mAb against hen egg-white lysozyme regulate its presentation to CD4(+) T cells

Specific antibodies increase antigen uptake and presentation by antigen-pre senting cells via the B cell receptor in a cells or Fc gamma R in dendritic cells,To determine whether the interaction between antibody and antigen co uld influence the set of peptides presented by MHC II molecules, we analyze d the presentation of different CD4(+) T cell epitopes of hen egg-white lys ozyme (HEL) after the capture of immune complexes formed between HEL and se ven different specific mAb, The 103-117 T cell epitope (I-E-d) was specific ally and selectively up-regulated by the D1.3 and F9.13.7 mAb that binds to proximal loops in the native structure of HEL. Furthermore, II-independent T cell epitopes exposed on the HEL surface (116-129 and 34-45, I-A(k) rest ricted) which require a mild processing involving the recycling of MHC II m olecules were selectively up-regulated by mAb that overlap those T cell epi topes (D1.3 and D44.1), However, F10.6.6, somatically derived from the same germ line genes as D44.1 and exhibiting an higher affinity for HEL, was wi thout effect on the presentation of the 34-45 epitope, An II-dependent T ce ll epitope buried into the tertiary structure of HEL (45-61, I-A(k) restric ted) and requiring the neosynthesis of MHC II was up-regulated by high-affi nity mAb recognizing epitopes located at the N- or C-terminus of the T cell epitope, These results strongly suggest that (i) the spatial relationship linking the T cell epitope and the B cell epitope recognized by the mAb, (i i) the intrinsic processing requirements of the T cell epitope, and (iii) t he antibody affinity influences the presentation of a given T cell epitope.