IVIGs increase de novo synthesis of IgG.

Purified human B lymphocytes were cultured with IL-4 and irradiated L4.5 during 14 days with 10 mg/mL sucrose and 6 mg/mL human serum albumin (control; ■) or with 10 mg/mL IVIGs (IVIGs; ▪). Cells were extensively washed and transferred without IVIGs in MEM without methionine as described in “Materials and methods.”³⁵S-IgG content was evaluated in culture supernatants after 4 hours and 22 hours. Error bars are showing standard deviation for triplicates. Both IVIG preparations showed similar results. These results are representative of 3 independent experiments.