FIG 6.

AgSAP interacts with mammalian cell surface proteoglycan and decreases the immune response. AgSAP binds to heparan sulfate, which is present on the host cell surface. (A) In an ELISA, we assessed AgSAP binding to heparan sulfate. As a control, we used mosGILT, another A. gambiae salivary protein present. (B) To investigate the AgSAP interaction with heparan sulfate proteoglycans present on the mammalian cell surface, we used an immortalized T lymphocyte cell line (Jurkat). The overlay histogram shows AgSAP (red) and two other proteins, mosGILT (green) and PGLYRP1 (blue), binding to Jurkat cells. (C) Jurkat Lucia NFAT reporter cells were coincubated with AgSAP or heat-inactivated AgSAP and then stimulated with phorbol myristate acetate-ionomycin. The activity was measured using a CellTiter-Glo assay, and the relative luminescence values were compared. (D) The effect on the Jurkat cell response was also measured at the RNA level by comparing the expression levels of TNF-α.