Antigenic Peptide-Thioredoxin Fusion Chimeras for In Vitro Stimulus of CD4⁺ TCR⁺ Jurkat T Cells

Study of CD4⁺ T cell response and T cell receptor (TCR) specificity is crucial for understanding etiology of immune-mediated diseases and developing targeted therapies. However, solubility, accessibility, and stability of synthetic antigenic peptides used in T cell assays may be a critical point in such studies. Here we present a T cell activation reporter system using recombinant proteins containing antigenic epitopes fused with bacterial thioredoxin (trx-peptides) and obtained by bacterial expression. We report that co-incubation of CD4⁺ HA1.7 TCR⁺ reporter Jurkat 76 TRP cells with CD80⁺ HLA-DRB1*01:01⁺ HeLa cells or CD4⁺ Ob.1A12 TCR⁺ Jurkat 76 TRP with CD80⁺ HLA-DRB1*15:01⁺ HeLa cells resulted in activation of reporter Jurkat 76 TPR after addition of recombinant trx-peptide fusion proteins, containing TCR-specific epitopes. Trx-peptides were comparable with corresponding synthetic peptides in their capacity to activate Jurkat 76 TPR. These data demonstrate that thioredoxin as a carrier protein (trx) for antigenic peptides exhibits minimal interference with recognition of MHC-specific peptides by TCRs and consequent T cell activation. Our findings highlight potential feasibility of trx-peptides as a reagent for assessing the immunogenicity of antigenic fragments.