Anti-CD3/anti-CD28 bead stimulation overcomes CD3 unresponsiveness in patients with head and neck squamous cell carcinoma

Vitamin D deficiency in head and neck cancer patients - prevalence, prognostic value and impact on immune function

Vitamin D deficiency is frequently observed in human cancer patients and a prognostic relevance could be shown for some entities. Additionally, it is known that vitamin D can stimulate the patients' antitumor immunity. However, valid epidemiological data for head and neck squamous cell carcinoma (HNSCC) patients are sparse and functional studies on a possible connection between vitamin D and the patients' immune system are missing. 25-OH vitamin D serum levels were analyzed in 231 HNSCC patients and 232 healthy controls and correlated with clinical data and patient survival. Intra- and peritumoral infiltration with T-cell, NK-cell and macrophage populations was analyzed in 102 HNSCC patients by immunohistochemistry. In 11 HNSCC patients, NK-cells were isolated before and after vitamin D substitution and analyzed for their cytotoxic activity directed against a HNSCC cell line. Vitamin D serum levels were significantly lower in HNSCC patients compared with healthy controls. Low vitamin D levels were associated with lymphatic metastasis and a negative HPV status and were a significant predictor of poor overall survival. HNSCC patients with severe vitamin D deficiency showed significantly altered intra- and peritumoral immune cell infiltrate levels. After vitamin D substitution, the patients' NK cells showed a significant rise in cytotoxic activity. Taken together, we could show that Vitamin D deficiency is highly prevalent in HNSCC patients and is a predictor of poor survival. Vitamin D substitution used as an adjuvant in immune therapies such as cetuximab and nivolumab treatment could support antitumorigenic immune responses, thus contributing to the improvement of the patients' prognosis in the context of a multimodal therapy.

Alterations in adaptive immunity persist during long-duration spaceflight

Background:

It is currently unknown whether immune system alterations persist during long-duration spaceflight. In this study various adaptive immune parameters were assessed in astronauts at three intervals during 6-month spaceflight on board the International Space Station (ISS).

AIMS:

To assess phenotypic and functional immune system alterations in astronauts participating in 6-month orbital spaceflight.

Methods:

Blood was collected before, during, and after flight from 23 astronauts participating in 6-month ISS expeditions. In-flight samples were returned to Earth within 48 h of collection for immediate analysis. Assays included peripheral leukocyte distribution, T-cell function, virus-specific immunity, and mitogen-stimulated cytokine production profiles.

Results:

Redistribution of leukocyte subsets occurred during flight, including an elevated white blood cell (WBC) count and alterations in CD8⁺ T-cell maturation. A reduction in general T-cell function (both CD4⁺ and CD8⁺) persisted for the duration of the 6-month spaceflights, with differential responses between mitogens suggesting an activation threshold shift. The percentage of CD4⁺ T cells capable of producing IL-2 was depressed after landing. Significant reductions in mitogen-stimulated production of IFNγ, IL-10, IL-5, TNFα, and IL-6 persisted during spaceflight. Following lipopolysaccharide (LPS) stimulation, production of IL-10 was reduced, whereas IL-8 production was increased during flight.

Conclusions:

The data indicated that immune alterations persist during long-duration spaceflight. This phenomenon, in the absence of appropriate countermeasures, has the potential to increase specific clinical risks for crewmembers during exploration-class deep space missions.

In vitro evaluation of the effects of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) on IL-2 production in human T-cells

