In addition, LAG-3 is a negative regulator of T cell receptor (TCR)-mediated signal transduction in effector

T cells and functions in the same manner as cytotoxic T lymphocyte antigen-4 (CTLA-4) [9–12]. Finally, LAG-3 controls activated regulatory T cells (Tregs), while it is not expressed by unstimulated natural Tregs[13]. However, LAG-3 is expressed by interleukin Selleck LDK378 (IL)-10-secreting early growth response (Egr)-2+LAG-3+CD4+ Tregs associated with Peyer’s patches [14]. We have shown previously that depleting anti-LAG-3 antibodies prevented the development of alloreactive effector T cells in a heart allotransplant model in rodents and represents an effective treatment for allograft rejection [15]. In this study, we have characterized a cytotoxic anti-LAG-3 chimeric antibody (chimeric A9H12) and evaluated its potential for selective therapeutic depletion in a non-human primate model of delayed-type hypersensitivity (DTH), a low-invasive HIF inhibitor and non-terminal model based on the induction of local T helper type 1 (Th-1)-mediated cellular immune responses [16]. Our investigation demonstrated

that LAG-3+ T lymphocytes could be depleted in vivo in primates and that this resulted in a long-lasting inhibition of immune responses in this preclinical model. C57/B6 mice were immunized three times with Chinese hamster ovary (CHO) cells transfected with human LAG-3 cDNA, followed by an intravenous (i.v.) booster injection of a recombinant hLAG-3Ig protein purified from the supernatant of transfected CHO cells. Three Megestrol Acetate days after the boost, splenocytes were fused with the X63.AG8653 fusion partner [17] to obtain hybridoma cells, using traditional techniques. The A9H12 hybridoma was selected for its antibody-dependent cell cytotoxicity (ADCC) activity towards LAG-3 expressing cells and subcloned to yield a stable cell line. A bicistronic vector coding for the variable heavy (VH) and variable light (VL) domains of A9H12 fused to human CL kappa and CH1-hinge-CH2-CH3 immunlglobulin (Ig)G1 regions was

generated and used to transfect CHO-S cells (Invitrogen, Illkirch, France). After antibiotic selection and limiting dilutions, a stable subclone was selected to produce the chimeric A9H12 in ProCHO5 medium (Lonza, Vervier, Belgium). The product in the supernatant cell was purified by adsorption on a HiTrap recombinant Protein A FF column (GE Healthcare, Velizy, France), eluted by acid pH (Glycin HCl, 0·1 M, pH 2·8) and dialysed against phosphate-buffered saline (PBS; Invitrogen). LAG-3+ CHO cells or human peripheral blood mononuclear cells (PBMCs) stimulated with 1 µg/ml of Staphylococcal enterotoxin B (SEB; Sigma Aldrich, L’Isle D’Abeau Chesnes, France) for 48 h were used as targets. Chimeric A9H12 binding was revealed with a fluorescein isothiocyanate (FITC)-conjugated goat F(ab′)2 anti-human IgG (Southern Biotech, Birmingham, AL, USA).