Monoclonal Antibody Stimulation Research Articles

12422 Linsitinib Inhibits Proliferation And Induces Apoptosis Of IGF-1R And TSH-R Expressing Cells

Abstract Disclosure: M. Luffy: None. A. Ganz: None. J. Ropertz: None. R. Douglas: Employee; Self; Sling Therapeutics. R. Zeidan: Employee; Self; Sling Therapeutics. J. Kent: Employee; Self; Sling Therapeutics. J. Wolf: None. G.J. Kahaly: Grant Recipient; Self; Sling Therapeutics. Background: The insulin-like growth factor 1 receptor (IGF-1R) and the thyrotropin receptor (TSH-R) are expressed on orbital target cells and thyrocytes. Targeting these pathways effectively improves thyroid eye disease (TED). Methods: The inhibitory effect of Linsitinib, a small molecule targeting the IGF-1R (Sling Therapeutics, Ann Arbor, MI, USA), on cell proliferation was investigated in an IGF-1R expressing cell line, NCI-H295R (ATCC, Manassas, VA, USA) and a Chinese Hamster Ovary (CHO) cell line overexpressing the TSH-R (QuidelOrtho, San Diego, CA, USA). An IGF-1R antagonist, Teprotumumab (BioVision, Milpitas, CA, USA) served as control. Both cell lines were plated in a 96-well format and treated with four concentrations of both compounds for 24 hours. After addition of tetrazolium, absorbance was measured (GloMax luminometer, Promega, Madison, WI, USA). Furthermore, the half-maximal inhibitory concentration (IC50) of TSH-R-Ab induced stimulation (stimulatory monoclonal antibody, mAb, M22, RSR, Cardiff, UK) of the TSH-R cell line was evaluated with a cell-based bioassay for blocking TSH-R-Ab (Thyretain TBI, QuidelOrtho). Cells were treated with ten rising concentrations of either Linsitinib, Linsitinib + Metformin, Teprotumumab, or a blocking TSH-R mAb (K1-70, RSR). The Kruskal-Wallis and/or the two-tailed Mann-Whitney tests were used for statistical comparisons. Results: Linsitinib strongly inhibited the proliferation of both cell lines at the following concentrations: 31,612.5 ng/mL (-78%, P=0.0031, IGF-1R cell line and -75%, P=0.0059, TSH-R cell line), as well as at 63,225 ng/mL (-73%, P=0.0073, IGF-1R cell line and -73%, P=0.0108, TSH-R cell line). Linsitinib induced morphologically confirmed apoptosis of both cell lines across all tested concentrations (Luna-FL cell counter, Logos Biosystems, Annandale, VA, USA). Compared to Teprotumumab, Linsitinib inhibited markedly more the proliferation of the IGF-1R cell line at all concentrations (Linsitinib versus Teprotumumab, P=0.0286). Teprotumumab inhibition ranged from -21 to -31% of the IGF-1R cell line across all concentrations, while it was significant only at 15,806.25 ng/mL with the TSH-R cell line (-15%, P=0.0396). In addition, in the TSH-R-Ab blocking bioassay, all tested compounds demonstrated strong inhibition across all ten dilutions (100%). The IC50 of Linsitinib was lower than Teprotumumab (147.1 ng/mL versus 160.6 ng/mL). Combining Metformin to Linsitinib did not further lower the IC50. Not surprisingly, the TSH-R blocking mAb K1-70 had the lowest IC50 of 20.57 ng/mL. Conclusions: Linsitinib effectively induces apoptosis and inhibits proliferation of both IGF-1R and TSH-R expressing target cells, also displaying a lower IC50 in the blocking TSH-R-Ab bioassay compared to Teprotumumab, hence demonstrating its therapeutic potential for TED. Presentation: 6/2/2024

Antitumor effects of NK cells expanded by activation pre‑processing of autologous feeder cells before irradiation in colorectal cancer.

