Serum levels of sCD100 and titers of antibodies in mice immunized with a TD Ag.

C57BL/6 mice (6-8 weeks old) were immunized intraperitoneally with 100 μg of NP-CGG as an alum precipitated complex (n = 5) at day 0, boosted at day 21 (arrowheads), and bled at the indicated days. Concentrations of sCD100 (A) and serum titers of anti-NP antibodies (B) were determined by ELISA. The concentrations of anti-NP IgG1 antibodies were established by comparison with standard curves created from pooled sera of C57BL/6 mice 28 days after immunization. The concentration of anti-NP IgG1 present in a 1:1000 dilution of pooled immune sera of C57BL/6 mice was defined as one arbitrary unit.18