The role of IgG antibodies in allergy and immunotherapy.

In specific immunotherapy (SIT), a beneficial response is associated with an increase in allergen-specific IgG(4) . This does not indicate that IgE-producing B cells have switched to IgG(4) production, because in human DNA, IgE is downstream from IgG(4) . Thus, by conventional switching, B cells should produce IgG(4) before IgE. This presentation discusses three possible hypotheses explaining the favourable association between IgG(4) and SIT, including that SIT causes B cells to become regulatory. Regulatory B cells may produce cytokines like IL-10 that promote IgG(4) production. IgG(4) can undergo in vitro switching to create bispecific antibodies that recognize more than one antigen, which has important consequences for reducing IgE-allergen complexes in immunotherapy.