Open AccessHuman platelet inhibition of Toxoplasma gondii growth
Author(s) -
B. Chumpitazi,
Josiane Simon,
Benoı̂t Polack,
François Peyron,
Stéphane Picot,
Jacques Ricard,
P Ambroise-Thomas
Publication year - 1998
Publication title -
clinical & experimental immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.329
H-Index - 135
eISSN - 1365-2249
pISSN - 0009-9104
DOI - 10.1046/j.1365-2249.1998.00499.x
Subject(s) - toxoplasma gondii , platelet derived growth factor receptor , platelet derived growth factor , biology , growth factor , platelet , intracellular , cyclooxygenase , intracellular parasite , immunology , microbiology and biotechnology , antibody , biochemistry , enzyme , receptor
The human platelet contribution against the intracellular growth of the parasite in vitro in human pulmonary fibroblasts was explored. It was observed that tachyzoites of Toxoplasma gondii induced activation of human platelets and additionally that platelets mediated inhibition of intracellular growth in a virulent T. gondii strain. A prominent role for platelet‐derived growth factor (PDGF) was demonstrated in this phenomenon, by testing human recombinant PDGF‐AA, ‐AB and ‐BB and antibodies to human PDGF‐AB that partially reversed its effects. Moreover, the effect of PDGF was significantly higher if the host cells were treated 2 h before parasite infection. PDGF was not directly ‘toxic’ to free tachyzoites, but only affected parasites within host cells. PDGF‐mediated inhibition may involve the cyclooxygenase cycle of the fibroblasts being partially reversed by the cyclooxygenase inhibitors, acetylsalicylic acid and indomethacin. However, a thromboxane synthetase pathway was not implicated. PDGF action against intracellular tachyzoites may also include increased IL‐6 production in fibroblasts. Finally, transforming growth factor‐beta 1 (TGF‐β1), another component of α‐granules released at the same time as PDGF, may not be antagonistic to the PDGF parasite inhibitory effect in confluent host cells.