Perfluorinated compounds, such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), have been shown to alter various immune functions suggesting they are immunotoxic. This study assessed the effects of PFOS and PFOA on interleukin (IL)-2 production in the human Jurkat T-cell line and PFOS in healthy human primary T cells. Jurkat cells were stimulated with phytohemagglutinin (PHA)/phorbol myristate acetate (PMA), anti CD-3/anti CD-28, or anti CD-3, and dosed with 0, 0.05, 0.1, 0.5, 1, 5, 10, 50, 75, or 100 µg ml(-1) PFOS or 0, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 5, or 10 µg ml(-1) PFOA. Jurkat cells stimulated with PHA/PMA or anti CD-3 exhibited decreased IL-2 production beginning at 50 µg PFOS ml(-1) and 5 µg PFOS ml(-1) respectively, but stimulation with anti-CD3/anti-CD28 resulted in no changes compared with the control. Addition of the PPAR-alpha antagonist GW6471 to PFOS-dosed cells stimulated with PHA/PMA resulted in decreases in IL-2 production starting at 50 µg PFOS ml(-1), which suggests PFOS affected T-cell IL-2 production via PPAR-alpha-independent mechanisms. Exposure to PFOA, PFOA + GW6471, or PFOS + PFOA in Jurkat cells resulted in no significant differences in IL-2 production. In vitro dosing studies using healthy primary human CD4+ T cells were consistent with the Jurkat results. These data demonstrated that PFOA did not impact IL-2 production, but PFOS suppressed IL-2 production in both a human cell line and human primary cells at dose levels within the high end of the human exposure range. A decrease in IL-2 production is characteristic of autoimmune diseases such as systemic lupus erythematosus and should be further investigated.

Immune regulatory activity of vitamin d3 in head and neck cancer

While vitamin D exhibits a multitude of cellular effects that can impact on cancer development and progression, this review focuses on its immune modulatory effects. These immune modulatory effects can be both direct and indirect. Compared to other cancer types, head and neck squamous cell carcinomas (HNSCC) have received less attention, but are a fascination immunologically because of the profound extent to which they inhibit immune defenses. This review describes the mechanisms of some of these immune inhibitory processes and how vitamin D can help overcome aspects of this immune suppression.

Regulation of Th1/Th17 cytokines and IDO gene expression by inhibition of calpain in PBMCs from MS patients

Multiple sclerosis (MS) pathology is marked by the massive infiltration of myelin-specific T cells into the central nervous system (CNS). During active disease, pro-inflammatory Th1/Th17 cells predominate over immunoregulatory Th2/Treg cells. Here, we show that calpain inhibition downregulates Th1/Th17 inflammatory cytokines and mRNA in MS patient peripheral blood mononuclear cells (PBMCs) activated with anti-CD3/28 or MBP. Interestingly, calpain inhibition elevated IDO gene expression in MS PBMCs, which was markedly decreased in calpain expressing cells. Functional assay showed that incubation of MS patient PBMCs with calpain inhibitor or recombinant IDO attenuates T cell proliferation. These results suggest that calpain inhibition may attenuate MS pathology and augment the efficacy of standard immunomodulatory agents used to treat this disease.

Covalent linking of proteins and cytokines to suture: Enhancing the immune response of head and neck cancer patients

BACKGROUND

The immune system of advanced stage head and neck cancer patients is frequently suppressed. Poor immune function has been correlated with poor clinical outcome. Immunotherapeutic strategies have been previously attempted in an effort to enhance immune function and improve survival. Previous studies have shown surgical suture can be transformed into an immune stimulant capable of activating the T lymphocytes of cancer patients. The development of a process for covalently linking proteins and cytokines to suture could have enormous potential for the in vivo manipulation of the immune system.

HYPOTHESIS

We hypothesize proteins and cytokines can be covalently linked to surgical suture while preserving their functional properties.

STUDY DESIGN

Prospective study testing normal donor and head and neck squamous cell carcinoma (HNSCC) patient lymphocytes.

METHOD

Polyester suture was acid hydrolyzed followed by reacting with 1-ethyl-3(-3-dimethylamino propyl carbodiimide) (EDAC) to create a suture-EDAC intermediate. Next, selected proteins (horseradish peroxidase [HRP] or bovine serum albumin [BSA]) or cytokines (interleukin [IL]-2 or interferon [IFN]-gamma) were reacted with the suture-EDAC intermediate to test the covalent linkage of the selected protein or cytokine to suture. Functional activity of the linked proteins was measured spectrophotometrically. The linking of cytokines to suture was tested by stimulating normal donor peripheral blood lymphocytes (PBL) or HNSCC patients' lymphocytes. The functional activity was confirmed by proliferation, enzyme linked immunoadsorbent assay (ELISA), and phenotype expression of T cells. RESULTS The conditions for optimally linking a protein to polyester suture were defined using HRP as a model protein. HRP retained its enzymatic activity. The optimal conditions for linking IL-2 or IFN-gamma were defined. The covalently linked cytokines retained their immune enhancing properties for stimulating PBL and lymph node lymphocytes (LNL) from HNSCC patients to proliferate, generate a TH1 immunologic profile of cytokines (IL-2, IL-12, IFN-gamma), and stimulate T lymphocytes.

