Figure 6. No difference in half-life of IgG2 light chain isotypes κ and λ in mice.

(A) Recombinant human IgG2κ and λ in Balb/C mice was injected and measured by total IgG ELISA for a two week period following injection of 200 µg IgG. Calculated half-lives were 7.2±1.48 and 6.4±0.84 days for IgG2κ and IgG2λ. (B) Enrichment of IgG2 κ isoforms was performed as described in Dillon et al 2008. HPLC elution profiles of IgG2 κA and κB structural isomeres on a Dionex ProPac WCX-10 (4.0_250 mm) column are depicted. IgG2κB isoform was generated by incubation of 3 mg/ml IgG2κ in 200 mM Tris buffer at pH 8 with 6 and 1 mM of cysteine and cystamine, respectively. For IgG2κA synthesis 0.9M guanidine hydrochloride (GuHCl) was also added. The samples were kept in the dark and placed at 4°C for 48–72 h. Following incubation the antibody was run on a Zeba spin desalting column (Pierce) for buffer exchange into PBS. (C) The clearance of IgG2λ, IgG2κA, and IgG2κB in Balb/C mice. Calculated half-lives were 4.0±0.58, 5.39±0.85, and 3.7±1.04 days for IgG2κA, IgG2κB and IgG2λ, respectively. (D) Clearance of IgG2κA and IgG2κB in WT and FcγR −/− C57Bl/6 mice. Calculated half-lives were 6.2±2.62, 6.43±1.69, and 7.5±1.89 days for IgG2κA, IgG2κB and IgG2λ, respectively, in WT mice but 1.08±0.28, 1.19±0.23, and 0.7±0.92 days for IgG2κA, IgG2κB and IgG2λ, respectively, in FcRn −/− mice. Graphs in (A, C–D) depict mean and standard deviations of results obtained for 4 mice per group. Half-lives were calculated assuming exponential decay and reported in days ± standard error of means. No significant difference in half-life was detected between the two isotypes.