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™ BUV496 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 496-nm. BD Horizon BUV496 can be excited by the ultraviolet laser (355 nm) and detected with a 515/30 nm filter with a 450LP. Due to the excitation of the acceptor dye by other laser lines, there may be significant spillover into the channel detecting BD Horizon V500 or BV510 (eg, 525/40-nm filter). However, the spillover can be corrected through compensation as with any other dye combination.