Interleukin-13 induces thymus and activation-regulated chemokine (CCL17) in human peripheral blood mononuclear cells.
BACKGROUND
In allergic inflammation involving allergic rhinitis, the predominance of Th(2) lymphocytes is one of the primary causal agents in promotion of the allergic condition. Thymus and activation-regulated chemokine (TARC/CCL17) is a recently identified chemokine that induces the development of Th(2) lymphocytes. One of the sources of TARC has been reported to be peripheral blood mononuclear cells (PBMCs).


OBJECTIVE
We investigated TARC production from PBMCs by the stimulation of specific antigens and Th(2) type cytokines.


METHOD
PBMCs were isolated from both allergic rhinitis patients and healthy volunteers. PBMCs were incubated with cytokine. TARC mRNA expression was examined by real time PCR methods and the amount of TARC production was examined by ELISA.


RESULTS
IL-13 was found to be the most potent inducer for TARC mRNA expression and protein production in PBMCs. Furthermore, tumour necrosis factor alpha and IL-13 synergistically induce TARC. The amount of TARC from allergic rhinitis patients was significantly larger than that from healthy volunteers. Moreover, TARC was induced by a specific antigen, and was 35% inhibited by an anti-IL-13 neutralizing antibody.


CONCLUSION
These results indicate that IL-13 is important in TARC mediated Th(2) lymphocytes infiltration in the nasal mucosa.