Laminin enhances binding of Toxoplasma gondii tachyzoites to J774 murine macrophage cells

We investigated the effects of the extracellular matrix proteins laminin and fibronectin on the attachment of tachyzoites of Toxoplasma gondii to the murine macrophage cell line J774. Laminin but not fibronectin increased parasite attachment to J774 cells in a dose-dependent fashion. Cyclic YIGSR, a laminin-derived peptide which inhibits laminin binding to the 32/67-kDa laminin-binding protein on host cells, blocked the laminin-mediated enhancement of parasite attachment. An antiserum to the 32/67-kDa laminin- binding protein also inhibited binding of parasites to J774 cells. These results, in conjunction with our previous observations (G. C. Furtado, F. L. Collins, and K. A. Joiner, submitted for publication), demonstrate that tachyzoites bearing surface laminin bind to multiple laminin receptors in attaching to different target cells.