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 BUV615 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome with an Ex Max near 350 nm and an Em Max near 615 nm. BD Horizon Brilliant BUV615 can be excited by the ultraviolet laser (355 nm) and detected with a 610/20 filter and a 595 nm LP. Due to the excitation of the acceptor dye by the blue/yellow-green laser line, there may be significant spillover into channels detecting PE-CF594 like emissions (eg, 610/20-nm filter).