Natural killer (NK) cells play a crucial role in early immune defenses against transformed cells and are used in the therapeutic management of cancer. However, it is difficult to sufficiently obtain high purity activated NK cells for clinical application. The function of NK cells is dependent on the balance of activating and inhibitory signals. Strong and diverse stimuli are required to increase the function of NK cells. Radiotherapy modulates the expression of various immunomodulatory molecules that recruit and activate NK cells. NK cell-mediated antibody-dependent cellular cytotoxicity is one of the most potent cytotoxic effects of NK cells against target cancer cells. To generate activated and irradiated autologous peripheral blood mononuclear cells (PBMCs), cytokine and monoclonal antibody stimulation followed by ionizing radiation was performed in the present study. The expanded NK cells were cultured for 21 days using activated/irradiated autologous PBMCs. Colorectal cancer cells (SW480 and HT-29) were used to analyze the expression of NK group 2D ligands and EGFR by radiation. The cytotoxicity of radiation plus NK cell-based targeted therapy against colorectal cancer cell lines was analyzed using flow cytometry. Activated and irradiated PBMCs exhibited significantly increased expression of various activating ligands that stimulated NK cells. In total, >10,000-fold high-purity activated NK cells were obtained, with negligible T-cell contamination. To confirm the antitumor activity of the NK cells expanded by this method, the expanded NK cells were treated with cetuximab, radiotherapy, or a combination of cetuximab and radiotherapy in the presence of human colorectal cancer cells. Expanded NK cells were effective at targeting human colorectal cancer cells, particularly when combined with cetuximab and radiotherapy. Thus, in the present study, a novel method for high-purity activated NK cell expansion was developed using activated and irradiated PBMCs. In addition, combined radiotherapy and antibody-based immunotherapy with expanded NK cells may be an effective strategy to enhance the efficiency of treatment against colorectal cancer.

High-fat diet blunts T-cell responsiveness in Nile tilapia

The reduced stress resistance and increased disease risk associated with high-fat diet (HFD) in animals have attracted increasing attention. However, the effects of HFD on adaptive immunity in early vertebrates, especially non-tetrapods, remain unknown. In this study, using Nile tilapia (Oreochromis niloticus) as a model, we investigated the effects of HFD on the primordial T-cell response in fish. Tilapia fed with an HFD for 8 weeks showed impaired lymphocyte homeostasis in the spleen, as indicated by the decreased number of both T and B lymphocytes and increased transcription of proinflammatory cytokines interferon-γ and interleukin-6. Moreover, lymphocytes isolated from HFD-fed fish or cultured in lipid-supplemented medium exhibited diminished T-cell activation in response to CD3ε monoclonal antibody stimulation. Moreover, HFD-fed tilapia infected by Aeromonas hydrophila showed decreased T-cell expansion, increased T-cell apoptosis, reduced granzyme B expression, and impaired infection elimination. Additionally, HFD attenuated adenosine 5’-monophosphate (AMP)-activated protein kinase (AMPK) activity in tilapia lymphocytes, which in turn upregulated fatty acid synthesis but downregulated fatty acid β-oxidation. Altogether, our results suggest that HFD impairs lymphocyte homeostasis and T cell-mediated adaptive immune response in tilapia, which may be associated with the abnormal lipid metabolism in lymphocytes. These findings thus provide a novel perspective for understanding the impact of HFD on the adaptive immune response of early vertebrates.

Adult Pulmonary Langerhans Cell Histiocytosis with Osseous Involvement: understanding this rare mimic of malignancy

Langerhans cells are dendritic cells that form the antigenic barrier of the human body. They occur in nearly any tissue but are most prevalent in the skin, submucosa of the bronchial tree, and other mucosae. Langerhans Cell Histiocytosis (LCH) develops when these cells damage the tissues in which they reside through a combination of inflammatory and monoclonal stimulation. The pulmonary variant of LCH involves the lung parenchyma and creates a wide variety of disturbances: pulmonary hypertension and both obstructive and restrictive lung disease. Osseous involvement, in addition to the pulmonary variant, presents with pulmonary masses and lytic bone lesions, which sparks suspicion for malignancy. Early recognition of this rare pathology is important as early treatment is clinically beneficial. The following explores a case of adult Pulmonary Langerhans Cell Histiocytosis with osseous involvement.

