Thymosin α 1 activates TLR-dependent signaling. Murine lung DCs (A) and human DC subsets (B), pretreated with thymosin α 1 or the scrambled peptide (sThymosin α 1), were exposed to Aspergillus conidia and assessed for TLR expression by RT-PCR. cDNA levels were normalized against the HPRT gene. None indicates cells exposed to the diluent alone. (C) Production of IL-8 by wild-type or TLR-transfected HEK293 cells stimulated with thymosin α 1 and/or zymosan (10 μg/mL), CpG 2006 (3 μg/mL), and LPS (1 mg/mL). ^*P < .05, stimulated versus unstimulated (None) cells. ^**P < .05, CpG or zymosan + thymosin versus each single agent alone. Bars indicate the standard errors. (D) Activation of NF-κB and p38 on murine lung DCs exposed to Aspergillus conidia, thymosin α 1, or the scrambled peptide, either alone or in combination. The assay was done by probing the cell lysates with specific antiphospho-38 and anti-NF-κB antibodies. Shown are the data from 1 representative experiment of 3.