In guinea pig purified antihapten antibodies, the proportion of molecules bearing the κ- or λ-type of L chains (K or L molecules) may diverge markedly from that found in normal γ2-globulins. This has been evaluated by precipitation of I131-labeled antibody preparations using a specific anti-λ-chain antiserum. Anti-DNP antibodies isolated 3 wk after immunization of guinea pigs with DNP65-BGG antibodies, contain less than 1% of L molecules, while in pipsyl antibodies, isolated from the sera of animals immunized with pipsyl-BGG, the proportion of L molecules is significantly greater than in normal γ2-globulins.
Anti-DNP antibodies produced against conjugates of this hapten with carriers other than BGG (BSA, OVA, or poly-L-lysine) or with BGG with a small number of DNP groups (DNP10-BGG) contained a greater proportion of λ-chain bearing molecules than anti-DNP antibodies isolated from late sera of guinea pigs immunized with highly conjugated DNP65-BGG. An increased percentage of L molecules was detected in preparations of anti-DNP65-BGG antibodies isolated early (10 days), when compared to those isolated later during the course of immunization. However, the level of L molecules in all these anti-DNP antibody preparations was always considerably below that present in normal γ2-globulin. The relative amounts of L molecules in distinct immunoglobulin families (γ1 and γ2) in antibody preparations isolated from individual animals was remarkably similar.