Expression of the myeloid-associated marker CD33 is not an exclusive factor for leukemic plasmacytoid dendritic cells

AbstractA new entity of acute leukemia coexpressing CD4+CD56+ markers without any other lineage-specific markers has been identified recently as arising from lymphoid-related plasmacytoid dendritic cells (pDCs). In our laboratory, cells from a patient with such CD4+CD56+ lineage-negative leukemia were unexpectedly found to also express the myeloid marker CD33. To confirm the diagnosis of pDC leukemia despite the CD33 expression, we demonstrated that the leukemic cells indeed exhibited pDC phenotypic and functional properties. In 7 of 8 other patients with CD4+CD56+ pDC malignancies, we were able to confirm that the tumor cells expressed CD33 although with variable expression levels. CD33 expression was shown by flow cytometry, reverse transcriptase-polymerase chain reaction, and immunoblot analysis. Furthermore, CD33 monoclonal antibody stimulation of purified CD4+CD56+ leukemic cells led to cytokine secretion, thus confirming the presence of a functional CD33 on these leukemic cells. Moreover, we found that circulating pDCs in healthy individuals also weakly express CD33. Overall, our results demonstrate that the expression of CD33 on CD4+CD56+ lineage-negative cells should not exclude the diagnosis of pDC leukemia and underline that pDC-specific markers should be used at diagnosis for CD4+CD56+ malignancies.

Protein tyrosine phosphatase 1B as a therapeutic target for Graves' orbitopathy in an in vitro model.

Graves’ orbitopathy (GO) is characterised in early stages by orbital fibroblast inflammation, which can be aggravated by oxidative stress and often leads to fibrosis. Protein tyrosine protein 1B (PTP1B) is a regulator of inflammation and a therapeutic target in diabetes. We investigated the role of PTP1B in the GO mechanism using orbital fibroblasts from GO and healthy non-GO subjects. After 24 hours of transfection with PTPN1 siRNA, the fibroblasts were exposed to interleukin (IL)-1β, cigarette smoke extract (CSE), H2O2, and transforming growth factor (TGF)-β stimulations. Inflammatory cytokines and fibrosis-related proteins were analysed using western blotting and/or enzyme-linked immunosorbent assay (ELISA). Reactive oxygen species (ROS) release was detected using an oxidant-sensitive fluorescent probe. IL-1β, tumor necrosis factor (TNF)-α, bovine thyroid stimulating hormone (bTSH), high-affinity human stimulatory monoclonal antibody of TSH receptor (M22), and insulin-like growth factor-1 (IGF-1) significantly increased PTP1B protein production in GO and non-GO fibroblasts. PTPN1 silencing significantly blocked IL-1β-induced inflammatory cytokine production, CSE- and H2O2-induced ROS synthesis, and TGF-β-induced expression of collagen Iα, α-smooth muscle actin (SMA), and fibronectin in GO fibroblasts. Silencing PTPN1 also decreased phosphorylation levels of Akt, p38, and c-Jun N-terminal kinase (JNK) and endoplasmic reticulum (ER)-stress response proteins in GO cells. PTP1B may be a potential therapeutic target of anti-inflammatory, anti-oxidant and anti-fibrotic treatment of GO.

