IntroductionProgrammed death-1 (PD-1), a member of the CD28 costimulatory receptor superfamily, inhibits T-cell activity by providing a second signal to T cells in conjunction with signaling through the T-cell receptor. 1 To date, B7-H1 and B7-DC have been identified as ligands for PD-1 (PD-Ls). During chronic viral infection, PD-1 is selectively up-regulated by the exhausted T cells, and blockade of this pathway restores CD8 ϩ T-cell function and reduces viral load. 2 This signaling system has been recently highlighted in the research of human immunodeficiency virus (HIV) infection. [3][4][5][6] In addition, PD-1 is indicated to be involved in the evasion of tumor immunity. [7][8][9][10] Hodgkin lymphoma (HL) is characterized by massive reactive infiltrates surrounding Hodgkin/Reed-Sternberg (H/RS) cells. HL patients are well recognized as having defective cellular immunity; they are susceptible to bacterial, fungal, and viral infections, and in vitro studies show depressed T-cell proliferation and reduced synthesis of Th1 cytokines. 11 We report here that PD-1-PD-L signaling system is operative in patients with HL, and tumor-infiltrating T cells around H/RS cells seem to be kept in balance by this inhibitory signaling. Our findings illuminate the mechanism for deficient cellular immunity observed in HL patients, and propose a potentially effective immunologic strategy for the treatment of HL. Methods Cell lines and clinical sample preparationThe following cell lines were described previously 12,13 : HL cell lines KM-H2, L428, and HDLM-2; anaplastic large cell lymphoma (ALCL) cell line DEL; follicular lymphoma cell line FL-218; diffuse large B-cell lymphoma (DLBCL) cell line KIS-1; Burkitt lymphoma cell lines Daudi, Raji, Middle 91, Tree 92, and Ramos; adult T-cell leukemia/lymphoma cell line HUT 102; and acute T-cell leukemia cell line Jurkat. LCL-OHN is an Epstein-Barr virus (EBV)-transformed lymphoblastoid B-cell line (LCL). Peripheral blood samples were collected from 19 HL patients, 12 B-NHL patients, and 11 healthy volunteers after informed consent was obtained in accordance with the Declaration of Helsinki. This study is approved by the institutional review board of Kyoto University. After removing red blood cells using ACK lysis buffer, leukocytes were subjected to flow cytometry. For immunohistochemistry, tissue specimens were snap-frozen in OCT compound (TissueTek, Tokyo, Japan) and stored at Ϫ80°C. Reverse transcription-polymerase chain reaction, flow cytometry, and immunohistochemistryTotal RNA was isolated from cells with Trizol (Invitrogen, Carlsbad, CA), and cDNA was synthesized using MultiScribe Reverse Transcriptase (Applied Biosystems, Foster City, CA). PCR assays were performed by the conventional method using Taq polymerase (TaKaRa Biotechnology, Shiga, Japan). For flow cytometry, cells were analyzed on a FACScan (Becton Dickinson, Mansfield, MS). The following antibodies were used: PEconjugated B7-H1 and B7-DC (eBioscience, San Diego, CA), FITC-PD-1 (BD Pharmingen, San Diego, CA), PC5-CD4 a...

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BackgroundDe novo CD5-positive diffuse large B-cell lymphoma (CD5 + DLBCL) is clinicopathologically and genetically distinct from CD5-negative (CD5

B7-H1 is a member of the B7 family that inhibits the function of T-cells through its receptor programmed death-1 (PD-1). We examined B7-H1 expression in anaplastic large cell lymphoma (ALCL) and Hodgkin lymphoma (HL) and found that it was constitutively expressed in both clinical samples and cell lines. In anaplastic lymphoma kinase-positive (ALK + ) ALCL cells, B7-H1 expression was suppressed by the blocking of extracellular signal-regulated kinase (ERK) signaling and upregulated by the augmentation of ERK activity by phorbol 13-myristate 12-acetate stimulation, suggesting that B7-H1 expression is regulated by ERK signaling pathway in ALCL. ERK is one of the downstream mediators of nucleophosmin (NPM)/ALK signaling in ALK + ALCL, and pharmacological inhibition of ALK was shown to dephosphorylate ERK and downregulate B7-H1. The involvement of NPM /ALK in B7-H1 expression was also demonstrated by introducing the construct into human non-ALCL lymphoid cell lines, which resulted in B7-H1 expression. In the case of HL, B7-H1 expression was shown to be dependent on the ERK and p38 mitogen-activated protein kinase (MAPK) signaling pathways. These results suggest that B7-H1 expression is controlled by common ERK signaling pathways in ALCL and HL cells. Our findings provide a potentially effective immunotherapeutic strategy for these B7-H1-expressing tumors. (Cancer Sci 2009; 100: 2093-2100) P rogrammed death-1 (PD-1) is a member of the CD28 costimulatory receptor superfamily that inhibits T-cell activity by providing a second signal to T-cells in conjunction with signaling via the T-cell receptor.(1,2) One of its ligands B7-H1, which is also known as PD-L1 or CD274, is reported to be expressed on a variety of malignancies, including breast, lung, colon, and ovarian cancers.(3) Its expression is associated with poor prognosis in some of these diseases.(4,5) Several studies using mouse models have indicated that PD-1 ⁄ B7-H1 signaling plays a pivotal role in the immune escape of tumors. Subcutaneously injected B7-H1-expressing tumor cells grow in wild-type mice but are eliminated in PD-1 knockout mice.(6) In addition, B7-H1 expression on tumor cells increases the apoptosis of tumor-reactive T-cells.(7) However, little is known about the regulatory mechanisms of B7-H1 expression in these malignant cells.Hodgkin lymphoma (HL) is characterized by massive reactive infiltrates surrounding Hodgkin ⁄ Reed-Sternberg (H ⁄ RS) cells, and H ⁄ RS cells represent only about 1% of cells in tumor tissues. We previously reported B7-H1 expression in H ⁄ RS cells and PD-1 expression in tumor-infiltrating T-cells and that the antitumor activity of T-cells was restored by blocking the PD-1 ⁄ B7-H1 signaling pathway. (8) Anaplastic large cell lymphoma (ALCL) is a subtype of T-cell lymphoma characterized by a proliferation of CD30-positive large tumor cells with abundant cytoplasm and pleomorphic nuclei. ALCL is sometimes accompanied by variable amounts of reactive cells, and the clinical and pathological features of ALCL often resemble those...

Our data demonstrate that patients in the EBVMCU, a specific clinical subgroup of MTX-LPD, had a better clinical outcome when MTX was withdrawn than did other patients with MTX-LPD.