Time kinetics of cytokine-secreting cells/10⁵PBMC. PBMC were stimulated in vitro with F(ab′)₂fragments of the autologous (•) or isotypic control (○) monoclonal IgG (10 pg/mL). Number of cells secreting IFN-γ. (A), IL-2 (B), and IL-4 (C) was assessed by ELISPOT. Mean ± SEM (n = 5) for each time point are shown. The numbers of IFN-γ– and IL-2–secreting cells induced by the autologous monoclonal IgG was statistically significantly higher compared with week 0 at different points (*P < .05, **P < .01). At all points of time the numbers of IFN-γ and IL-2, but not IL-4–secreting cells, induced by the autologous IgG were significantly different compared with the isotypic control monoclonal IgG (P < .05). Arrows indicate immunization times.