PHAGOCYTE FUNCTION AND CYTOKINE PRODUCTION IN COMMUNITY-ACQUIRED PNEUMONIA

Background - It is possible that many deaths from pneumonia may involv e the generation of inflammatory mediators and tissue damage by activa ted phagocytes. To test this hypothesis phagocyte function, plasma lev els of interleukin 6 (IL-6), tumour necrosis factor alpha (TNF alpha), and soluble interleukin 2 receptor (IL-2R), disease severity, and out come have been examined in 46 patients with community acquired pneumon ia. Methods - Polymorphonuclear leucocyte (PMNL) and monocyte function were measured daily by chemiluminescence in these patients during the first week of admission, and cytokine levels were subsequently determ ined by ELISA. A series of 61 healthy individuals were used as a contr ol group for the chemiluminescence results. Results - There was eviden ce of phagocyte, particularly PMNL, activation on admission in 76% of the patients. Most patients (86%) also had raised IL-2R levels on admi ssion. IL-6 and unbound TNF alpha were present in 23% and 41% of patie nts at varying times during the course of the disease. There was littl e correlation between measurements of cytokine or phagocyte levels and outcome or indicators of disease severity, although this may be becau se of the small number of patients included in this preliminary study. Conclusions - These results are consistent with the hypothesis that a ctivated phagocyte function and raised levels of circulating cytokines may contribute to the pathogenesis of community acquired pneumonia. T here are striking similarities in this respect between pneumonia, adul t respiratory distress syndrome, and sepsis.