Abstract
A monoclonal antibody, CMRF1, to human β2-microglobulin (β2m) was used to purify antigen to develop an in-house β2m radioimmunoassay. This immunoadsorption purified material was used to prepare a rabbit anti-β2m serum and was radiolabeled for the radioimmunoassay. The assay compared favourably with a widely used commercial radioimmunoassay but the immunological potency of the in-house standard was lower than that of the commercial reagent. This potency difference was not accounted for by antigenic denaturation. Subsequent two-dimensional gel electrophoresis revealed a second 12,000 dalton protein with a higher isoelectric point than β2m in the immunoadsorption purified material, which was also present, although in lesser amounts, in the commercial product. The different relative content of the additional 12,000 dalton protein appeared to explain the immunological potency difference between the in-house and the commercial standard. These results strengthen suggestions that there may be some heterogeneity or polymorphism in human β2m.