CONCLUSION

This is the first report to demonstrate that cytokines can be covalently linked to surgical sutures and retain their immune-stimulating properties. Proteins linked to suture also retained their enzymatic activity. The clinical implications of functionally active cytokines or proteins linked to surgical suture may be very significant in the future for manipulating the immune system in vivo or enhancing wound healing.

Secretion of vascular endothelial growth factor by oral squamous cell carcinoma cells skews endothelial cells to suppress T-cell functions

Patients with oral squamous cell carcinoma (OSCC) have severe defects in antitumor immune function. Endothelial cells are potential regulators of immune cell function and have therefore been examined to determine their role in tumor-induced immune suppression. The present studies demonstrated that supernatants from endothelial cells exposed to OSCC-conditioned media (endo(OSCC-sup)) exhibited elevated levels of the immune suppressive products prostaglandin E(2) (PGE(2)) and vascular endothelial growth factor (VEGF) compared with supernatants from endothelial cells treated with medium alone (endo(medium)) or with keratinocyte-conditioned medium (endo(ker-sup)). Antibody neutralization of OSCC-derived VEGF prevented tumor-conditioned media from inducing endothelial cells to increase production of PGE(2)and VEGF. Furthermore, treatment of T-cells with supernatants from endo(OSCC-sup) resulted in diminished T-cell proliferation and decreased interferon-gamma (IFN-gamma) production compared with T-cells treated with medium or supernatants from endo(medium) or endo(ker-sup) controls. T-cell levels of granzyme B and perforin were reduced after treatment with supernatant from endo(OSCC-sup) compared with control treatments. The addition of VEGF neutralizing antibody to the OSCC-conditioned medium prevented endothelial cells from being skewed to downregulate T-cell proliferation and production of IFN-gamma, perforin, and granzyme B. Taken together, these studies provide support for the use of VEGF-targeting therapies as an immunotherapeutic agent to block induction of immune suppressive endothelial cells in patients with OSCC.

Oral premalignant lesions induce immune reactivity to both premalignant oral lesions and head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy, and despite advances in treatments, the 5-year survival has remained at less than 50%. One treatment strategy is to focus on patients with premalignant oral lesions that carry a high-risk for developing recurrent premalignant lesions and HNSCC disease. As an initial attempt to determine if immune therapy has the potential to be protective in these patients, studies determined if premalignant lesions express tumor antigens that have previously been shown to be expressed on HNSCC. Immunohistochemical analyses showed prominent expression of epidermal growth factor receptor in premalignant lesions, even in lesions with mild dysplasia. MUC-1 and carcinoembryonic antigen were expressed in most patient samples, while NY-ESO-1 was less frequently expressed. Each of these antigens was expressed on HNSCC. This provided the rationale for determining if premalignant oral lesions could be used to stimulate autologous peripheral blood mononuclear leukocytes (PBML) to react against heterologous premalignant lesions and HNSCC. Following sensitization with autologous premalignant lesions, PBML responded to a challenge with either heterologous premalignant oral lesion cells or HNSCC by releasing IFN-gamma. In addition, sensitization with autologous premalignant lesion lysates generated cytolytic activity by both PBML and T cells against allogeneic premalignant lesion cells and HNSCC. These studies show the feasibility of using premalignant oral lesions to stimulate immune reactivity against both premalignant oral lesions as well as HNSCC.

