IL4 and anaphylaxis: IL-4 derived from T cells, type 2 innate lymphoid cells (ILC2s), and MCs may contribute to oral anaphylaxis.16,17,51 Both the increase in IL-4 serum concentrations and enhanced passive oral anaphylaxis were abolished in OVA + SEB-sensitized Cd4-cre Il4/13flox/flox mice, which selectively lack IL-4 and IL-13 in T cells, compared with Il4/13flox/flox controls (Figures 3J and 3K).