Investigation of adenoids in patients with recurrent otitis media 92,111 resulted in the following important findings: (1) expression and secretion of IL-4 was detected in adenoids; (2) adenoidal lymphocytes produced the same level of IL-4, or even slightly more, compared with the patient's peripheral blood lymphocytes; 92 and (3) the epsilon germline transcripts for IgE were detected in the adenoids and the level of IgE epsilon germline transcript expression was dependent on the level of IL-4 mRNA expression. 111 This local IL-4-induced immunoglobulin class switching to IgE in the adenoids was considered the essential molecular process contributing to chronic inflammation in the middle ear and promoting the pathogenesis and persistence of OME.