Beryllium-specific immune response in primary cells from healthy individuals

The effect of beryllium (Be) exposure has been extensively studied in patients with chronic beryllium disease (CBD). CBD patients carry mutated MHC class II alleles and show a hyperproliferation of T cells upon Be exposure. The exact mechanism of Be-induced T-cell proliferation in these patients is not clearly understood. It is also not known how the inflammatory and suppressive cytokines maintain a balance in healthy individuals and how this balance is lost in CBD patients. To address these issues, we have initiated cellular and biochemical studies to identify Be-responsive cytokines and other cellular markers that help maintain a balance in healthy individuals. We have established an immune cell model derived from a mixture of peripheral blood mononuclear cells (PBMCs) and dendritic cells (DCs). In this article, we demonstrate that pro-inflammatory cytokine IL6 shows decreased release whereas suppressive cytokine IL10 shows enhanced release after 5-10 h of Be treatment. Furthermore, the Be-specific pattern of IL6 and IL10 release is dependent upon induction of threonine phosphorylation of a 45 kDa cytosolic protein (p45), as early as 90 min after Be treatment. Pharmacological inhibition of phosphatidylinositol 3' kinase (PI3'K) by wortmannin and p38 mitogen-activated protein kinase (MAPK) by SB203580 reveal that PI3'K mediates Be-specific p45 phosphorylation and IL6 release, whereas p38 MAPK regulates the release of IL6 and IL10 and the phosphorylation of p45 independent of metal-salt treatment. While the IL10 and IL6 release pathways are uncoupled in these cells, they are linked to phosphorylation of p45. These findings suggest that the balance between IL10 and IL6 release and the correlated p45 phosphorylation are important components of the Be-mediated immune response in healthy individuals.