Role of Interferon-gamma against Invasion by Toxoplasma gondii in a Human Monocytic Cell Line (THP1): Involvement of the Parasite's Secretory Phospholipase A2

Author： Marin J.E.G. Bonhomme A. Guenounou M. Pinon J.M.

Publisher： Academic Press

ISSN： 0008-8749

Source： Cellular Immunology, Vol.169, Iss.2, 1996-05, pp. : 218-225

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Abstract

We examined the role of IFNgamma in protection against Toxoplasma gondii in the monocytoid cell line THP1. The addition of IFNgamma to cultured infected THP1 cells reduced the number of parasited cells without altering intracellular multiplication during the first 24 hr. This reduction was potentiated by bacterial lipopolysaccharide (LPS). We also examined the role of an enzyme important for T. gondii cellular invasion, secretory phospholipase-A2 (sPLA2) and its relation with IFNgamma-induced protection. Treatment of cells or parasites with a specific inhibitor of sPLA2 significantly reduced the number of infected cells at 6 hr. The addition of exogenous sPLA2 from Naja naja venom did not interfere with the protective effect of IFNgamma and confered protection when used alone. PLA2 activity was measured in supernatants of parasites maintained in the presence of IFNgamma, and the results suggested that IFNgamma opposes cell invasion by T. gondii by suppressing parasite production of PLA2.