Infusion Of Dendritic Cells Research Articles

Immunosuppressive and Trafficking Properties of Donor Splenic and Bone Marrow Dendritic Cells

Infusion of donor dendritic cells (DC) has been shown to prolong allograft survival in a number of models. However, many regimens that utilize donor DC do not consistently produced tolerance or long-term allograft survival. We hypothesized that one factor limiting the therapeutic effect of donor DC is their relative inability to traffic to recipient peripheral lymph nodes and inhibit the function of resident alloreactive T cells. Donor strain DC isolated from the spleens or bone marrow of Flt3L-treated mice were transferred intravenously into recipients at the time of skin grafting. Where indicated, recipients were treated with an anti-CD40L antibody and CTLA4-Ig. Infusion of donor DC together with costimulatory blockade promoted donor-specific prolongation of skin allograft survival in mice. Perhaps due to their more immature phenotype, bone marrow DC trafficked more effectively to the spleen, bone marrow, and thymus and were associated with significantly longer allograft survival than were splenic DC. Neither population of DC trafficked well to peripheral lymph nodes. Consistent with our hypothesis, splenic but not lymph node T cells from DC-treated recipients displayed donor-specific hyporesponsiveness in vitro. These data suggest that one factor contributing to rejection following treatment with donor DC plus costimulation blockade is the persistence of donor-reactive T cells within the recipient's secondary lymphoid structures. Strategies to improve DC trafficking to these structures may enhance their therapeutic effect.

Efficacy of dendritic cell infusion in advanced hepatocellular carcinoma

4168 Background: Some studies demonstrated that dentritic cell immunotherapy is positive effective therapy in melanoma and prostate cancer. We conducted a pilot study to evaluate the effect of dendritic cell infusion applying in advanced hepatocellular carcinoma. Methods: The 21 patients with hepatocellular carcinoma received chemotherapy and G-CSF used to mobilize peripheral blood hematopoietic stem cell. CD34+ stem cell were induced to differentiate into dendritic cell by cytokines IL-4, GM-CSF, and TNF-a. After cultured for 7 days, dendritic cell were infused into patient’s vein or directly injected into tumors tissue once a week over a 3 week. The response rate, Karnofsky score, AFP and HBV virus copy were checked before and after infusion or injection. Results: The response rate including SD rate is 76%, the tumor shrink demonstrate in 2 patients. Karnofsky score increases in 15 patients. Both the AFP and HBV virus copies decreased, a significant reduction (t=0.014) in AFP serum lever was found. No severe side-effects were found except for diarrhea in 1 patient, fever in 3 patients and liver pain in 2 patients after directly injection into tumor. Conclusions: Dendritc cell immunotherapy is of promising to treat advanced hepatocellular carcinoma without severe side effect. In order to get stronger immune response, loading tumor specialized antigen is crucial. No significant financial relationships to disclose.

Promotion of Long-Term Heart Allograft Survival by Combination of Mobilized Donor Plasmacytoid Dendritic Cells and Anti-CD154 Monoclonal Antibody

Infusion of donor immature dendritic cells (DC) can significantly prolong survival of organ allografts, and this is believed to be due to antigen recognition by T cells in the absence of co-stimulation. In this study we report that a single pre-operative infusion of donor-mobilized immature plasmacytoid dendritic cells (pDCs) is superior to that of other DC sub-sets in suppressing allograft rejection. The combination of pDC infusion with injection of anti-CD154 monoclonal antibody further inhibited graft rejection and, in 50% of the mice, led to indefinite graft survival. This finding suggests a role for the plasmacytoid DC sub-set in facilitating organ transplant survival and also in the treatment of autoimmune disorders.

