Studies of endobronchial biopsy specimens and BAL fluid of subjects with severe asthma have shown that asthma is associated with elevated bronchial mucosal expression of TSLP and Th1-attracting (IP-10/CXCL10) and Th2-attracting (TARC/CCL17, MDC/CCL22) chemokines [118, 119]. Here, CCL17 is linked to asthma.