B-CD8+ T Cell Interactions in the Anti-Idiotypic Response against a Self-Antibody

Abstract EN

P3 is a murine, germline, IgM mAb that recognizes N-glycolylated gangliosides and other self-antigens.

This antibody is able to induce an anti-idiotypic IgG response and B-T idiotypic cascade, even in the absence of any adjuvant or carrier protein.

P3 mAb immunization induces the expression of activation markers in a significant percentage of B-1a cells in vivo.

Interestingly, transfer of both B-1a and B-2 to BALB/Xid mice was required to recover anti-P3 IgG response in this model.

In fact, P3 mAb activated B-2 cells, in vitro, inducing secretion of IFN-γ and IL-4, although this activation was not detected ex vivo.

Interestingly, naïve CD8+ T cells increased the expression of activation markers and IFN-γ secretion in the presence of B-1a cells isolated from P3 mAb-immunized mice, even without in vitro restimulation.

In contrast, B-2 cells were able to stimulate CD8+ T cells only if P3 was added in vitro.

Using bioinformatics, a MHC class I-binding peptide from P3 VH region was identified.

P3 mAb was able to induce a specific CTL response in vivo against cells presenting this peptide.

Both humoral and CTL anti-idiotypic responses could be mechanisms to protect against the self-reactive antibody, contributing to keeping the tolerance to self-antigens.