Figure 1.

Model to evaluate the ability of transgenic KJ⁺ CD4⁺ T cells to provide help for memory B cells. (a) Naive KJ⁺ CD4⁺ T cells help primed B cells but not naive B cells following sol-OVA challenge. SCID recipients were injected with 3 × 10⁵ naive KJ⁺ CD4⁺ T cells together with 10⁷ primed B cells or 10⁷ naive B cells or with 10⁷ primed B cells alone as a control. Mice were challenged i.p. with 10 μg sol-OVA immediately after transfer and anti-OVA antibody levels were measured on day 14. The values represent the geometric means + SD of six recipients per group. (b) The effect of antigen dose on antibody production by primed B cells. SCID recipients received 10⁷ primed B cells alone (con), or together with 3 × 10⁵ naive KJ⁺ CD4⁺ T cells, and were challenged i.p. with 10 μg or 100 μg sol-OVA. The values shown represent the geometric means + SD of five or two (control) recipients per group. (c) Titration of primed B cells. SCID recipients were injected with 3 × 10⁶, 10⁷ or 3 × 10⁷ primed B cells together with 3 × 10⁶ KJ⁺ CD4⁺ T cells; mice were challenged i.p. with 10 μg sol-OVA immediately after transfer and bled 14 days later. The values represent the geometric means + SD of six recipients per group.