CD4 and Increased total eosinophil count: Immunological hallmarks of allergic asthma include eosinophilia in patient bronchoalveolar lavage (BAL) fluid, sputum or bronchial biopsies, Th2 polarised CD4+ T cells secreting type 2 cytokines (including IL-4, IL-5 and IL-13), and IgE antibody.