Major injury induces increased production of interleukin-10 in human granulocyte fractions

Patients with severe trauma or polytrauma frequently acquire alterations in immune functions which are correlated to dysbalanced cytokine synthesis. I n these settings the role of polymorphonuclear neutrophil granulocytes (PMN ) as cytokine-producing cells is less well characterized. The immunosuppres sive role of interleukin (IL)-10 is well known, and increased systemic IL-1 0 levels are related to the severity of injury and to posttraumatic complic ations. We determined concentrations of IL-10 in culture supernatants of 30 individual PMN fractions isolated from 18 severely traumatized patients (1 5 polytraumata, Injury Severity Score: 18-41, 3 severely burned patients) a dmitted to intensive care units. IL-10 was analyzed by ELISA (R&D Systems, Wiesbaden, Germany). PMN were isolated from EDTA-anticoagulated peripheral blood employing a one-step procedure based on a discontinuous double Ficoll gradient. The cells [1x10(6)/ml RPMI 1640 supplemented with 10% fetal calf serum and 25 mM N-(2-hydroxyethyl)-piperazine-N'-(2-ethanesulonic acid] we re stimulated with 0.05% heat-killed Staphylococcus aureus (Pansorbin, Calb iochem-Novabiochem, Bad Soden, Germany) for 24 h using cell culture conditi ons. Our results show that PMN fractions of traumatized patients produce si gnificantly (P<0.008) higher amounts of IL-10 (354+/- 95 pg/ml, n = 30) tha n normal healthy donor cells (125+/- 95 pg/ml, n = 7). IL-10 release from P MN fractions exceeded the release from isolated patients' peripheral blood mononuclear cells induced by similar stimulation or by stimulation with tox ic shock syndrome toxin-l (10 ng) and concanavalin A (2 mu g). Our results provide evidence that PMN fractions play an active role in the development of posttraumatic immunosuppression by autocrine or paracrine mechanisms, fo r example, by suppressing one's own antimicrobial activities or determining the development of T-cell responses via their ability to release IL-10.