CD 39 is involved in mediating suppression by M ycobacterium bovis BCG -activated human CD 8 super(+) CD 39 super(+) regulatory T cells

Regulatory T ( T reg) cells can balance normal tissue homeostasis by limiting inflammatory tissue damage, e.g. during pathogen infection, but on the other hand can also limit protective immunity induced during natural infection or following vaccination. Because most studies have focused on the role of CD 4 super(+) T reg cells, relatively little is known about the phenotype and function of CD 8 super(+) T reg cells, particularly in infectious diseases. Here, we describe for the first time the expression of CD 39 ( E-NTPD ase1) on Mycobacterium-activated human CD 8 super(+) T cells. These CD 8 super(+) CD 39 super(+) T cells significantly co-expressed the T reg markers CD 25, F oxp3, lymphocyte activation gene-3 (LAG-3), and CC chemokine ligand 4 (CCL4), and suppressed the proliferative response of antigen-specific CD 4 super(+) T helper-1 (Th1) cells. Pharmacological or antibody mediated blocking of CD 39 function resulted in partial reversal of suppression. These data identify CD 39 as a novel marker of human regulatory CD 8 super(+) T cells and indicate that CD 39 is functionally involved in suppression by CD 8 super(+) T reg cells.