Society of Diabetic Nephropathy Prevention Journal of Nephropathology 2251-8363 5 3 2016 07 01 Value of Foxp3 expressing T-regulatory cells in renal tissue in lupus nephritis; an immunohistochemical study 105 110 10.15171/jnp.2016.19 EN Marwa M Shakweer Maha Behairy Nadia G Elhefnawy Tamer W Elsaid Journal Article 10.15171/jnp.2016.19 Background: Forkhead box P3 (Foxp3) functions as a master regulator in the development and function of T-regulatory (Treg) cells. Recent studies have shown that autoimmune diseases including systemic lupus erythematosus (SLE) are associated with an imbalance with the Treg cells and T helper (Th) subtypes. Objectives: To evaluate immunohistochemical expression of Foxp3 positive Treg cells in lupus nephritis (LN) and analyze its association with clinicopathologic parameters. Materials and Methods: Renal biopsy specimens of 50 patients with LN were studied. Specimens were divided into; group A; 25 LN cases without proliferative activity (Class II and V) and group B: 25 cases with proliferative activity (Class III and IV). Immunohistochemical staining for anti-human Foxp3 antibody and grading from grade 0 to grade 3 was done. Results: Foxp3 expression in group A was (grade 0 in 14 [56.0%], grade +1 in 11 [44.0 %]) in comparison to group B (grade +1 in 6 [24.0%], grade +2 in 11 [44.0%] and grade +3 in 8 [32.0%]) (P < 0.001). Foxp3 expression was significantly correlated to National Institutes of Health (NIH) activity and chronicity indices (P < 0.05), as well as serum creatinine (P < 0.01) in both groups A and B and there was a highly significant correlation with proteinuria (P < 0.01) in group B with proliferative LN. Conclusions: Immunohistochemical Foxp3 expression in renal tissue was higher in proliferative versus non-proliferative LN and is associated with activity and severity of LN. Further studies are needed to determine its prognostic value in LN.