Influence of hepatitis B virus X gene on apoptosis of hepatic cells mediated by Fas

Objective: To investigate the influence of hepatitis B virus X gene (HBx) on apoptosis of hepatic cells mediated by Fas in HePG2 cells. Methods: HBx eukaryotic vector pcDNA3.1(+)-X was transfected into HEPG2 cells with lipofectamine, and the null vector pcDNA3.1(+) and untransfected HEPG2 were used as normal controls. The cells were collected 72 h after transfection, and the expression of HBx mRNA and protein was determined using RT-PCR and Western blot, respectively. The mRNA expression of apoptosis-related genes Bcl-2 and Bax mRNA was also determined using RT-PCR. Cytotoxicity and apoptosis were evaluated using CCK-8 and flow cytometry, respectively, after HepG2-HBx and HepG2-3.1 cells were treated with stimulatory monoclonal antibody anti-Fas CH11. The t test was used for pairwise comparison. Results: The cell line HepG2-HBx was successfully established, as confirmed by RT-PCR and Western blot, and RT-PCR results showed that HepG2-HBx cells had significantly higher expression of Bcl-2 mRNA than HepG2-3.1 and HepG2 cells (P < 0.05), but had significantly lower expression of Bax mRNA than HepG2-3.1 and HepG2 cells (P < 0.05); CCK-8 and flow cytometry showed that anti-Fas CH11 had a lower cytotoxicity to HepG2-HBx cells and allowed for a lower apoptosis rate of HepG2-HBx cells compared with HepG2-3.1 and HepG2 cells. Conclusions: HBx can inhibit apoptosis of hepatic cells mediated by the Fas pathway.

Strategies for T Helper Cell Subset Differentiation from Naïve Precursors.

In vitro strategies to obtain different T helper cell subsets from naïve precursors are usually characterized by anti-CD3 plus anti-CD28 monoclonal antibody stimulation of naïve CD4+ T cells (derived from both peripheral blood or umbilical cord blood) in the presence of specific polarizing cytokines. In this chapter, we describe detailed protocols to obtain in vitro differentiation of human naïve CD4+ T cells into Th1, Th2, or Th17 cells.

A TNFR2-Agonist Facilitates High Purity Expansion of Human Low Purity Treg Cells.

Regulatory T cells (Treg) are important for immune homeostasis and are considered of great interest for immunotherapy. The paucity of Treg numbers requires the need for ex vivo expansion. Although therapeutic Treg flow-sorting is feasible, most centers aiming at Treg-based therapy focus on magnetic bead isolation of CD4+CD25+ Treg using a good manufacturing practice compliant closed system that achieves lower levels of cell purity. Polyclonal Treg expansion protocols commonly use anti-CD3 plus anti-CD28 monoclonal antibody (mAb) stimulation in the presence of rhIL-2, with or without rapamycin. However, the resultant Treg population is often heterogeneous and pro-inflammatory cytokines like IFNγ and IL-17A can be produced. Hence, it is crucial to search for expansion protocols that not only maximize ex vivo Treg proliferative rates, but also maintain Treg stability and preserve their suppressive function. Here, we show that ex vivo expansion of low purity magnetic bead isolated Treg in the presence of a TNFR2 agonist mAb (TNFR2-agonist) together with rapamycin, results in a homogenous stable suppressive Treg population that expresses FOXP3 and Helios, shows low expression of CD127 and hypo-methylation of the FOXP3 gene. These cells reveal a low IL-17A and IFNγ producing potential and hardly express the chemokine receptors CCR6, CCR7 and CXCR3. Restimulation of cells in a pro-inflammatory environment did not break the stability of this Treg population. In a preclinical humanized mouse model, the TNFR2-agonist plus rapamycin expanded Treg suppressed inflammation in vivo. Importantly, this Treg expansion protocol enables the use of less pure, but more easily obtainable cell fractions, as similar outcomes were observed using either FACS-sorted or MACS-isolated Treg. Therefore, this protocol is of great interest for the ex vivo expansion of Treg for clinical immunotherapy.

Anticancer Teamwork: Cross-Presenting Dendritic Cells Collaborate with Therapeutic Monoclonal Antibodies.

Cross-presentation of tumor antigens represents a key pathway in antitumor immune responses that can be exploited to synergize not only with the already prominent "checkpoint blockade," but also with newer attempts to use T-cell stimulatory monoclonal antibodies in immunotherapy.

