As illustrated in Figure 2, the disease (RA)-related epitope peptide moiety (PG70) of the LEAPS conjugate is presented to cognate CD4+ T cells through the engagement of MHC II on the surface of antigen-presenting cells (APC) and the TCR of the T cell while the DerG ICBL modulates the T cell activity through CD4 (48). This evidence concerns the gene CD4 and rheumatoid arthritis.