We thank the Melanoma and Immunology Department members for help and discussion

We thank the Melanoma and Immunology Department members for help and discussion. with the total pool of Tregs being composed therefore of both natural Tregs and newly arising induced peripheral Tregs (1012). Tregs, like other T cells, respond to TCR stimulation and can be induced to expand with cytokines such as IL-2 (13,14). Upon activation Tregs also express costimulatory receptors, such as ICOS and CD28, that further boosts their activation, proliferation, and survival (15). ICOS costimulation of CD4+T cells has been found to facilitate the production of Th2 cytokines such as IL-4, IL-13, and IL-10 (16). Recently, a number of normal tissues have been reported to express ICOS-L and regulate CD4+T-cell activation and cytokine production (1724). In several mouse models of autoimmunity the CD4+CD25+Tregs expressing ICOS were shown to produce IL-10 and control auto-reactive T cells in the invaded organs such as the pre-diabetic pancreas (25,26). Tregs present in melanoma have also been found Rabbit polyclonal to TUBB3 to express ICOS on their surface (27), and ICOS+Tregs have been shown to potently Dodecanoylcarnitine inhibit T-cell responses indirectly through suppressing antigen-presenting cells with IL-10 (26,27). In cancer, the source of ICOS costimulation for Tregs is largely unknown. Although DC, pDC, and B cells can express ICOS-L (16), there are no reports that ICOS-L expressed by tumor cells can regulate CD4+T-cell activation, and the expression of ICOS-L in melanoma has not been characterized yet. In this work, we report that both cultured and freshly-isolated metastatic melanoma cells from Stage IV melanoma patients express ICOS-L on their surface and can co-stimulate Tregs to promote high expression of CD25, Foxp3 and ICOS. == Material and Methods == == Cell lines == L cells transfected with CD32 and ICOS-L were a gift of Yong-Jun Liu. Melanoma tumor cell lines used in the study: WM35, WM35P1N1, WM35P2N1, A684, 888, 938, 624, WM793, WM793P1N1, WM793P2N1, A375, A375S2, 526, 2088, 2089, 2084, A681, A682, A687, 1007, MEMO and SK-MEL-1. == Antibodies == ICOS-L, B7-H1, ICOS, CD86, Foxp3, rat IgG, and hamster IgG isotypes antibodies were from eBioscience (La Jolla, CA). HLA class II, CD4, CD25, CD45RA, CD45, CD8, CD16, IL-10, and IFN- antibodies were from BD Biosciences (San Jose, CA). Anti-MCSP-1 was from Miltenyi Biotec (Auburn, CA). Cytokine analysis by intracellular staining was done with BD fixation/permeabilization kit. == Quantitative real-time RT-PCR == RNA was obtained using PureLink RNA mini-kit (Invitrogen, Carlsbad, Dodecanoylcarnitine CA) and RT was performed using Superscript RT First Strand (Invitrogen). Real-time PCR was then done using a Syber-Green based kit from BioRad (Santa Clara, CA). The primer sequences are: ICOS-L: Forward 5-AGCGTTGAGGTTACAC TGCATGTGGC-3, Reverse 5-GCTGACCACGTCATACAAGCCCCGCA-3; B7-H1: Forward 5-GTCACGGTTCCCAAGGACC-3, Reverse 5-CAGATGACTTCGGCCTT GGG-3; Actin: Forward 5-TTCCTATGTGGGCGACGAGG-3, Reverse 5-ACTCCA TGCCCAGGAAGGAAG-3. == Screening of melanoma cell lines and primary melanomas for B7 molecule expression by flow cytometry == Melanoma cell lines were harvested with protease free dissociation buffer (Invitrogen). Metastatic melanoma tissue was obtained by surgical resection with patient informed consent using clinical and laboratory protocols approved by the M.D. Anderson Cancer Center Institutional Review Board (seeTable 1). Tumor samples were processed within 2 h Dodecanoylcarnitine of resection first by cutting them into 58 mm2pieces followed by mechanical disruption using a Seeward Stomacher (Fisher, Pittsburgh, PA). The cell suspensions were applied over a 70% Ficoll-Isopaque layer in D-PBS. Tumor Dodecanoylcarnitine cells were collected from the gradient interface, washed and stain with antibodies against MCSP1, HLA class II, CD45, and either ICOS-L, B7-H1, or CD86. Before flow cytometry analysis, 7 amino-actinomycin D (7-AAD) was added to the cells. All samples were analyzed using a BD FACScanto II flow cytometer using FACSDiva 5.1 software (BD Biosciences). == Table 1. ==.