In detail, we summarize the expression of MHC II on non-professional APCs and CD4+T cells formation by non-professional APCs during lung diseases, such as asthma, chronic obstructive pulmonary disease (COPD), etc. This analysis will help to understand the significance of MHC II mediate multiple effects of crosstalk with CD4+T cells in lung diseases. The gene discussed is CD4; the disease is chronic obstructive pulmonary disease.