STREPTOMYCES SPORES FROM MOLDY HOUSES INDUCE NITRIC-OXIDE, TNF-ALPHA AND IL-6 SECRETION FROM RAW264.7 MACROPHAGE CELL-LINE WITHOUT CAUSING SUBSEQUENT CELL-DEATH

The current view is that only bacterial lipopolysaccharide (LPS) and g amma interferon (IFN gamma) are able to alone activate macrophages to secrete nitric oxide (NO), probably a causative agent of cell death. M oreover, some cytokines and gram positive pathogens together with IFN gamma induce NO-production. Surprisingly, spores of Streptomyces sp., which are mesophilic gram-positive bacteria found in mouldy houses, st imulated RAW264.7 macrophages to produce pro-inflammatory cytokines, t umor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6), and i nduced the expression of inducible NO-synthase (iNOS) with a subsequen t NO-production. However, the Streptomyces spores did not kill NO-prod ucing macrophages, as did both LPS and gram negative bacteria Pseudomo nas fluorescens, strong inducers of cytokine- and NO-production. These results imply that Streptomyces sp., induced cytokine and NO-secretio n, may play a role in the responses evoked by exposure to these microb es. Moreover, factors other than, or in addition to NO, are necessary for cytotoxicity in murine macrophages. (C) 1997 Elsevier Science B.V.