Abstract A04: Systemic agonistic anti-CD40 treatment of tumor bearing mice modulates hepatic myeloid suppressive cells and causes immune-mediated liver damage

Abstract Immune stimulatory monoclonal antibodies are currently evaluated as antitumor agents in clinical trials. Although overall toxicity appears to be moderate, liver toxicities have been reported and are not completely understood. Therefore, we decided to study the effect of systemic CD40 antibody treatment on the liver immune microenvironment. Agonistic CD40 antibody or isotype control was injected intraperitoneally into naïve and tumor-bearing mice. Liver enzymes, histologies and immune infiltrates were analyzed after antibody administration. The effect of agonistic CD40 administration was evaluated using bone marrow chimeras and genetically modified mouse strains Cd40-/- and Nox2-/-. Mouse and human tumor-induced myeloid suppressive cells were cultured to address changes in their immune function upon CD40 ligation. Agonistic CD40 antibody caused liver damage within 24 hours after injection in two unrelated tumor models and mice strains. Using bone marrow chimeras we could demonstrate that CD40 antibody-induced hepatitis in tumor-bearing mice was dependent on the presence of CD40+ immune cells. Agonistic CD40 ligation-dependent liver damage was induced by the generation of reactive oxygen species. Furthermore, agonistic CD40 antibody resulted in increased CD80 and CD40 positive liver CD11b+Gr-1+ immature myeloid cells. CD40 ligation on tumor-induced hepatic myeloid cells or CD14+HLA-DRlow PBMC from cancer patients reduced their immune suppressor function. Collectively, agonistic CD40 antibody activates the tumor-induced liver myeloid suppressive compartment, enhancing acute inflammation and thus liver damage. Our data in murine and human myeloid suppressive cells point towards a pivotal role for CD40 as a key molecule in modulating myeloid suppressive cell plasticity. Citation Format: Jose Medina-Echeverz, Chi Ma, Tobias Eggert, Tim F. Greten. Systemic agonistic anti-CD40 treatment of tumor bearing mice modulates hepatic myeloid suppressive cells and causes immune-mediated liver damage. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr A04.

Aflatoxin B1 Suppressed T-Cell Response to Anti-pig-CD3 Monoclonal Antibody Stimulation in Primary Porcine Splenocytes: A Role for the Extracellular Regulated Protein Kinase (ERK1/2) MAPK Signaling Pathway.

The aim of the present study is to investigate whether aflatoxin B1 (AFB1)-induced immunotoxicity is associated with oxidative stress and the expression of extracellular regulated protein kinases (ERK) 1/2. The primary splenocytes isolated from healthy pigs were activated and proliferated by anti-pig-CD3 monoclonal antibodies (mAb) in the present experiment, which is an antigen-specific stimulant. Results indicated that cell proliferation and interleukin-2 (IL-2) production were significantly suppressed by AFB1 from 4 to 8 μg/mL in a dose-dependent manner compared to the control group. Furthermore, AFB1 significantly increased malondialdehyde (MDA) levels, decreased reduced glutathione (GSH) and total superoxide dismutase levels, and up-regulated p-ERK1/2 expression in the activated splenocytes. N-Acetyl-l-cysteine blocked anti-CD3-induced T-cell suppression by AFB1 through increasing intracellular concentrations of GSH levels, decreasing MDA levels, and down-regulated p-ERK1/2 expression, respectively. Inhibition of the ERK1/2 expression by ERK-specific iRNA attenuated the decrease of T-cell proliferation and IL-2 production induced by AFB1. It was concluded that AFB1 inhibits anti-CD3-induced lymphocyte proliferation and IL-2 production by the oxidative stress mediated ERK1/2 MAPK signaling pathway.

