CD3 ξ defects in systemic lupus erythematosus

The prototype autoimmune disease, systemic lupus erythematosus (SLE), has been known to be associated with deficiency of ξ chain, a component of the T-cell receptor-CD3 complex. Comprehensive analysis has shown that expression of the CD3 ξ chain is attenuated or absent in over half of SLE patients. Furthermore, aberrant transcripts of the CD3 ξ chain, including spliced variants lacking exon 7 or having a short 3′-untranslated region, have been detected in SLE T cells. Although attenuated expression of the CD3 ξ chain is also observed in cancer patients, infections and other autoimmune diseases, sustained attenuation of the CD3 ξ expression accompanied with aberrant transcripts are only observed in SLE. In this study, the authors review the unique features of CD3 ξ defects observed in SLE and discuss the molecular basis of the defects by recent findings in animal models, single-nucleotide polymorphisms and genome-wide association studies.