Cytokine-containing gelfoam implants at a postsurgical tumor excision site to stimulate local immune reactivity

We previously demonstrated increased numbers of CD34(+) progenitor cells in the peripheral blood of tumor bearers. Also demonstrated was the feasibility of chemoattracting these cells by sponge implants containing VEGF. The present study used a murine Lewis lung carcinoma (LLC) model to test if CD34(+) cells that are chemoattracted to a tumor excision site can be differentiated in situ into dendritic cells and whether this leads to increased local immune reactivity. After surgically excising established LLC tumors, mice received at the excision site gelatin sponge implants containing VEGF to chemoattract CD34(+) cells, and/or GM-CSF plus SCF to induce CD34(+) cell differentiation into dendritic cells. In some studies, lysates of GFP-transfected LLC cells (LLC(GFP)) were also included in the implants as a source of tumor antigen. After 2 weeks, implants and local lymph nodes were removed and analyzed. Implants containing VEGF, GM-CSF/SCF or VEGF/GM-CSF/SCF had a higher proportion of CD34(+) cells compared to control implants. However, the number of dendritic cells was higher in implants containing GM-CSF/SCF or VEGF/GM-CSF/SCF than those containing either VEGF or diluent. Regional lymph node from mice containing GM-CSF/SCF or VEGF/GM-CSF/SCF implants showed increased dendritic cell levels. However, when lysates from LLC(GFP) were added to the implants, the highest proportion of dendritic cells associated with GFP was in lymph nodes of mice containing GM-CSF/SCF implants. Lymph node cells from mice with GM-CSF/SCF or VEGF/GM-CSF/SCF had a higher level of proliferation and IFN-gamma secretion in response to in vitro LLC lysate challenge, with the greatest response being from lymph node cells of mice with GM-CSF/SCF implants. These results suggest the feasibility of using GM-CSF/SCF-containing implants to increase dendritic cell levels, uptake of tumor antigens, trafficking to lymph nodes and stimulation of immune reactivity at tumor excision sites with residual tumor.

Combination docetaxel plus vitamin D(3) as an immune therapy in animals bearing squamous cell carcinomas

OBJECTIVE

Background tumor growth results in the mobilization of immune inhibitory CD34(+) progenitor cells. However, vitamin D(3) can differentiate the CD34(+) cells into immune stimulatory dendritic cells. This study determined if docetaxel treatment could increase the impact of the vitamin D(3) to generate dendritic cells.

METHODS

The murine squamous cell carcinoma model, SCC VII/SF, which is often used as a head and neck cancer model, was used to determine the immunological effects of two cycles of docetaxel plus vitamin D(3).

RESULTS

Vitamin D(3) with or without docetaxel was similarly effective in reducing CD34(+) cell levels within the spleen, lymph nodes, and tumor. Dendritic cell levels were similarly enhanced in the lymph nodes by vitamin D(3) alone or combined with docetaxel. However, the combination treatment caused a prominent increase in intratumoral levels of active T cells, which was not observed by the individual treatments.

CONCLUSION

Incorporating docetaxel treatment with vitamin D(3) differentiation-inducing treatment enhances intratumoral immune responsiveness.

Morphological changes of regional lymph node in squamous cell carcinoma of the oral cavity

BACKGROUND

Regional immune responses with various types of cancer have been studied histopathologically, however, the prognostic value remains conflicting. The aim of this study was to evaluate morphological changes related to lymph node metastasis and the prognostic value for oral cavity squamous cell carcinoma.

METHODS

With histopathologic whole architecture of 430 lymph nodes, gross area, germinal center (GC) area, paracortical area (PA), and tumor area were measured.

RESULTS

Metastatic node had significantly lower distribution ratio of PA to lymphoarea than that of tumor-free node. GC area was not constantly associated with lymph node metastasis. In Cox multivariate analysis, the mean ratio of PA to gross area/lymphoarea was an independent prognostic factor.

CONCLUSIONS

The proportion of PA to gross/lymph area was associated with lymph node metastasis and long-term survival and may be useful in stratification of those patients for a requirement of adjuvant treatments.

Bioactive Suture

PURPOSE

We have proposed to characterize the mechanism through which bioactive surgical sutures generate a T(H)1 immune response and to define the immune-stimulating half-life of the sutures.

