A radioimmunoassay for the detection of idiotypes in alloantigen reactive mouse sera and in normal mouse sera.

A radioimmunoassay was developed for characterization of the binding between rabbit antiserum and idiotypes in B6 anti-H-2k antisera. It was a double precipitation assay using iodinated F(ab')2 fragments prepared from B6 anti-H-2k antisera as antigen. Suitable absorptions made the non-specific binding very low, and thus this assay was well suited for detecting idiotypes in preparations, that mainly contained other forms of immunoglobulin than the idiotype. That the rabbit antiserum reacted with idiotypes was demonstrated by the use of F(ab')2 fragments in inhibition assays where B6 anti-H-2k and ABY anti-H-2k antisera could be used as effective inhibitors in contrast to B6 anti-H-2q and ABY anti-H-2k antisera. Idiotype was also found in the sera of normal B6 mice and as much as 0.05% of the immunoglobulin molecules expressed the idiotype. The inhibition assay was suitable for quantitation of idiotypes, since ABY anti-H-2k antisera could be used as effective inhibitors in contrast to B6 anti-H-2q and ABY anti-H-2k antisera. Idiotype was also found in the sera of normal B6 mice and as much as 0.05% of the immunoglobulin molecules expressed the idiotype. The inhibition assay was suitable for quantitation of idiotypes, since ABY anti-H-2k antisera could be used as effective inhibitors in contrast to B6 anti-H-2q and ABY anti-H-2k antisera. Idiotype was also found in the sera of normal B6 mice and as much as 0.05% of the immunoglobulin molecules expressed the idiotype. The inhibition assay was suitable for quantitation of idiotypes, since the reproducibility of the assay through a long period was high.