Effect of glucocorticoid treatment on BAFF and APRIL expression in patients with immune thrombocytopenia (ITP).

Immune thrombocytopenic purpura (ITP) is an idiopathic bleeding disorder. B cell activating factor (BAFF) and 'A proliferation-inducing ligand' (APRIL) have regulatory effects on B and T cells and may represent relevant factors in the pathogenesis of ITP. Serum levels and gene expression were investigated in ITP patients. Both BAFF and APRIL serum levels were significantly elevated in active ITP. However, gene expression analysis revealed both factors to have a tendency toward downregulation. Glucocorticoid treatment significantly reduced BAFF but not APRIL serum levels, which may be mediated by differences in transcription factor binding sites. The glucocorticoid receptor binding site is present in the BAFF promotor region, but not in the APRIL promotor region. Prednisolone in combination with vitamin D3 may be effective in reducing APRIL serum levels. In conclusion, glucocorticoid treatment exerts different regulatory effects on both BAFF and APRIL, whereas antioxidant supplementation may also be beneficial in reducing serum levels.