Figure 1: Model of IgG-mediated DC activation during secondary allergic responses in the lung. During primary sensitization, inhaled allergens are taken up by dendritic cells that then migrate to the draining lymph node to promote differentiation of T cells. Skewing towards a Th2 phenotype results in production of IL-4 and IL-13 that can promote IgE and IgG1 class switching in B cells. The IgG1 can complex with inhaled allergen during a secondary exposure to form ICs that signal through FcγRs on hematopoietic cells to promote allergic responses.