Biological drugs in ANCA-associated vasculitis

The anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitides granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangiitis (EGPA) and microscopic polyangiitis (MPA) constitute a wide spectrum of clinical manifestations of systemic vasculitis which may range from limited disease to organ or life-threatening disease. The introduction of biologics for the management of severe ANCA-associated vasculitis and severe, relapsing disease refractory to conventional immunosuppressants, has significantly improved the clinical prognosis of these autoimmune disorders. Rituximab, an anti-CD20 monoclonal antibody is licenced for remission induction in severe GPA and MPA and the management of severe relapsing, refractory GPA and MPA. Belimumab, an anti-B lymphocyte stimulatory monoclonal antibody is in clinical trials for the management of the ANCA-associated vasculitis GPA. Mepolizumab and Omalizumab are biologics which have been reported to be efficacious in refractory asthma associated with EGPA. The role of anti-TNF therapy and T cell targeting drugs in ANCA-associated vasculitis is less clear due to limited study data. This review will summarise the clinical trials and clinical practice use of biologic treatment strategies for the management of ANCA-associated vasculitis.

Aminopenicillin-associated exanthem: lymphocyte transformation testing revisited.

The lymphocyte transformation test (LTT) has been promoted as in-vitro test for diagnosis of drug hypersensitivity. For determination of statistical LTT sensitivity, series of patients with clinically uniform reactions followed by complete drug hypersensitivity work-up are mandatory. Assessment of LTT specificity requires control patients who tolerated exposure to the drug studied. To prospectively determine the diagnostic value of the LTT in a clinically and diagnostically well-defined series of patients. Patients with exanthematous skin eruptions after ampicillin (AMP) intake were included in this study. After exclusion or confirmation of delayed-onset allergic AMP hypersensitivity by skin and provocation testing, two independent LTTs were performed: one standard LTT and a modified LTT with additional anti-CD3/anti-CD28 monoclonal antibody stimulation. By testing, delayed-onset allergic AMP hypersensitivity was diagnosed in 11 patients and definitely ruled out in 26. The standard LTT reached a diagnostic sensitivity of 54.5% while the modified LTT yielded 72.7%. However, the methodical test modification resulted in a decline of specificity from 92.3% (standard LTT) to 76.9%. In cases of AMP-associated exanthems, the diagnostic value of the LTT compared with routine allergy testing is limited. When evaluating such exanthems, provocation testing remains the gold standard. Delayed reading of intradermal skin tests remains most useful to avoid positive provocation reactions.

Agonistic CD40 antibody induces immune-mediated liver damage and modulates tumor-induced myeloid suppressive cells

Meeting abstracts Immune stimulatory monoclonal antibodies are currently evaluated as anti/cancer agents in clinical trials. While overall toxicity seems to be moderate, liver toxicities have been reported and are not completely understood. Based on the observation that CD11b+Gr-1+ MDSC accumulate

Sex, gender and immunosenescence: a key to understand the different lifespan between men and women?

Sex, gender and immunosenescence: a key to understand the different lifespan between men and women?

Slower immune system aging in women versus men in the Japanese population

BackgroundGender-related differences in humans are commonly observed in behaviour, physical activity, disease, and lifespan. However, the notion that age-related changes in the immune system differ between men and women remains controversial. To elucidate the relationship between immunological changes and lifespan, peripheral blood mononuclear cells from healthy Japanese subjects (age range: 20–90 years; N = 356) were analysed by using three-colour flow cytometry. The proliferative activities and cytokine-producing capacities of T cells in response to anti-CD3 monoclonal antibody stimulation were also assessed.ResultsAn age-related decline in the number of T cells, certain subpopulations of T cells (including CD8+ T cells, CD4+CDRA+ T cells, and CD8+CD28+ T cells), and B cells, and in the proliferative capacity of T cells was noted. The rate of decline in these immunological parameters, except for the number of CD8+ T cells, was greater in men than in women (p < 0.05). We observed an age-related increase or increasing trend in the number of CD4+ T cells, CD4+CDRO+ T cells, and natural killer (CD56+CD16+) cells, as well as in the CD4+ T cell/CD8+ T cell ratio. The rate of increase of these immunological parameters was greater in women than in men (p < 0.05). T cell proliferation index (TCPI) was calculated from the T cell proliferative activity and the number of T cells; it showed an age-related decline that was greater in men than in women (p < 0.05). T cell immune score, which was calculated using 5 T cell parameters, also showed an age-related decline that was greater in men than in women (p < 0.05). Moreover, a trend of age-related decreases was observed in IFNγ, IL-2, IL-6, and IL-10 production, when lymphocytes were cultured with anti-CD3 monoclonal antibody stimulation. The rate of decline in IL-6 and IL-10 production was greater in men than in women (p < 0.05).ConclusionAge-related changes in various immunological parameters differ between men and women. Our findings indicate that the slower rate of decline in these immunological parameters in women than that in men is consistent with the fact that women live longer than do men.

