It is speculated that IgG4 might prevent polyp regrowth, possibly causing a fibrotic disease in the sinuses (36, 37) but IgG4 might also be a step in the class switching into local IgE as IL10 encoding IL10 cytokine that drives immunoglobulin production toward IgG4 has been shown in RNA-sequencing analysis of nasal polyp cells of AERD patients (35). This evidence concerns the gene IL10 and nasal cavity polyp.