CD4 and Autoimmunity: Of note, PARP-1 deletion leads to suppression of innate immunity by inhibiting NF-κB activation including decrease in TNF and inducible NO synthesis [25], [27], The role of PARP-1 in T cell immune responses remains elusive, as CD4+CD25+Foxp3+ Tregs are instrumental in regulation of immune responses and suppression of autoimmunity, we hypothesized that PARP-1 played a role in the suppressive function of Tregs.