Lack of IL-10 and IL-13 production by human polymorphonuclear neutrophils.

The ability of polymorphonuclear neutrophils (PMN) to produce and release numerous pro-inflammatory cytokines is now established and play an important role in triggering and maintaining the inflammatory response. We studied the autocrine downregulation of this process by investigating the potential production by human PMN of two major anti-inflammatory cytokines, interleukin 10 (IL-10) and IL-13. The authors' PMN purification method, based in part on immunomagnetic depletion, allows the elimination of all cells known to produce those two cytokines. A wide range of activation conditions were tested and kinetic studies were done. IL-10 and IL-13 proteins were not detected in culture supernatants or cell lysates of PMN from 13 healthy volunteers. This was confirmed by the absence of IL-10 and IL-13 mRNA expression, as shown by RT-PCR. Human PMN thus seem unable to produce or release two of the most potent anti-inflammatory cytokines, IL-10 and IL-13. This could partly account for the persistence of local inflammation, where PMN are the main infiltrating cells.