In order to better characterize the molecular mechanisms of CD28-mediated IL-17A expression, we performed a detailed kinetic analysis of IL-17A gene expression and secretion by stimulating human CD4+ T cells from HD with an agonistic anti-CD28 Ab (CD28.2) that has been described to bind the same epitope recognized by B7 molecules (48). The gene discussed is CD28; the disease is Huntington disease.