Modulator of intracellular Ca(2+), thapsigargin, interferes with in vitro secretion of cytokines and nitric oxide.

Interference of thapsigargin (TG), an inhibitor of endoplasmic reticulum Ca(2+) ATPase, with immune reactivity of murine macrophages was investigated under conditions in vitro. The activation of cells with lipopolysaccharide (LPS), interferon-(gamma) (IFN-(gamma)), and with acyclic nucleoside phosphonate N(6)-isobutyl-9-[2-(phosphonomethoxy)ethyl]- 2,6-diaminopurine (N(6)-isobutyl-PMEDAP) resulted in enhanced production of cytokines TNF-alpha, IL-10, chemokines RANTES/CCL5 and MIP-1alpha/CCL3, as well as in substantially augmented production of nitric oxide (NO) triggered by IFN-(gamma). The effects were in a dual mode of action influenced by TG (1 microM). While TG upregulated secretion of TNF-alpha, it inhibited secretion of IL-10 and RANTES. The immune-stimulated secretion of MIP-1alpha remained virtually unaffected, though TG on its own activated expression of MIP-1alpha in macrophages. The high-output NO production induced by IFN-(gamma), high concentrations of LPS, or by combination of IFN-(gamma) plus LPS or N(6)-isobutyl-PMEDAP was inhibited by TG. On the other hand, production of NO which was marginally activated by low concentration of LPS was upregulated by TG.