The MRα4-1 antibody reacts with the integrin α4 chain, which is expressed as a heterodimer with either of two β chains, β1 or β7. The α4β1 integrin (VLA-4, CD49d/CD29) is expressed on peripheral T and B lymphocytes, thymocytes, and monocytes; while the α4β7 integrin (LPAM-1) is expressed on peripheral lymphocytes. These integrins mediate a variety of cell-cell and cell-matrix interactions, recognizing the ligands CD106 (VCAM-1), MAdCAM-1, and fibronectin. It has been reported that soluble mAb MRα4-1 partially inhibits in vitro binding of VCAM-1 and mast cells to fibronectin and inhibits the enhanced degranulation of IgE-sensitized RBL-2H3 basophilic leukemia cell line induced on fibronectin-coated plates. Furthermore, plate-bound MRα4-1 antibody enhances the degranulation of IgE-sensitized RBL-2H3 cells; and subcutaneous injection of MRα4-1 mAb, along with anti-CD49e and anti-CD61 antibodies, inhibits experimentally induced passive cutaneous anaphylaxis.
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.