MODULATION OF CYTOKINE MESSENGER-RNA EXPRESSION IN DIFFERENTIATED HUMAN MONOCYTIC CELL-LINES FOLLOWING EXPOSURE TO INORGANIC PARTICLES

In these preliminary studies we have examined the effects of in vitro challenge with inorganic dusts on cytokine gene expression by undiffer entiated cells, cells undergoing phorbol 12-myristate 13-acetate (PR?A ) induced differentiation, and on differentiated cells. We have used t hree different human promonocytic cell lines, U937, THP1 and HL60 in a n undifferentiated state and following differentiation with PMA. We fo und that cytokine specific mRNA levels could be modulated by inorganic dusts with known toxic effects, whereas those which are classified as biologically inert had no measurable effects on cytokine gene express ion. These findings were only observed on fully differentiated cells w ith no modulation seen in undifferentiated cells or those undergoing d ifferentiation. (C) 1997 Elsevier Science Ltd.