Intact antiinfluenza virus immune response in targeted kappa-deficient mice.

Immunoglobulins are encoded by genes located in three different loci, the heavy chain (IgH), kappa light chain (Ig kappa), and lambda light chain (Ig lambda) loci. In mice, the kappa/lambda ratio of B cells is 95:5. In a previous study, we reported that kappa gene deletion causes the alternative usage of lambda 1 (93%) and lambda 2 (7%) light chains, and that the kappa anti-TNP repertoire is compensated for by the lambda repertoire even though the latter is clonally restricted in K-/- mice. To investigate the contribution of lambda antibodies to protection against virus, we compared K-/- mice with 129/Sv wild-type mice with respect to immune responses to influenza virus. PR8 virus immunized K-/- and 129/Sv mice showed no difference in the titer of anti-HA antibodies. Furthermore, the same immunized mice had sufficiently high neutralizing antibody titer to prevent infection when challenged with 7.5 x 10(4) TCID50 of PR8 virus. In addition, immunized K-/- mice were resistant to infection with 7.5 x 10(4) TCID50 and 7.5 x 10(5) TCID50 (10 and 100 LD50, respectively) of PR8 virus. Finally, K-/- mice are also capable of inducing cytotoxic T cells. These results suggest that the lambda repertoire can compensate for the kappa repertoire by generating a fully protective neutralizing antibody response.