FIG. 4.

Effect of costimulation of T cells with bacteria and CEACAM-binding proteins on proliferation of CD4⁺ T cells. CD4⁺ T cells were prestimulated with IL-2 for 48 h. After being washed, the cells were incubated with the antibody A0115 (50 μg/ml; A and B) or the recombinant polypeptide rD-7 (2 μg/ml; C and D) for 1 h before the addition of a live Opa⁺ or Opa⁻ N. meningitidis (Nm) variant of strain C751 in the presence of anti-sCD3 antibody at 1 μg/ml. The results shown in panels C and D are % changes in proliferation relative to that in control cells and were calculated using average values for [³H]thymidine incorporation from duplicate samples. Ng, N. gonorrhoeae.