Inhibitory effect of mAb 5H2 on platelet aggregation induced byS agalactiae6313. Fifty microliters of S agalactiae cells (5 × 10⁷) were preincubated with 5 μg mAb 5H2 or an equal concentration of isotype-matched control mAb 2B8 and then tested for their ability to activate platelet aggregation in PRP (0.4 mL) as reported in “Materials and methods.” The data are representative of 3 experiments.