B-CLL cells (18 patients) were cultured at 2 × 10⁶/mL for 48 hours with 10 μg/mL of anti-CD23 MoAb or mouse IgG1 (isotype-matched control), in the presence or absence of L-NAME (1 mmol/L). Cell-free supernatants were collected and analyzed for their nitrite content by the Griess colorimetric reaction. Results, expressed as percentages of the production in control cultures performed with medium alone, were analyzed by Student's t-test using the Statview software. P values refer to the comparison of the various groups with the control medium.

Abbreviation: NS, not significant.