The OX-22 antibody reacts with CD45RC on pre-B lymphocytes, B cells, CD8+ T suppressor/cytotoxic cells, and a subset of CD4+ T helper (Th) lymphocytes. It weakly reacts with thymocytes. CD45RC is a high-molecular-weight isoform of CD45 (Leukocyte Common Antigen); its level of expression distinguishes subpopulations of CD4+ T cells with Th1-like and Th2-like effector functions. Levels of expression of CD45RC have also been reported to distinguish resting from activated T cells at various stages of maturation. CD45 is a member of the Protein Tyrosine Phosphatase (PTP) family: Its intracellular (COOH-terminal) region contains two PTP catalytic domains, and the extracellular region is highly variable due to alternative splicing of exons 4, 5, and 6 (designated A, B, and C, respectively), plus differing levels of glycosylation. The CD45 isoforms detected in the rat are cell type-, maturation-, and activation state-specific. The CD45 isoforms play complex roles in T-cell and B-cell antigen receptor signal transduction.
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.