Radioprotective 105 (RP105, CD180) is a type 1 transmembrane protein of 105 kDa with extracellular leucine-rich repeats (LLRs) and a short cytoplasmic tail. RP105, assigned as CD180, is similar to Drosophila Toll in the extracellular LLRs. Radioprotective 105 (RP105, CD180) expression is largely restricted to immune cells including CD19+ B cells and macrophages. Histological studies showed that RP105 is expressed mainly on mature B cells in mantle zones. Antibody-mediated (RP/14) cross-linking of RP105 induces resistance against irradiation-induced apoptosis, B-cell proliferation, and up-regulation of a costimulatory molecule B7.2, revealing RP105 as a potent regulator of B-cell activation. RP105 (CD180) has an important role in B-cell activation by LPS. It is important to note that RP105 associates with MD1, which is in this context important for RP105 with respect to B-cell surface expression and LPS recognition and signalling. MD-1 seems to be requisite for efficient expression of RP105.
For flow cytometry, dilutions to be used depend on detection system applied. It is recommended that users test the reagent and determine their own optimal dilutions. The typical starting working dilution is 1:50.