IL-10 downregulates IL-4-induced IgE production through indirect effects on B cells

Abstract

Abstract Control of allergic disease (and of helminth-associated pathology) is associated with decreased antigen-specific IgE and increased antigen-specific IgG4. Although IL-10 appears to contribute to this process, underlying mechanisms are largely unknown. This study explored how IL-10 differentially regulates human IgE and IgG4 production. PBMCs and highly purified total, naïve (CD27-), and memory (CD27+) B cells were cultured with combinations of IL-4, IL-10, and anti-CD40. Quantitative PCR was done for Cε and Cγ4 germline transcripts (GLTs). IgG and IgE isotypes were quantified from culture supernatants using multiplexed immunoassays. IL-4 induced the production of IgE and IgG4 by PBMCs (IgE: geo mean 16.2-fold above baseline; IgG4: geo mean 4.7-fold). IL-4 also increased expression of Cε and Cγ4 GLTs to 54.1-fold and 5.3-fold above baseline, respectively. Addition of IL-10 significantly (p<0.01) reduced IL-4-induced IgE production to 4.6-fold and expression of Cε GLTs to 24.7-fold above baseline, without affecting IgG4 production or expression of Cγ4 GLTs. In cultures of isolated total B cells and B cell subsets, IL-10 had no significant effect on IL-4-induced IgE production; however, IL-10 increased IL-4-induced IgG4 production over 20-fold. IL-4-induced transcription of Cε and Cγ4 GLTs in isolated B cells was not affected by IL-10. Examination of IL-10 receptor (IL-10R) expression on B cell subsets showed increased frequencies of IL-10R+ memory B cells compared to naïve B cells. These results suggest that IL-10 acts indirectly through accessory cells to downregulate IL-4-induced production of IgE. IL-10 can act directly on B cells to upregulate IL-4-induced production of IgG4, likely downstream of germline transcription.