MT4 (6B6) reacts with the 190, 205 and 220 kDa isoforms of the glycoprotein cell-surface antigen, CD45RB. The antigen is expressed primarily on a subset of human B and T lymphocytes, monocytes, macrophages and granulocytes (weak). CD4+, CD45RA- (memory T cells) cells show a differential expression of CD45RB. Bright CD45RB expression correlates with higher proliferation and IFNγ production when compared with dim CD45RB expression. CD45RB expression may be a mechanism for fine-tuning the responsiveness of memory cells in vivo.
The antibody was conjugated to BD Horizon BUV615 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome with an Ex Max near 350 nm and an Em Max near 615 nm. BD Horizon Brilliant BUV615 can be excited by the ultraviolet laser (355 nm) and detected with a 610/20 filter and a 595 nm LP. Due to the excitation of the acceptor dye by the blue/yellow-green laser line, there may be significant spillover into channels detecting PE-CF594 like emissions (eg, 610/20-nm filter).