Trinactin is a member of the macrotetrolide complex produced by a range of Streptomyces sp.. Early literature reported that trinactin is a monovalent cation ionophore with high selectivity for ammonium and potassium. Trinactin inhibits T-cell proliferation induced by IL-2, and cytokine production at nanomolar levels for IL-2, IL-4, IL-5 and interferon-γ. Trinactin has not previously been available for intensive investigation.