Transient monocyte release of interleukin-10 in response to traumatic brain injury

A significant component of the immune response to trauma results in the sys temic presence of cytokines which have the potential to suppress the patien t's immune response to infection and contribute to post-injury complication s. We assayed peripheral blood leukocytes obtained from 10 patients with he ad trauma to determine their production of interleukin (IL). Serum was assa yed for the presence of IL-10, TGF beta(1), and IFN gamma by ELISA. Periphe ral blood leukocytes were screened for intracellular IL-10 and lFN gamma by fluorescence-activated flow cytometry, and cytokine-specific mRNA was dete cted by the polymerase chain reaction. We detected an immediate, but transi ent, presence of IL-10 in the sera of all 10 patients who suffered head tra uma. IL-10-specific intracytoplasmic immunofluorescence was also detected i mmediately after injury in peripheral blood monocytes, but not in lymphocyt es or granulocytes. IL-10-specific mRNA was detected in peripheral blood le ukocytes in only 50% of patients immediately after injury, when the highest serum levels of IL-10 were observed. Our data indicates that release of pr e-formed IL-10 by monocytes contributes to the presence of IL-10 found in p atient peripheral blood immediately after head injury.