The CRCBT-02-001 monoclonal antibody specifically binds to human CD364 which is also known as Peptidase inhibitor 16 (PI-16) or Protease inhibitor 16. PI-16 is a glycophosphatidylinositol-linked, 436 amino acid surface glycoprotein. It is a member of the cysteine-rich secretory protein (CRISP) family and is likewise known as CRISP9. PI-16 is a putative serine protease inhibitor and can serve as a binding protein for PSP94 (prostate secretory protein of 94 amino acids) termed PSPBP. Serum levels of PSP94 and PI-16 can reportedly serve as key targets for prostate cancer research. PI-16 is highly expressed by the activated/memory, FoxP3-bright subsets of regulatory T cells. PI-16-positive regulatory T cells expressed uniformly high levels of the chemokine receptors, CCR4 and CCR6, when compared with PI-16-negative T regulatory cells. The results suggest that the CCR4+CCR6+ regulatory T cells are capable of homing to inflammatory sites and regulating effector T cells such as CCR4+CCR6+ Th17-like cells. PI-16 is also expressed by subsets of memory CD4+ and CD8-bright T cells. It is not expressed by B cells or monocytes.
The antibody was conjugated to BD Horizon™ BV786 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 786-nm. BD Horizon BV786 can be excited by the violet laser and detected in a filter used to detect Cy™7-like dyes (eg, 780/60-nm filter).