Immunosuppressive Effects of DTCM-G, a Novel Inhibitor of the mTOR Downstream Signaling Pathway

A newly developed compound, 3-[(dodecylthiocarbonyl)methyl]-glutarimide (DTCM-G), has been shown to inhibit nuclear translocation of c-Fos/c-Jun in a murine macrophage cell line. Herein, we studied the immunosuppressive properties and potency of DTCM-G. Using purified mouse T cells, the in vitro effects of DTCM-G on activation, cytokine production, proliferation, and cell cycle progression were assessed, and a possible molecular target of DTCM-G was investigated. In a BALB/c (H-2(d)) to C57BL/6 (H-2(d)) mouse heart transplantation model, transplant recipients were administered DTCM-G, a calcineurin inhibitor (tacrolimus), and a nuclear factor-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ). Treatment drugs were administered daily for 14 days after transplantation. Alloimmune responses were assessed in addition to graft survival time. After anti-CD3+anti-CD28 monoclonal antibody stimulation, DTCM-G significantly suppressed proliferation, interferon-γ production, and cell cycle progression of activated T cells but not CD25 expression or interleukin-2 production. These effects were accompanied by inhibition of 70-kDa S6 protein kinase phosphorylation, a downstream kinase of the mammalian target of rapamycin. The addition of tacrolimus and DHMEQ to DTCM-G resulted in a robust inhibition of T-cell proliferation. In vivo combination therapy of DTCM-G plus either tacrolimus or DHMEQ significantly suppressed alloreactive interferon-γ-producing precursors and markedly prolonged cardiac allograft survival. Furthermore, combination of all three agents markedly inhibited alloimmune responses and permitted long-term cardiac allograft survival. DTCM-G inhibits T cells by suppressing the downstream signal of mammalian target of rapamycin. DTCM-G in combination with tacrolimus and DHMEQ induces a strong immunosuppressive effect in vivo.

A Novel Function of CD26-Mediated Costimulation in the Cytotoxic Activity of Human CD8+ T Cells in Xenogeneic Chronic Graft-Versus-Host Disease (cGVHD) and GVL Mice Model.

