Figure 3.

The interplay between antigen-presenting cells (APC), invariant NKT cells, Th2-cells and B-cells, with examples from what is described from reactions to pollen lipids. The Toll-like receptors 2 and 4, on the surface of APCs, as well as the nuclear receptor PPARg in their interior, can bind to lipids, which then are presented by Cd1d molecules on their surface. Then, the Cd1d-bound lipid can be recognized by T cell receptor (TCR) on the surface of the iNKT. Simultaneously, the APC produces cytokines, which skew cytokine production in the iNKT to promote a Th2-inflammatory response. The APC will in turn be stimulated by the iNKT cytokine production, and they will engage in an activation loop, reciprocally stimulating the production of Th2 cytokines (e.g., IL-4, IL-5, IL-13).