IL21 and Autoimmunity: Patients developing autoimmunity showed, compared to those who did not, reduced thymopoiesis at month 12 (51), and higher rates of T cell cycling, with increased proliferation and apoptosis but without differences in lymphopenia between groups (41) Occurrence of autoimmunity was associated with increased production of IL-21 in one study, possibly driven by a genetical susceptibility (41).