CD247 and systemic lupus erythematosus: Meanwhile, expression of cluster differentiation (CD) 3ζ (i.e., a molecule in the T cell receptor [TCR] complex and CD3 that plays a role in regulating the influx of calcium into T cells) is significantly decreased in SLE (Figure 2), causing a rearrangement of the TCR-CD3 complex, where CD3ζ is substituted by the homologous Fc receptor common gamma subunit chain (FcRγ).