The UP-H1 monoclonal antibody recognizes Immune receptor expressed by myeloid cells 2 (IREM-2) which is also known as CD300 antigen like family member E (CD300e), CMRF35-like molecule 2 (CLM2), or Polymeric immunoglobulin receptor 2 (PIgR2). IREM-2 is a 34 kDa type I transmembrane glycoprotein which belongs to the CMFRF35 subfamily of the immunoglobulin (Ig) superfamily. IREM-2 is expressed on monocytes, macrophages and myeloid dendritic cells (mDCs), but not on lymphoid dendritic cells or granulocytes. IREM-2 associates with DAP-12, an ITAM-containing adapter molecule, which provides activating signals. Crosslinking of IREM-2 leads to intracellular calcium mobilization, release of proinflammatory cytokines such as TNF, and increased expression of activation markers on monocytes and mDCs. IREM-2 activation of mDCs can reportedly enhance the alloreactive response of naive T cells.
The antibody was conjugated to BD Horizon™ BV650 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 650-nm. BD Horizon BV650 can be excited by the violet laser and detected in a filter used to detect APC-like dyes (eg, 660/20-nm filter). Due to the excitation and emission characteristics of the acceptor dye, there will be spillover into the APC and Alexa Fluor® 700 detectors. However, the spillover can be corrected through compensation as with any other dye combination.