Regulatory T cells in patients with systemic lupus erythematosus Brenda Alvarado-Sa ´nchez a , Berenice Herna ´ndez-Castro a , Diana Portales-Pe ´rez b , Lourdes Baranda a,c , Esther Layseca-Espinosa a , Carlos Abud-Mendoza c , Ana C. Cubillas-Tejeda b , Roberto Gonza ´lez-Amaro a, * a Departamento de Inmunologı ´a, Facultad de Medicina, UASLP, Ave. V. Carranza 2405, 78210 San Luis Potosı ´, S.L.P., Me ´xico b Laboratorio de Inmunologı ´a Celular y Molecular, Facultad de Ciencias Quı ´micas, UASLP, Ave. Manuel Nava s/n, 78210 San Luis Potosı ´, S.L.P., Me ´xico c Unidad Regional de Reumatologı ´a y Osteoporosis, Hospital Central Dr. Ignacio Morones Prieto, Ave. V. Carranza 2395, 78210 San Luis Potosı ´, S.L.P., Me ´xico Received 1 February 2006; revised 5 June 2006; accepted 5 June 2006 Abstract Regulatory T cells have an important role in the control of self-reactivity, and in the pathogenesis of autoimmune inflammatory conditions. The aim of this work was to perform a quantitative and functional analysis of regulatory T cells in patients with systemic lupus erythematosus (SLE). We studied twenty-three patients with SLE (19 active, 4 inactive), and twenty-seven healthy subjects as well as fifteen patients with rheu- matoid arthritis (RA). The following cell subsets were analyzed in peripheral blood mononuclear cells by flow cytometry: CD4þCD25þ, CD4þCD25 bright , CD4þFoxp3þ (Treg cells), CD8þCD28 (Ts cells), CD4þIL-10þ (Tr1 cells), and CD4þTGF-bþ (Th3 cells). In addition, the in vitro suppressive activity of CD4þCD25þ lymphocytes was tested. We found no significant differences in the levels of all regulatory cell subsets studied in SLE patients compared to controls and RA patients. However, a defective regulatory function of CD4þCD25þT cells was observed in a significant fraction (31%) of patients with SLE. Our data indicate that although approximately one third of patients with SLE show an abnormal immunosuppressive function of Treg lym- phocytes, their levels of the different regulatory T cell subsets in peripheral blood are not significantly different from those found in controls. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Autoimmune diseases; Systemic lupus erythematosus; Treg lymphocytes; Suppressor cells 1. Introduction Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the deposition of immune complexes with an inflammatory/necrotic phenomenon in different tissues, mainly kidney, skin, blood vessels, and central nervous system [1]. Multiple immune abnormalities are characteristic of this condition, including the synthesis of different auto- antibodies, B cell hyperactivity, increased rate of lymphoid cell apoptosis, and an enhanced synthesis of IL-10 [2,3]. In ad- dition, T cells from these patients show a diminished in vitro response to different stimuli as well as abnormalities in early cell activation events, and a defective production and response to IL-2 [4,5]. Finally, early works suggested that SLE patients have a defective function of regulatory T cells [6]. The existence of a T lymphocyte subset with suppressor activity was initially proposed by Gershon and Kondo [7]. Several years later, it was described that these suppressor cells are CD8þ and that they have an important role in immune regulation [8]. These suppressor lymphocytes or Ts cells are Abbreviations: SLE, systemic lupus erythematosus; Ts, T suppressor cells; T REG cells, regulatory T cells; Tr1 cells, type-1 regulatory T cells; RA, rheu- matoid arthritis. * Corresponding author. Tel./fax: þ52 444 817 7706. E-mail address: rgonzale@uaslp.mx (R. Gonza ´lez-Amaro). 0896-8411/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jaut.2006.06.005 Journal of Autoimmunity 27 (2006) 110e118 www.elsevier.com/locate/issn/08968411