EXPERIMENTAL DESIGN

Bioactive sutures of interferon gamma (IFNgamma), interleukin 2 (IL-2), anti-CD3/CD28, anti-CD3/CD28 + IL-2, or anti-CD3/CD28 + IFNgamma sutures were used to stimulate lymphocytes from normal donors and from head and neck cancer patients in vitro over a 24-day period. Cell supernatants were analyzed by ELISA, and T cells were phenotyped to characterize the immune response generated. Intracellular cytokine staining was performed to measure the expansion of flu-specific T cells. Electromobility shift assay and supershift assay were used to measure the intranuclear DNA binding activity of nuclear factor kappaB and its p65 subunit in T cells activated by sutures in the presence and absence of a proteasome inhibitor, MG-132.

RESULTS

Anti-CD3/CD28, anti-CD3/CD28 + IL-2, or anti-CD3/CD28 + IFNgamma generated a prolonged T(H)1 immune response for 18 days in vitro. Anti-CD3/CD28 expanded flu-specific T cells. Activated T cells demonstrated enhanced CD40 ligand (CD40L) expression within 72 hours of stimulation, which stimulated other cells to secrete IL-12. Stimulated T cells demonstrated increased intranuclear expression of nuclear factor-kappaB, which was blocked by MG-132, and also reduced CD40L and IL-12 expression.

CONCLUSIONS

This is the first report to demonstrate that bioactive surgical sutures can generate a prolonged T(H)1 immune response and expand flu-specific T cells. Bioactive sutures, which are primarily a T-cell stimulant, also stimulated other cells to secrete IL-12 and prolonged the immune response. Sutures may provide a novel in situ stimulating strategy for enhancing the immune system of cancer patients.

Incomplete Th2 skewing of cytokines in plasma of patients with squamous cell carcinoma of the head and neck

Levels of cytokines, and in particular those that reflect Th1 or Th2 bias, were measured in the plasma of patients with head and neck squamous cell carcinomas (HNSCC). Compared with plasma cytokine levels of age-matched controls, cytokine levels in HNSCC patients suggested a shift to a Th2 bias as levels of the Th2 cytokines interleukin-4 (IL-4), IL-6, and IL-10 were increased, and levels of the Th1 cytokine interferon-gamma (IFN-gamma) were decreased. However, levels of the Th1 cytokines IL-2 and granulocyte macrophage-colony-stimulating factor (GM-CSF) were increased, which is not consistent with full Th2 skewing. Assessment of cytokine levels in patients with malignancies other than HNSCC demonstrated many similarities to HNSCC patients, but HNSCC patients exhibited a more pronounced increase in GM-CSF levels and a decline in IFN-gamma levels. For most cytokines there was no association between the shifts in cytokine levels in HNSCC patients and either the extent of tumor burden or extent of metastasis. However, patients with large HNSCC tended to be the population that demonstrated increased levels of IL-4 and IL-6. These results suggest skewing toward a Th2 bias in HNSCC patients, with the Th2 shift being incomplete and indicative of the presence, rather than the extent, of malignant disease.

CD3/CD28-costimulated T1 and T2 subsets: differential in vivo allosensitization generates distinct GVT and GVHD effects