Abstract 3548Poster Board III-485CD26 is a 110-kDa cell surface glycoprotein with known dipeptidyl peptidase IV (DPPIV) activity in its extracellular domain, capable of cleaving amino-terminal dipeptides with either L-proline or L-alanine at the penultimate position. CD26 activity is dependent on cell type and the microenvironment, which influence its multiple biological roles. CD26 plays an important role in immunology, autoimmunity, diabetes and cancer. The role of CD26 in immune regulation has been extensively characterized, with our recent findings elucidating its linkage with signaling pathways and structures involved in T cells activation as well as antigen presenting cell (APC)-T-cell interaction. CD26 is preferentially expressed on human CD4+ memory T cells and CD4+CD45RO+CD26+ T cells exhibit response maximally to the recall antigen tetanus toxoid. Human T-helper 1 (Th1) cells display a higher expression of CD26 and are much more sensitive to CD26-mediated costimulation than human Th2 cells. In contrast, the role of CD26 in human CD8+ T cells still remains to be elucidated, while CD8+ T cells express CD26 as well as CD4+ T cells. In this study, we studied the effector function of CD26-mediated costimulation of CD8+ T cells. In comparison with CD28-medaited costimulation, which is one of representative T cell costimulatory pathway, CD26-mediated costimulation in CD8+ T cells showed delayed proliferation than that of CD28 stimuatlion, but finally expanded to a similar extent. The secretion of inflammatory cytokines, TNF-alpha and IFN-gamma, was strongly induced after CD26-mediated costimulation. In contrast, the secretion of IL-2 and IL-5 was significantly less as compared with CD28-mediated costimulation. Finally, we showed that the expression of Granzyme B, one of the major effector molecules in the cytotoxic activity of CD8+ T cells, was markedly enhanced by CD26-mediated costimulation in dose dependent manner of anti-CD26 monoclonal antibody stimulation. Moreover, with CD26-mediated costimulation, CD8+ T cells were observed to kill target cells in a Granzyme B-dependent manner. Next, we examined CD26-dependent organ injury by human T cells using xenogeneic chronic GVHD (x-cGVHD) mice model. About 6 weeks after transplantation of human peripheral blood mononuclear cells (PBMC) into NOG-Scid mice, mice develop loss pf hair, loss of weight, and human CD8+ lymphocytes infiltration into liver, lung, and salivary glands, which exhibit pathological changes of cGVHD. Administration of anti-human CD26 mAb decreased onset of x-cGVHD, while human lymphocytes were grafted successfully. Finally, we examined whether GVL effect is exerted via CD26-mediated costimulation, using x-cGVHD mice model in which P388 leukemic cells were grafted subcutaneously. In this tumor-graft model, P388 cells were not grafted in mice with onset of x-cGVHD, which indicated that GVL effect was exerted by human lymphocytes. On the other hand, P388 cells were also diminished in mice with decreased x-cGVHD by administration of anti-CD26 mAb. Taken together, our data strongly suggest that CD26-mediated costimulation in CD8+ T cells deeply involves in the pathology of cGVHD. The present study offers a novel notion that CD26 may become one of therapeutic targets of GVHD without impairment of GVL effect. Disclosures:Yamada:Y's Therapeutics: Membership on an entity's Board of Directors or advisory committees. Dang:Y's Therapeutics: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Morimoto:Y's Therapeutics: Patents & Royalties, a board member.

Impact of culture medium on the expansion of T cells for immunotherapy

Encouraging evidence of clinical benefits from cancer immunotherapy is beginning to accumulate in several clinical trials. Cancer immunotherapy is based on two main methods, active vaccination and cell-transfer therapy. The ex vivo expansion of T cells is required to monitor vaccine-induced antigen-specific T cells or prepare large numbers of reactive lymphocytes for adoptive transfer. We examined the influence of culture medium on T-cell growth, cytotoxicity and phenotype after activation using immobilized anti-CD3 monoclonal antibody or Zoledronate stimulation. Peripheral blood mononuclear cells (PBMC) were cultured in RPMI, AIM-V or OpTmizer with or without autologous serum. When supplemented with sufficient serum, RPMI was a good culture medium for T-cell expansion following anti-CD3 stimulation. Addition of autologous serum to AIM-V or OpTmizer increased the numbers of cells obtained to a similar extent, but their phenotype and function were quite different. Activated T cells cultured with OpTmizer mediated greater cytotoxicity than any other culture. Regardless of the media used, the main population expanded after CD3 stimulation was CD3(+) CD8(+). While more CD3(+) CD4(+) T cells were induced in RPMI and AIM-V, more CD3(-) CD56(+) cells and CD3(+) CD56(+) T cells were induced in OpTmizer. When cells were stimulated by Zoledronate for 14 days, approximately 7.2 times and 11.5 times more gammadelta T cells were obtained in OpTmizer than AIM-V or RPMI, respectively. Successful immunotherapy depends on the selection of appropriate culture media to support efficient expansion of the type of T cell desired.