IgE-activated mast cells enhance TLR4-mediated antigen-specific CD4+ T cell responses

Mast cells are potent mediators of allergy and asthma, yet their role in regulating adaptive immunity remains ambiguous. On the surface of mast cells, the crosslinking of IgE bound to Fc epsilon RI by a specific antigen recognized by that IgE triggers the release of immune mediators such as histamine and cytokines capable of activating other immune cells; however, little is known about the mast cell contribution to the induction of endogenous, antigen-specific CD4(+) T cells. Here we examined the effects of specific mast cell activation in vivo on the initiation of an antigen-specific CD4(+) T cell response. While CD4(+) T cells were not enhanced by Fc epsilon RI stimulation alone, their activation was synergistically enhanced when Fc epsilon RI activation was combined with TLR4 stimulation. This enhanced activation was dependent on global TLR4 stimulation but appeared to be less dependent on mast cell expressed TLR4. This study provides important new evidence to support the role of mast cells as mediators of the antigen-specific adaptive immune response.

Automated summary

Mast cells play a significant role in releasing immune mediators in allergies and asthma, but their role in regulating adaptive immunity is still unclear. Research found that the activation of CD4(+) T cells is synergistically enhanced when Fc ε RI activation is combined with TLR4 stimulation, supporting the role of mast cells as mediators of the antigen-specific adaptive immune response.