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™ BUV661 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 661-nm. BD Horizon Brilliant BUV661 can be excited by the ultraviolet laser (355 nm) and detected with a 670/25 filter and a 630 nm LP. Due to cross laser excitation of this dye, there may be significant spillover into channels detecting APC-like emissions (eg, 670/25-nm filter).
Due to spectral differences between labeled cells and beads, using BD™ CompBeads can result in incorrect spillover values when used with BD Horizon BUV661 reagents. Therefore, the use of BD CompBeads or BD CompBeads Plus to determine spillover values for these reagents is not recommended. Different BUV661 reagents (eg, CD4 vs. CD45) can have slightly different fluorescence spillover therefore, it may also be necessary to use clone-specific compensation controls when using these reagents.