Adoptive T-cell therapy using CD3/CD28 co-stimulation likely requires in vivo generation of antigen specificity. Because CD28 promotes TH1/TC1 (T1) or TH2/TC2 (T2) differentiation, costimulation may generate donor T1 or T2 cells capable of differentially mediating allogeneic graft-versus-tumor (GVT) effects and graft-versus-host disease (GVHD). Costimulation under T1 or T2 conditions indeed generated murine TH1/TC1 cells secreting interleukin-2/interferon-gamma (IL-2/IFN-gamma) or TH2/TC2 cells secreting IL-4/IL-5/IL-10. In vivo, allogeneic T1 cells expanded, maintained T1 secretion, and acquired allospecificity involving IFN-gamma and IL-5. In contrast, allogeneic T2 cells expanded less and maintained T2 secretion but did not develop significant allospecificity.Allogeneic, but not syngeneic, T1 cells mediated a GVT effect against host-type breast cancer cells, as median survival time (MST) increased from 25.6 +/- 2.6 (tumor controls) to 69.2 +/- 5.9 days (P < 1.2 x 10(-9)). This T1-associated GVT effect operated independently of fasL because T1 cells from gld mice mediated tumor-free survival. In contrast, allogeneic T2 cells mediated a modest, noncurative GVT effect (MST, 29 +/- 1.3 days; P <.0019). T1 recipients had moderate GVHD (histologic score, 4 of 12) that contributed to lethality after bone marrow transplantation; in contrast, T2 recipients had minimal GVHD (histologic score, 1 of 12). CD3/CD28 co-stimulation, therefore, generates T1 or T2 populations with differential in vivo capacity for expansion to alloantigen, resulting in differential GVT effects and GVHD.

Transduction and selection of human T cells with novel CD34/thymidine kinase chimeric suicide genes for the treatment of graft-versus-host disease

Clinical trials evaluating the herpes simplex virus thymidine kinase (HSV-tk)/ganciclovir (GCV) suicide gene therapy system for the control of graft-versus-host disease (GVHD) have been limited by low transduction efficiencies and inefficient selection procedures. In this study, we designed and evaluated a novel chimeric suicide gene consisting of the extracellular and transmembrane domains of human CD34 and full-length HSV-tk (DeltaCD34-tk). High-efficiency transfer of DeltaCD34-tk to primary human T cells was accomplished after a single exposure to VSV-G-pseudotyped, Moloney murine leukemia virus-based retrovirus 48 h after activation of human PBMCs with anti-CD3 and anti-CD28 antibodies immobilized on magnetic beads. Using an optimized 5-day transduction and selection procedure, transduction efficiencies averaged 71%, with isolation purities greater than 95% and yields exceeding 90%. The immunoselected T cells were selectively eliminated by GCV (IC(50) approximately 3 nM), maintained a normal subset composition, exhibited a polyclonal TCR Vbeta family repertoire, and contained 5 or 6 vector copies per transduced cell when optimally transduced. No increase in GCV sensitivity was observed upon incorporation of highly active mutant HSV-tk enzymes into the DeltaCD34-tk suicide gene. T cells modified with the DeltaCD34-tk gene using the optimized protocol should improve the overall efficacy of the HSV-tk/GCV suicide gene therapy method of GVHD control.

Immune reactivity does not predict chemotherapy response, organ preservation, or survival in advanced laryngeal cancer

OBJECTIVE

To determine whether pretreatment lymphocyte subpopulations correlate with tumor response to induction chemotherapy as part of an organ preservation treatment approach in patients with advanced laryngeal cancer.

STUDY DESIGN

A prospective clinical trial in patients with advanced laryngeal cancer was undertaken to determine whether the frequency of late salvage laryngectomy and overall survival could be improved using one cycle of neoadjuvant chemotherapy to select patients for organ preservation. Pretreatment peripheral blood lymphocyte subpopulations for CD3, CD4, CD8, NK, and B cells were correlated with tumor response to induction chemotherapy, larynx preservation, and survival, to determine whether immune parameters could be useful in patient selection.

METHODS

The study setting was a tertiary referral academic health center. Studied were 53 patients with stage III (42%) or IV (57%) larynx cancer. Most patients had supraglottic cancers (73%) and positive clinical nodes (51%). Sixty-eight percent had greater than 50% tumor response after one cycle of induction chemotherapy and then received concurrent chemoradiation and two cycles of adjuvant chemotherapy. Lymphocyte subpopulations were measured in 39 patients. Mean follow-up was 23.3 months (range, 5-61 mo).

RESULTS

A total of 18 (34%) patients underwent laryngectomy. Only 4 cases were late salvage resections (13-35 mo after treatment). Fourteen cases were planned surgery after initial chemotherapy. Of the lymphocyte subpopulations measured, CD8 levels were significantly lower in stage IV patients and tended to be lower in patients with successful organ preservation. However, no significant differences in lymphocyte subpopulations were found among responders and nonresponders to chemotherapy. Overall survival was 88%.

