Figure 1. PPS14 and autologous MSA co-attached to latex beads induce PPS14-specific antibody responses in a T cell-dependent manner.

(A) BALB/c and BALB/c athymic nude mice (n=7), were immunized on days 0 and 14 (arrows) with ≈ 2×10⁸ latex beads, coated with PPS14 combined with glycine or MSA, in alum+CpG-ODN. Each dose of the corresponding beads was adjusted to contain approximately 230ng of serologically active PPS14. (B) Female BALB/c mice (n=5) were injected with 1mg of anti-CD4 mAb (GK1.5) or polyclonal rat IgG2b (control), 32h before injection with 1µg of free PPS14, or 2.2 × 10⁸ PPS14+[MSA]-beads containing 80ng of PPS14, both admixed only with CpG-ODN. Mice received a secondary immunization 14 days later with the same antigen in the absence of anti-CD4 mAb or polyclonal rat IgG. Anti-MSA IgM responses are only shown for Panel A. Panel A and B shown different experiments using different bead preparations. Beads were always washed in PBS prior to immunization, to remove any antigen leaked free to the supernatant. Serum titers of IgG and IgM specific for PPS14 and MSA were determined by ELISA. Values are expressed as geometric mean ± SEM. *p < 0.05 (BALB/c versus athymic nude mice or controls relative to GK1.5 treated mice), #p< 0.05 (titer⁻¹ relative to the previous bleeding of each mouse group); Student's t-test.