CVF enhances NK cell CD54 up-regulation in the presence of complement and rituximab-coated target cells. PBMCs and Raji cells were mixed at a 1:1 ratio for 20 hours in the presence of 50% serum, pleural fluid, or ascites with or without the addition of CVF in various concentrations of rituximab. NK cell–surface marker expression was determined by using flow cytometry with gating on CD3⁻CD56⁺ lymphocytes. (A) NK cell CD54, expressed as a percentage of CD54^bright, after culture in serum or serum plus CVF (n = 3 samples per group). (B) NK cell CD54, expressed as a percentage of CD54 bright, after culture in pleural fluid or pleural fluid plus CVF (n = 3 samples per group). (C) NK cell CD54, expressed as a percentage of CD54 bright, after culture in ascites or ascites plus CVF (n = 3 samples per group). Error bars represent SD of the mean.