Evaluation of CD4+ CD25+/- CD39+ T-cell populations in peripheral blood of patients following kidney transplantation and during acute allograft rejection.

AIM: Regulatory T cells (Treg) are important in mediating immune tolerance and outcomes of allotransplantation. CD4+ CD25+ CD39+ co-expression identifies memory Treg; CD4+ CD25- CD39+ memory T effectors. We sought to determine CD4+ CD25+/- CD39+ expression from the peripheral blood of patients with end stage renal failure, following transplantation and during episodes of acute cellular rejection. METHODS: CD4+ T cells were isolated from peripheral blood leucocytes and analysed for CD25 and CD39 expression by flow cytometry. Treg suppressive function was measured by suppression of autologous effector T-cell proliferation by Treg in co-culture. RESULTS: CD4+ CD25+/- CD39+ T-cell subsets were tracked longitudinally in the peripheral blood of 17 patients following renal transplantation. Patients with acute T-cell-mediated rejection diagnosed on biopsy had reduced CD4+ CD25+ CD39+ mTreg (P < 0.05) and CD4+ CD25- CD39+ mTeff (P < 0.01) cells compared with non-rejecting patients. CD4+ CD25+ CD39+ mTreg (P < 0.05) and CD4+ CD25- CD39+ mTeff (P = 0.057) were reduced in long-term transplant patients (>1 year) compared with non-immunosuppressed controls. Interestingly, remaining CD4+ CD25+ CD39+ mTreg in the stable transplant patients displayed more potent suppressive capacity compared with non-immunosuppressed controls (83.2% ± 3.1% vs 45.7% ± 8.0%, nTeff:Treg ratio 8:1, P < 0.01). CONCLUSION: CD4+ CD25+ CD39+ mTreg and CD4+ CD25- CD39+ mTeff in peripheral blood can be tracked in renal transplant patients. Acute cellular rejection was accompanied by reduced mTreg and mTeff. Determining changes in these T-cell subsets may help to identify patients with, or at high risk of, renal allograft rejection.

Overexpression of CD39 protects in a mouse model of preeclampsia.

CD39 (NTPDase1), a critical immune and vascular ecto-nucleotidase, hydrolyses pro-inflammatory and pro-thrombotic nucleotides (adenosine-5'-triphosphate (ATP) and adenosine diphosphate) to adenosine. In humans, CD39 is the dominant ecto-nucleotidase in placental trophoblastic tissues and modulates ATP-dependent trophoblastic functions. CD39 is an integral component of regulatory T cells (Treg), which are central to immunological tolerance and maintenance of normal pregnancy. We examined the impact of CD39 overexpression in a mouse model of preeclampsia. Matings were performed between virginal BALB/c female (wild-type (WT) or CD39 transgenic (CD39TG)) and C57BL/6 male mice. On days 10 and 12 of pregnancy BALB/c Th1-polarized cells were injected. Systolic blood pressure (SBP) was measured throughout pregnancy. Mice were sacrificed at day 15 of pregnancy. Following transfer of Th1-polarized cells, SBP of pregnant WT mice increased (118 ± 3 mmHg to 142 ± 5 mmHg). Although ultrastructural changes were evident in the kidney this was not accompanied by significant proteinuria. SBP remained unchanged (115 ± 2 mmHg to 114 ± 3 mmHg) in pregnant CD39TG mice without evidence of renal lesions. We conclude that gestational hypertension can be induced in mice following transfer of maternally derived Th1-polarized cells and that overexpression of CD39 is protective in this model.