Another study compared cell populations of CD4+ and CD8+ T cells, the CD4+/CD8+ ratio, the concentrations of the cytokines interleukin (IL)-2, IL-4, and IL-6, and the concentrations of immunoglobulin E (IgE) and nitric oxide (NO) in middle ear effusion (MEE) and the peripheral blood of 50 children with OME and 50 healthy children. Here, CD4 is linked to otitis media with effusion.