Quiescent human mononuclear cells (MNC) as studied ex vivo express highly specific mRNA patterns of growth factors: We recently demonstrated that unstimulated MNC constitutively express the genes for the A and B chains of platelet-derived growth factor (PDGF). This expression was down-regulated by dietary omega-3 fatty acids. We now report that unstimulated human MNC express the genes for platelet-derived endothelial cell growth factor (PD-ECGF), insulin-like growth factor (IGF-1A, -1B) and transforming growth factor-beta 1 (TGF-beta 1). In contrast, acidic and basic fibroblast GF (FGFs), insulin-like GF-2 (IGF-2), transforming GF-alpha (TGF-alpha) and epidermal GF (EGF) were not expressed in MNC, nor were alpha- and beta- receptors for PDGF. Quantitatively, as measured over a period of six weeks, expression of PD-ECGF was constant, whereas TGF-beta 1, IGF-1A, and IGF-1B were expressed at varying levels and all independently of each other. Dietary omega-3 fatty acids had no effect on gene expression. Our results also indicate that down-regulation of PDGF gene expression represents a specific and possibly therapeutic effect of dietary fish oil supplementation.