CD4+ CD52lo T-cell expression contributes to the development of systemic lupus erythematosus

The cell-surface glycoprotein CD52 is widely expressed in lymphocytes. CD4+ CD52hi T cells are functioning suppressor CD4+ T cells. We investigated the role of the immune regulation of CD4+ CD52 T cells in systemic lupus erythematosus (SLE). CD4+ CD52lo T cells were increased in SLE patients, in positive correlation with SLEDAI, anti-ds-DNA antibody, and IgG concentration. Circulating follicular helper-like T cells (Tfh-like cells) were also increased in SLE, in positive correlation with CD4+ CD52lo T cells. Chemokine receptor 8 (CCR8) expression in CD4+ CD52lo T cells was increased. In vitro experiments using CD4 T cells of SLE patients showed that thymus and activation-regulated chemokine (TARC), a ligand of CCR8, contributed to the development of CD4+ CD52hi T cells into CD4+ CD52lo T cells. Our findings suggest that CD4 + CD52lo T-cell upregulation is involved in the production of pathogens by autoantibodies, and TARC may contribute to the development of SLE through an aberrant induction of CD4+ CD52lo T cells.