Using cDNA arrays, we characterized patterns of gene expression in populations of human dendritic cells (DCs) produced for clinical use. Culture and maturation induction of myeloid adherent cells under serum-free conditions yielded DCs with phenotypes similar to those described in serum-based systems. Analysis of gene expression in DCs treated with tumour necrosis factor alpha, soluble CD40L trimer or interferon gamma, however, showed specific patterns for each factor examined. Our studies document the expression of several transcripts that have not hitherto been described in DCs and/or differentially regulated according to the differentiation state of the DCs, and suggest important functional differences among the DC populations examined. In addition, DC maturation directs changes in the levels of mRNA specific for transcriptional regulators that effect the production of cytokines (e.g. BCL-6, c-rel). Other changes observed, including alteration in the gene expression profile of adhesion molecules and chemokine receptors such as CD44H, CD 49B, Rantes R, CXCR5 and CD37, suggest differences in trafficking potential between the populations studied. This broad-based description of DC populations, produced under serum-free conditions, has enabled us to better define intermediate stages of DC maturation as well as the differentiation-inducing effects of cytokines on these cells.