Immunity toAspergillus fumigatus: the basis for immunotherapy and vaccination

Efficient responses to fungi require different mechanisms of immunity. Dendritic cells (DCs) are uniquely able to decode the fungus-associated information and translate it into qualitatively different T helper (Th) immune responses. Murine and human DCs phagocytose conidia and hyphae of Aspergillus fumigatus through distinct recognition receptors. The engagement of distinct receptors translates into disparate downstream signaling events, ultimately affecting cytokine production and co-stimulation. Adoptive transfer of different types of DCs activates protective and non-protective Th cells as well as regulatory T cells, ultimately affecting the outcome of the infection in mice with invasive aspergillosis. The infusion of fungus-pulsed or RNA-transfected DCs also accelerates recovery of functional antifungal Th 1 responses in mice with allogeneic hematopoietic stem cell transplantation. Patients receiving T cell-depleted allogeneic hematopoietic stem cell transplantation are unable to develop antigen-specific T cell responses soon after transplant due to defective DC functions. Our results suggest that the adoptive transfer of DCs may restore immunocompetence in hematopoietic stem cell transplantation by contributing to the educational program of T cells. Thus, the remarkable furictional plasticity of DCs can be exploited for the deliberate targeting of cells and pathways of cell-mediated immunity in response to the fungus.

Comparative analysis of the fate of donor dendritic cells and B cells and their influence on alloreactive T cell responses under tacrolimus immunosuppression

We have shown that tacrolimus (TAC)-induced liver allograft acceptance is associated with migration and persistence of donor B cells and dendritic cells (DC). To clarify whether these MHC class II + leukocytes have favorable roles in inducing tolerance, we analyzed recipient T cell reactions after allogeneic B or DC infusion. LEW rat B cells localized exclusively in BN host B cell follicles without any direct contact with host T cells. While few donor DC migrated to T cell areas and marginal zones, they were captured by host APC, suggesting that allogeneic MHC class II + cells may induce immune reactions via the indirect pathway. Although DC-infused non-immunosuppressed recipients showed enhanced ex vivo anti-donor responses, persistent in vitro donor-specific hyporeactivity was seen equally with donor DC or B cell infusion under TAC. The results indicate that donor MHC class II + APC are capable of regulating recipient immune reactions under TAC. Possible involvement of the indirect pathway of allorecognition is discussed.

Prospects for Dendritic Cell Vaccination Against Fungal Infections in Hematopoietic Transplantation.

Dendritic cells (DCs) are uniquely able to initiate and control the immune response to fungi. DCs function at three levels in the manipulation of the immune response to these pathogens: 1) they mount an immediate or innate response to them, for example by producing inflammatory mediators upon capture and phagocytosis; 2) through these preceding innate functions, they decode the fungus-associated information and translate it in qualitatively different Th responses; 3) and they are key in containing and dampening inflammatory responses by tolerization through the induction of regulatory T cells (Treg). We demonstrated that both murine and human DCs sense fungi in a morphotype-specific manner, through the engagement of distinct recognition receptors ultimately affecting cytokine production and costimulation (Romani et al. Int Immunol. 2003). In this study we analyzed both myeloid and plasmacytoid murine and human DCs and we observed that they phagocytose fungi and undergo functional maturation in response to them. However, their activation program for cytokine production was different, being IL-12 mainly produced by myeloid DCs and IL-12, IL-10 and IFN-gamma mainly produced by plasmacytoid DCs. This resulted in a distinct ability for T-cell priming, being Th1, Th2 and Treg differently activated by the different DC subsets. The ability of fungus-pulsed DCs to prime for Th1, and Th2 cell activation upon adoptive transfer in vivo correlated with the occurrence of resistance and susceptibility to the infections, respectively. Antifungal protective immunity was also induced upon adoptive transfer of DCs transfected with fungal RNA (Bacci et al. J Immunol. 2002; Bozza et al. Blood. 2003). The efficacy was restricted to DCs transfected with RNA from yeasts or conidia but not with RNA from fungal hyphae. The effect was fungus-specific, as no cross-protection was observed upon adoptive transfer of DCs pulsed with either fungal species. The infusion of fungus-pulsed or RNA-transfected DCs accelerated the recovery of functional antifungal Th1 responses in mice with allogeneic hematopoietic stem cell transplantation (HSCT) without triggering graft-versus-host disease (GvHD) and affected the outcome of the infections. As the ability to respond to fungi was defective in peripheral DCs from patients with HSCT in terms of phagocytosis, cytokine production, and donor T-cell priming, our findings suggest that the adoptive transfer of DCs may restore immunocompetence in HSCT by contributing to the educational program of T-cells. Thus, the remarkable functional plasticity of DCs in response to fungi can be exploited for the deliberate targeting of cells and pathways of cell-mediated immunity in response to fungal vaccines.

