The HIS57 monoclonal antibody reacts with an unknown antigen that is highly expressed by most marginal zone B (MZ-B) cells in the spleen. In contrast, this antigen is weakly expressed, or not expressed at all, by other B-cell subpopulations. Rat MZ-B cells express low levels of CD45R (mAb HIS24) and sIgD and high levels of sIgM. The HIS57 mAb does not stain granulocytes and thymocytes. Immunohistochemical staining of normal spleen sections with HIS57 mAb produced a positive signal in the marginal zone and, to a lesser extent, in B-cell follicles. This marker can be used in combination with CD45R, sIgD, and sIgM t0 identify MZ-B cells in the rat.
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.