Bronchoalveolar lavage (BAL) fluid levels of type 2 chemokines TARC/CCL17 and MDC/CCL22, most probably produced by alveolar aaMØ, were increased after segmental challenge and correlated with airway eosinophils and concentrations of IL-5 and IL-13 in allergic asthma [125,126], and higher numbers of arginase-1-positive cells, predominantly MØ, in BAL cells, were reported in allergic asthmatic as compared with control subjects [127]. This evidence concerns the gene CCL17 and allergic asthma.