CONCLUSIONS

One cycle of neoadjuvant chemotherapy was effective in selecting patients for organ preservation. The regimen of definitive concurrent and adjuvant chemotherapy was associated with an unexpectedly high 2-year survival rate. Lymphocyte subsets were not significant predictors of responding patients or survival. Further study of other biological markers useful in selecting patients for organ preservation are needed.

Clinical-scale selection of anti-CD3/CD28-activated T cells after transduction with a retroviral vector expressing herpes simplex virus thymidine kinase and truncated nerve growth factor receptor

Activation of T cells is necessary for efficient retroviral-mediated gene transfer. In addition, if the population of infused cells is to be limited to transduced cells, a means of positive selection is required. We describe a clinical scale procedure for activation of donor T cells with anti-CD3/CD28 beads followed by transduction with a retroviral construct expressing the herpes simplex virus thymidine kinase (HSV-tk) and human nerve growth factor receptor (NGFR). Optimization of transduction parameters was performed, testing the timing of transduction, centrifugation, and the use of serum. In large-scale experiments, 3-5 x 10(8) peripheral blood mononuclear cells (PBMC) were activated with anti-CD3/CD28 beads and expanded to day 13. Transduction was accomplished using MFG-TKiNG supernatant produced from the PG13 packaging line 48 hr after T-cell activation. The mean transduction frequency was 37.5% based on NGFR expression, and the mean expansion observed was 42.6-fold (mean final cell number 1.85 x 10(10)). A comparison of the ability of the Baxter Isolex 300i and the Miltenyi CliniMACS to perform purification of NGFR+ cells suggests that greater purity can be achieved with the CliniMACS device (67.4% vs. 97.7%), while the yield of transduced cells appears higher with the Isolex 300i (41.3% vs. 23.5%). We conclude that a strategy based on activation of human T cells with anti-CD3/CD28 beads can result in sufficient transduction, expansion, and purification based on NGFR expression for clinical trials.

Retrovirus-mediated gene transfer in primary T lymphocytes impairs their anti-Epstein-Barr virus potential through both culture-dependent and selection process-dependent mechanisms

To modulate alloreactivity after hematopoietic stem cell transplantation, suicide gene-expressing donor T cells can be administered with an allogeneic T-cell-depleted bone marrow graft. Immune competence of such cells is a critical issue. The impact of the ex vivo gene transfer protocol (12-day culture period including CD3/interleukin-2 [IL-2] activation, retroviral-mediated gene transfer, and G418-based selection) on the anti-Epstein-Barr virus (EBV) potential of gene-modified cells has been examined. Cytotoxic (pCTL) and helper (pTh) cell precursor limiting dilution assays, interferon-gamma enzyme-linked immunospot, or fluorescence-activated cell sorter analysis after tetrameric HLA-A2/EBV peptide complexes revealed that the frequency of anti-EBV T cells was lower in gene-modified cells (GMCs) than in similarly cultured but untransduced T cells and was even lower than in fresh peripheral blood mononuclear cells, demonstrating both an effect of the culture and of the transduction or selection. The culture-dependent loss of EBV-reactive cells resulted from the preferential induction of activation-induced cell death in tetramer(+) cells. Replacing the initial CD3/IL-2 activation by CD3/CD28/IL-2 partially restored the anti-EBV response of GMCs by reducing the initial activation-induced cell death and enhancing the proliferation of EBV-tetramer(+) cells. Moreover, the G418 selection, and not the transduction, was directly toxic to transduced tetramer(+) cells. Replacing the G418 selection by an immunomagnetic selection significantly prevented the selection-dependent loss of EBV-specific cells. Overall, ex vivo gene modification of primary T cells can result in a significant reduction in EBV-reactive T cells through both culture-dependent and selection-dependent mechanisms. Improving immune functions of GMCs through modifications of the cell culture conditions and transduction/selection processes is critical for further clinical studies.