Interleukin-13 down-regulates the expression of neutrophil-derived macrophage inflammatory protein-1 alpha

Abstract.

Objective and Design: To determine whether interleukin-13 (IL-13) possesses anti-inflammatory properties with respect to polymorphonuclear neutrophils (PMNs). Effects of IL-13 on production of the chemokine, macrophage inflammatory protein-1 alpha (MIP-1α), by PMNs were analyzed.¶Subjects: Human peripheral blood PMNs obtained from healthy volunteers.¶Methods: PMNs were stimulated by lipopolysaccharide (LPS) and/or IL-13 for selected periods of time, and MIP-1α expression was assessed by ELISA and Northern blot analysis.¶Results: IL-13 suppressed expression and production of PMN-derived MIP-1α mRNA and protein in a dose- and time-dependent manner. Inhibition of protein synthesis caused significant enhancement of MIP-1α mRNA expression. The inhibitory activity of IL-13 was abrogated, however, in the presence of cycloheximide, suggesting that IL-13's effect was via synthesis of de novo repressor protein(s).¶Conclusions: PMN-derived chemokines are regulated by both proinflammatory and immunomodulatory cytokines. The coordinated production of these substances is likely to be important in the orchestration of inflammatory and immune responses.