Prospects for dendritic cell vaccination against fungal infections in hematopoietic transplantation

Dendritic cells (DCs) are uniquely able to initiate and control the immune response to fungi. DCs function at three levels in the manipulation of the immune response to these pathogens. First, they mount an immediate or innate response to them, for example, by producing inflammatory mediators upon capture and phagocytosis; second, through these preceding innate functions, they decode the fungus-associated information and translate it in qualitatively different Th responses, and third, they are key in containing and dampening inflammatory responses by tolerization through the induction of regulatory T cells (Treg). DCs sense fungi in a morphotype-specific manner, through the engagement of distinct recognition receptors ultimately affecting cytokine production and costimulation. Both myeloid and plasmacytoid murine and human DCs phagocytose fungi and undergo functional maturation in response to them. However, their activation program for cytokine production was different, being IL-12 mainly produced by myeloid DCs and IL-12, IL-10 and IFN-α mainly produced by plasmacytoid DCs. This resulted in a distinct ability for T cell priming, being Th1, Th2, and Treg differently activated by the different DC subsets. The ability of fungus-pulsed DCs to prime for Th1 and Th2 cell activation upon adoptive transfer in vivo correlated with the occurrence of resistance and susceptibility to the infections, respectively. Antifungal protective immunity was also induced upon adoptive transfer of DCs transfected with fungal RNA. The efficacy was restricted to DCs transfected with RNA from yeasts or conidia but not with RNA from fungal hyphae. The effect was fungus-specific, as no cross-protection was observed upon adoptive transfer of DCs pulsed with either fungal species. The infusion of fungus-pulsed or RNA-transfected DCs accelerated the recovery of functional antifungal Th1 responses in mice with allogeneic hematopoietic stem cell transplantation (HSCT) and affected the outcome of the infections. As the ability of phagocytose fungi was defective in peripheral DCs from patients with HSCT, soon after the transplant, our findings suggest that the adoptive transfer of DCs may restore immunocompetence in HSCT by contributing to the educational program of T cells. Thus, the remarkable functional plasticity of DCs in response to fungi can be exploited for the deliberate targeting of cells and pathways of cell-mediated immunity in response to fungal vaccines.

Effective induction of immune tolerance by portal venous infusion with IL-10 gene-modified immature dendritic cells leading to prolongation of allograft survival.

Dendritic cells (DC) not only initiate T cell responses, but are also involved in the induction of tolerance. The functional properties of DC are strictly dependent on their state of maturation. It has been shown that immature DC can induce immune tolerance and prolong allograft survival. Interleukin-10 (IL-10) is an important immunosuppressive cytokine which inhibits maturation and function of DC. In order to improve the tolerogenicity of DC, we and others showed that adenovirus vectors can effectively mediate IL-10 genetic modification of DC, and IL-10 genetic modification can inhibit MHC II, B7.2, and CD40 expression, IL-12 secretion and the T cell stimulatory capacity of DC. The primary aim of this study is to examine the in vivo effects of this approach on allograft survival in a murine cardiac allograft transplantation model. To our surprise,we observed that infusion of immature DC genetically modified to express IL-10 (DC-IL-10) via the tail vein could not prolong allograft survival in the recipients, but shortened their survival. More interestingly, portal venous infusion of DC-IL-10 markedly prolonged allograft survival. The diverse effects of DC-IL-10 infusion through different routes may be due to the different immune responses to alloantigens in recipients that received DC-IL-10 via either the portal or the tail vein. Decreased cytotoxicity, polarization of Th2 response, poor T cell stimulating activity of liver DC and enhanced incidence of donor DC in the recipients may contribute to the more efficient prolongation of allograft survival observed after portal venous infusion of DC-IL-10. These results suggest that portal venous infusion may be an effective approach for immature DC to induce immune tolerance or hyporesponsiveness against donor antigens, and prolong allograft survival.

