INDUCIBLE NITRIC-OXIDE SYNTHASE EXPRESSION IS SELECTIVELY INDUCED IN ASTROCYTES ISOLATED FROM ADULT HUMAN BRAIN

Inducible nitric oxide synthase (iNOS) expression has been shown to be differentially regulated among different cell types and species. In c ultures of primary human fetal glial cells, we have shown that astrocy tes rather than microglia express iNOS. Inthe present study, we extend ed these findings to primary cultures of astrocytes and microglia deri ved from adult human brains. Mixed cultures of adult brain tissue were stimulated with IL-1 beta and IFN gamma, a combination known to induc e iNOS maximally in human fetal cells, and the expression of iNOS was determined by immunocytochemistry. Cell types were determined by morph ology as well as immunocytochemistry for GFAP (astrocytes) and CD68 (m icroglia). The results showed that in cultures of adult human glia, iN OS was expressed following stimulation with cytokines, and the express ion was restricted to astrocytes. Astrocyte iNOS immunoreactivity was detected bath in the cytosol and in a discrete paranuclear region, a p attern noted in human fetal astrocytes. These results demonstrate that the ability to express iNOS is common to both fetal and adult human a strocytes. (C) 1998 Elsevier Science B.V. All rights reserved.