CD4 and systemic lupus erythematosus: Iwata et al. (63) found that in the MRL-Faslpr lupus mouse model, CD11b+Gr-1low cells inhibited the proliferation of CD4+ T cells through Arg-1, and the percentage of CD11b+Gr-1low cells was increased in the spleen, kidneys, and blood of 10-week-old lupus mice, suggesting that these cells contribute to immune regulation.