Requirement of CD28-CD86 co-stimulation in the interaction between antigen-primed T helper type 2 and B cells

The interaction between CD28 and its ligands, CD80 and CD86, is crucial for an optimal activation of antigen-specific T cells, However, the requirement of CD80 or CD86 co-stimulation in T(h)2 cell differentiation and activation is controversial. Freshly isolated murine CD4(+) and CD8(+) T cells were incubated with P815 transfectants expressing a similar level of either CD80 or CD86 in the presence of anti-CD3 mAb. Both CD80 and CD86 co-stimulated the proliferation of CD4(+) and CD8(+) T cells at comparable time-kinetics and magnitude, but CD86 alone was able to co-stimulate IL-4 and especially IL-10 production in CD4(+) T cells. In typical T(h)2-dependent immune responses elicited by Nippostrongylus brasiliensis infection, the anti-CD86 mAb treatment but not the anti-CD80 mAb treatment efficiently inhibited antigen-specific IgE and IgG1 production, which was accompanied with the reduced IL-4 production. Our results suggest that CD86 co-stimulation plays a dominant role not only in the primary activation of T(h)2 cells but also in the secondary interaction between antigen-primed T(h)2 cells and B cells.