The T21 monoclonal antibody specifically binds to CD125 which is also known as the alpha subunit of the IL-5 Receptor (IL5RA/IL-5Rα). CD125 is a type I transmembrane protein that belongs to the hemopoietin receptor and Ig gene superfamilies. It is expressed on B cells and eosinophils. CD125 associates with the Common β chain (βc/Bc) subunit, also known as CD131, to form the functional IL-5 Receptor complex. Mouse IL-5 belongs to the hematopoietic growth factor family of cytokines and promotes the growth and differentiation of B cells and eosinophils. Upon binding, the T21 antibody blocks IL-5 binding to its receptor and can inhibit IL-5 induced B-cell proliferation and antibody production.
The antibody was conjugated to BD Horizon™ BV711 which is part of the BD Horizon Brilliant™ Violet family of dyes. This dye is a tandem fluorochrome of BD Horizon BV421 with an Ex Max of 405-nm and an acceptor dye with an Em Max at 711-nm. BD Horizon BV711 can be excited by the violet laser and detected in a filter used to detect Cy™5.5 / Alexa Fluor® 700-like dyes (eg, 712/20-nm filter). Due to the excitation and emission characteristics of the acceptor dye, there may be moderate spillover into the Alexa Fluor® 700 and PerCP-Cy5.5 detectors. However, the spillover can be corrected through compensation as with any other dye combination.