BALB/c antiarsonate idiotypes: gene complementation necessary for expression.

The expression of two idiotype (id) families (5AF6 and 3C6) associated with the BALB/c p-azophenylarsonate-specific antibody response was examined in 11 mouse strains. Eight strains produced some of one or the other of these two id families with the mean percent expression in the anti-Ar responses of id(+) strains ranging from 8 to 43% for the 5AF6 and from 2 to 10% for the 3C6 idiotype. Four strains of mice (C58, AKR, PL, and RF) thought to have Lyt-3.1-linked VL repertoire differences from other mouse strains (Lyt-3.2) were tested for their capacity to contribute to 5AF6 and 3C6 id expression. The RF strain was capable of producing 5AF6 id and small amounts of 3C6 id. Tests of Lyt-3.1 congenic strains C.AKR (AKR Lyt-3.1 on a BALB/c background) and C.C58 (C58 Lyt-3.1 on a BALB/c background) showed that C.AKR could produce 5AF6 id while C.C58 could not. 3C6 id expression was present but depressed in C.C58 mice compared with the high 3C6 id expression in C.AKR. Breeding studies mating C.C58 (bearing the required Igh-Ca-linked VH genes) to other 5AF6(-) strains showed that gene complementation could result in 5AF6 expression in F1 offspring. 5AF6(-) strains capable of complementation included CBA/J, C57BL/6J, AKR/J, and PL/J. C58/J (from which C.C58 were derived) was the only tested strain that failed to complement for 5AF6 id expression. Additional matings between C58/J[5AF6(-)] and CBA/J[5AF6(-)] showed F1 offspring could produce 5AF6 id, indicating that C58/J can contribute functional VH genes necessary for 5AF6 id expression. Depressed expression of 5AF6 and 3C6 id was noted in mice where the C58/J-derived Lyt-3.1 genotype was present. The possibility that the depression of 5AF6 and 3C6 id expression derived from C58/J mice was due to regulatory influences rather than a lack of the VL structural genes is discussed.