Inhibition of merozoite invasion using anti–RSP-2 mAbs. A suspension of synchronized mature IEs of the adhesion phenotypes CSA, CD36, and ICAM-1 in 200 μL/well at a final hematocrit of 2% in culture medium were incubated in 96-well flat-bottom plates together with 10 μL mAbs B4 (A) and D10 (B) at different concentrations. Four hours after invasion 100 μCi (3.7 MBq) of ³H-hypoxanthine was added and the incorporated radioactivity counted 24 hours later. The percentage (±SD) of inhibition was calculated using the t test by comparing the count-per-minute values of controls with those obtained in the presence of mAbs.