Modulation of cytokine mRNA expression in differentiated human monocytic cell lines following exposure to inorganic...

In these preliminary studies we have examined the effects of in vitro challenge with inorganic dusts on cytokine gene expression by undifferentiated cells, cells undergoing phorbol 12-myristate 13-acetate (PMA) induced differentiation, and on differentiated cells. We have used three different human promonocytic cell lines, U937, THP1 and HL60 in an undifferentiated state and following differentiation with PMA. We found 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 expression. These findings were only observed on fully differentiated cells with no modulation seen in undifferentiated cells or those undergoing differentiation.