Frequency of λ light chain subtypes in mouse antibodies to the 2,4-dinitrophenyl (DNP) group

Of the three λ chain subtypes made by inbred mice, chains of the λ1 subtype are much more frequent than those of the other subtypes (λ2,λ3) in antibodies (Ab) to those few antigenic structures that are known to elicit responses, in which λ chains are the predominant type of light chain [(4-hydroxy-3-nitrophenyl)acetyl (NP) and dextran]. The reasons for the frequency differences are not understood, and the large difference between the λ1 and λ3 frequencies is particularly puzzling, because in nearly all (about 95%) chains of these subtypes the N-terminal 97 or 98 amino acids are endoded by the same Vλ-gene segment. In an effort to identify an Ab response that has different λ subtype frequencies, we analyzed the light chains of the Ab made by BALB/c and B6 mice in response to 2,4-dinitrophenylated chicken gamma globulin (DNP-CGG). We found that approximately 40% of the elicited anti-DNP molecules had λ chains and of these approximately 40% were of the λ2 or λ3 subtype. Polyacrylamide gel electrophoresis indicated that the λ2 and λ3 chains were about equally abundant. Similar λ subtype frequencies were found in the anti-DNP Ab produced by the hybridomas made with spleen cells from the same immunized mice. In the anti-DNP Ab elicited by DNP-CGG and in the anti-NP Ab elicited by NP-CGG the different λ subtype frequencies (λ1/λ2 + λ3 = ca. 1.0-1.5 in anti-DNP and ca. 30 in anti-NP) were unaffected by immunizing mice with each of these antigens alone or with a mixture of the two. This finding, though preliminary, suggests that isotype-specific regulatory T cells are not responsible for the markedly different λ subtype frequencies in anti-DNP and anti-NP Ab.