Human immunoglobulin G stimulates human adipocyte lipogenesis.

The effect of human IgG on human adipocytes has been investigated. Polyclonal IgG prepared from sera of normal subjects, monoclonal IgG from sera of patients with myeloma and IgG harvested from lymphocytes cultures were equally potent in stimulating lipogenesis in human adipocytes. Fc fragments prepared from IgG fractions also stimulated lipogenesis, whereas Fab fractions were inactive. Pre-incubation of IgG and Fc fragments with gamma-chain specific anti-IgG and anti-Fc antisera neutralised the stimulatory activity of both IgG and Fc fractions. The stimulatory effect of IgG on lipogenesis was demonstrated both on adipocyte suspensions and on adipose tissue. These data demonstrate that human IgG has a specific stimulatory effect on lipogenesis by human adipocytes and that this effect is mediated through the Fc moiety.