CXCR5 and systemic lupus erythematosus: However, according to Jenks and his colleagues, the CXCR5+ subgroup, now known as DN1, is the DN sub-population that expands in elderly healthy individuals,16 while the CXCR5- subgroup constitutes the extrafollicular DN2 subset that is more marked in active SLE.13,17 Furthermore, transcription factor T-bet, whose expression in B cells is considered to be of high importance for the induction of autoimmunity and/or the control of chronic infections,28,29 is expressed (now obviously) in DN2 subset only.13