Three studies analyzed systemic immune responses using stimulation of whole blood or PBMCs with LPS, a Toll-like receptor 4 agonist with an important role in regulation of immune responses to infection, or phorbol 12-myristate 13-acetate (PMA) and ionomycin [5,9,21] to induce cytokine responses in T cells. The gene discussed is TLR4; the disease is infection.