IL-5 was detected in the middle ear mucosa and effusions in atopic patients with persistent OME. 110, 116, 117 The expression of IL-5 mRNA in mucosa was up-regulated and correlated with increased expression of major basic protein (cell marker for eosinophils) and CD3 (cell marker for activated T lymphocytes). 116 Examination of the cytokine profile in the middle-ear specimens showed an increased number of cells expressing IL-5 and its correlation with the percentage of eosinophils and T lymphocytes. 110 Correlation between the percentage of eosinophils and levels of IL-5 in effusions was particularly striking in OME patients with asthma, 117 suggesting that middle ear eosinophilia could be dependent not only on the local, but also on the general level of IL-5 production. The percentage of cells expressing IL-5 in effusions of atopic patients was the same or slightly higher compared with cells expressing IL-4; 110 this was evidence that both cytokines IL-5 and IL-4 contributed to development of allergic inflammation in the middle ear.