T cells from induced and spontaneous models of SLE recognize a common T cell epitope on β2-glycoprotein Ⅰ

Systemic lupus erythematosus is a prototypic model for B-cell epitope spread in autoimmunity.Autoantibodies to numerous molecularly distinct self-antigens emerge in a sequential manner over several years,leading to disease manifestations.Among the earliest autoantibodies to appear are those targeting phospholipid-binding proteins,particularlyβ2-glycoprotein Ⅰ.Notably,mice immunized with β2-glycoprotein Ⅰ and lipopolysaccharide develop a strong T cell response to β2-glycoprotein Ⅰ that is associated with autoantibody production and renal disease,similar to that seen in human SLE.Here we hypothesized that mice with murine systemic lupus erythematosus,whether induced or spontaneous,should have T cells that recognizeβ2-glycoprotein I.We evaluated the response of splenic T cells from mice with induced(C57BL/6 and C3H/HeN)and spontaneous(MRL/lpr)systemic lupus erythematosus to peptides spanning the entire sequence of humanβ2GPI.We found that mice with induced and spontaneous systemic lupus erythematosus recognize a common T cell epitope(peptide 31;LYRDTAVFECLPQHAMFG)in domain Ⅲ ofβ2-glycoprotein I.β2GPI-reactive CD4^(+)T cells from the two models differed primarily in cytokine production:T cells from mice with induced SLE expressed IFN-γ,while T cells from MRL/lpr mice expressed both IL-17 and IFN-γ,indicating that IL-17-expressing T cells are not necessary for generating aβ2GPI-reactive T cell response.These data suggest that the generation of aβ2-glycoprotein Ireactive T cell response is shared by both induced and spontaneous models of systemic lupus erythematosus and that this T cell response may mediate epitope spread to autoantibodies in both models.