IL4 and polyp: This type 2 inflammation process is characterized by eosinophil, lymphocyte, basophil and mast cell infiltration into polyp tissue, driven by T helper 2 (Th2) lymphocytes and group 2 innate lymphoid cells (ILC2) that produce high levels of interleukin-4 (IL-4), IL-5 and IL-13, which are considered key drivers of type 2 inflammation [9–11].