Paraproteins and primary lymphoma in SJL mice. I. Individuality of idiotypes on paraproteins

The isotype distribution and idiotypic determinants of paraproteins (PP) found in sera from aging SJL mice were studied. One or more PP were found in 79% of 9-11 month old mice; the isotypes were γ1 ≥ α ≥ γ2a ≫ γ3 ≫ γ2b. There was a significant tendency for the PP to occur in pairs or triplets, multiple PP being found in 35% of the mice without an evident association between any two isotypes. Rabbit anti-Id was prepared against four isolated PP, two γ1 and two γ2a. Inhibition of anti-Id-Id interaction was specific for the immunizing PP only and was absent with all other PP studied (8 γ1 and 10 γ2 PP) and with normal SJL Ig. It is concluded that SJL PP fail to exhibit cross-reactive idiotypes and show a wider range of isotype distribution than was previously suspected, although PP of μ, δ, and ε{lunate} isotypes are absent.