Advantage of monoclonal vs. polyclonal antisera in a beta 2-microglobulin radioimmunoassay.

Unassociated human beta 2-microglobulin (beta 2m) and histocompatibility peptide associated beta 2-microglobulin produce significantly different inhibition curves in a competitive binding assay with rabbit anti-beta 2-microglobulin. This difference disallows the use of the rabbit antisera for measuring MHC-beta 2-microglobulin complex concentration using free beta 2m as a standard. Presumably the close amino acid sequence homology between human and rabbit beta 2-microglobulin results in rabbit antisera against a small number of epitopes, some of which are covered or conformationally altered in the MHC-beta 2-microglobulin complex. A monoclonal anti-beta 2-microglobulin antibody, LG1 reacted equally well with both forms of beta 2-microglobulin and is used to measure the concentration of beta 2-microglobulin in the histocompatibility peptide complex.