CSB enhances cell aggregation in PBMC cultures. The effect of (A) control, (B) CSB (1 mg/mL), (C) PHA (1 μg/mL), and (D) HA (10 μg/mL) on PBMC aggregation is shown. PBMC were cultured in 24-well plates for 24 hours, and the cultures were then examined by phase microscopy using a Nikon Phase Contrast ELWD 0.3 microscope (original magnification × 100).