or CD8+ T cells. In addition, in vivo injection of TH6 monoclonal antibody reduced the number of CD25+CD4+ T cells and CD25-CD4+ T cells in peripheral blood. Clone 12A5 has been demonstrated to work in western blot. Clones TH6 and 12A5 do not block one another in a flow cytometric assay.
This antibody is conjugated to BD Horizon™ BV605 which is part of the BD Horizon Brilliant™ Violet family of dyes. With an Ex Max of 407-nm and Em Max of 602-nm, BD Horizon BV605 can be excited by a violet laser and detected with a standard 610/20-nm filter set. BD Horizon BV605 is a tandem fluorochrome of BD Horizon BV421 and an acceptor dye with an Em max at 605-nm. Due to the excitation of the acceptor dye by the green (532 nm) and yellow-green (561 nm) lasers, there will be significant spillover into the PE and BD Horizon PE-CF594 detectors off the green or yellow-green lasers. BD Horizon BV605 conjugates are very bright, often exhibiting brightness equivalent to PE conjugates and can be used as a third color off of the violet laser.
