The determination of the frequencies of predicted citrullinated peptide-specific CD4+ T cells in RA patients (ideally with different disease severity scores versus healthy controls) using MHC II tetramers along with the characterization of the phenotypic (i. e., memory, naïve, Treg CD4+ T cells) and functional (i. e., cytokine profile produced upon antigen stimulation) nature of the responding T cell repertoire will help to further highlight the relevance of this methodology in regard to RA pathogenesis [16–18, 35]. This evidence concerns the gene CD4 and rheumatoid arthritis.