A gene linked to the heavy-chain allotype I alpha (1a) controls for the expression of idiotype Ox-r1 in the rat.

A rabbit antiserum prepared against purified anti-2-phenyl-oxazolone (phOx) antibodies of AVN rats detects a common idiotype called Ox-r1. This idiotype was also present in anti-phOx antibodies of AS and (AS x LEP)F1 hybrid rats but not in the antibodies of LEP rats. Antisera of (AS x LEP) x LEP backcross rats either resembled F1 hybrid sera (7 rats) or LEP sera (8 rats) in the idiotype assay. All idiotype-positive backcross rats but none of the idiotype negative backcross rats had the I alpha (1) allotype a. The likelihood that such a distribution was due to a chance is approximately 0.0002. The data suggest that the presence of idiotype Ox-r1 in the antisera of AS rats and their progeny is controlled by a gene (or genes) linked to the 1g heavy-chain allotype locus I alpha (1).