In addition, we provide further evidence that Treg are indeed involved in the suppression of specific CD4+ T cell responses against autoantigens in murine lupus, as the depletion of CD25+ Treg, either in vitro before re-stimulation with the autoantigen or in vivo before the immunization against the autoantigen, led to an increase in the frequencies of detectable auto-antigen-specific CD4+ T cells by approximately 50%. Here, CD4 is linked to systemic lupus erythematosus.