Kinetics of intracellular Ca²⁺ changes in BL cells treated by various ligands of CD77 antigen. CD77⁺ Ramos cells were stimulated by 38.13 anti-CD77 MoAb (10 μg/mL), 5B5 anti-CD77 MoAb (10 μg/mL), VT-B (5 ng/mL), or by HJ6 anti-Gb4 MoAb (10 μg/mL). CD77⁻ Namalwa cells were stimulated by 38.13 anti-CD77 MoAb (10 μg/mL). Ramos cells were also incubated with 2.5 mmol/L EGTA or 25 μg/mL Verapamil before stimulation by 38.13 MoAb. Intracellular Ca²⁺ was measured using indo-1 indicator. Results are representative of six different experiments. The basal [Ca²⁺]i, before addition of 38.13 MoAb, was 230 ± 50 nmol/L (mean ± SD, 50 cells) and the [Ca²⁺]i rise can reach a peak of 540 ± 30 nmol/L.