BIOFILM CAUSES DECREASED PRODUCTION OF INTERFERON-GAMMA

Interferon-gamma, a cytokine, is produced by lymphocytes when they are stimulated by cytokines from activated macrophages, and is essential for macrophage-mediated bactericidal operations, To investigate whethe r a strain of bacteria can activate macrophages and lymphocytes, the i nterferon-gamma levels may thus be measured, Current literature mainta ins that peritoneal dialysis patients with recurrent peritonitis have ''unhealthy'' macrophages and lymphocytes unable to produce interferon -gamma, but that the administration of interferon improves the rates o f peritonitis. In an in vitro experiment, Staphylococcus epidermidis, in both its planktonic and biofilm forms, was added to a suspension of peritoneal dialysis effluents, macrophages, and healthy peripheral bl ood lymphocytes, which were incubated at 37 degrees C for 18 h and the n centrifuged, Subsequent levels of interferon-gamma were measured in the supernatants. Three such experiments were done with peritoneal mac rophages and dialysis effluents collected from each of the three diffe rent patients involved in the study, It was found that little or no in terferon: gamma (0.42 +/- 0.17 U/mL) was produced when biofilm bacteri a were tested, but significant amounts of interferon-gamma (9.25 +/- 4 .63 U/mL) resulted in conjunction with the planktonic form of the same bacteria. To eliminate experimental errors, all conditions were left identical, appropriate control groups were added, and each of the thre e experiments was duplicated. These in vitro data therefore provide ne w insight in the role of biofilm in the pathogenesis of recurrent peri tonitis in peritoneal dialysis patients, Further clinical studies are required.