The Evolving Role of Monoclonal Antibodies and Dendritic Cell Therapy in Hematologic Malignancies

The approach for treatment of hematological cancers had changed in the last decade from non-specific eradication of tumor cells by chemotherapy to more specific strategies by activation of immune system.There are number of potential targets of immune responses in patients with hematological malignancies. Some have been developed like monoclonal antibody therapy and others that have yet to be define like dendritic cell infusion.In this review, we will discuss the evolving role of monoclonal antibody therapy and donor dendritic cell infusion in mounting on immune response in hematological malignancies.

Idiotype vaccination using dendritic cells after autologous peripheral blood progenitor cell transplantation for multiple myeloma

The idiotype (Id) determinants on the multiple myeloma immunoglobulin can serve as tumor-specific antigens. An anti-Id immune response may stem the growth of the malignant clone. We report on 26 patients treated at our institution with high-dose chemotherapy and peripheral blood progenitor cell transplantation (PBPCT) and vaccinated with the Id protein. The patients received chemotherapy and PBPCT to establish a minimal residual disease state. After high-dose therapy, the patients received a series of monthly immunizations consisting of 2 intravenous infusions of dendritic cells (DCs) pulsed with either Id protein or Id coupled with keyhole limpet hemocyanin (KLH) as an immunogenic carrier protein, followed by subcutaneous boosts of Id-KLH conjugates. DCs were obtained in all patients from a leukapheresis product 3 to 9 months after PBPCT. Patients were observed for toxicity, immune responses, and tumor status. The DC infusions and the administration of Id-KLH boosts were well tolerated, with patients experiencing only minor and transient side effects. Of the patients, 24 of 26 generated a KLH-specific cellular proliferative immune response. Only 4 patients developed an Id-specific proliferative immune response. Three of these immune responders were in complete remission at the time of vaccination. A total of 17 patients are alive at a median follow-up of 30 months after transplantation. Id vaccination with autologous DCs is feasible for myeloma patients after transplantation. Id-specific cellular responses can be induced in patients who are in complete remission. Further studies are needed to increase the rate of anti-Id immune responses in patients who do not achieve complete remission. Biol Blood Marrow Transplant 2000;6(6):621-7.

Regulation of Gene Expression of Murine MD-1 Regulates Subsequent T Cell Activation and Cytokine Production

The immunoadhesin (OX2:Fc) comprising the extracellular domain of murine OX2 linked to IgG2aFc, inhibits production of IL-2 and IFN-gamma by activated T cells and increases allograft and xenograft survival in vivo. Increased expression of OX2 on dendritic cells (DC) in vivo following preimmunization via the portal vein is also associated with elevated expression of MD-1. We have used antisense oligodeoxynucleotides (ODNs) to MD-1 to investigate the effect of inhibition of expression of MD-1 by DC on their function as allostimulatory cells. We also investigated by FACS analysis the cell surface expression of OX2, CD80, and CD86 on DC incubated with ODN-1 blocking MD-1 expression. Blocking MD-1 gene expression inhibits surface expression of CD80 and CD86, but not of OX2. DC incubated with ODN-1 to MD-1 did not stimulate IL-2 or IFN-gamma production, but generated cells able to suppress, in a second culture of fresh DC plus allogeneic T cells, production of IL-2 and IFN-gamma. This inhibition was blocked by anti-OX2 mAb. Infusion of DC preincubated with ODN-1 prolonged renal allograft survival, an effect also reversed by anti-OX2 mAb. By FACS, incubation of DC with anti-MD-1 Ab to promote capping eliminated cell surface expression of MD-1 and CD14 without altering DEC205, DC26, CD80, CD86, or OX2 expression. Thus OX2 and MD-1 are independent surface molecules on DC that may reciprocally regulate T cell stimulation. MD-1 is linked to CD14, a "danger receptor complex," and activation of this complex can regulate cell surface expression of CD80/CD86, which signal T cells.

Synergy in induction of increased renal allograft survival after portal vein infusion of dendritic cells transduced to express TGFbeta and IL-10, along with administration of CHO cells expressing the regulatory molecule OX-2.

Dendritic cells (DC), generated from C57BL/6 mouse bone marrow cells cultured with GM-CSF and IL-4 for 9 days, were engineered to express constitutively the cytokines TGFbeta, IL-10, and IL-12, using adenovirus vectors constructed using an E1-deleted replication-deficient recombinant adenovirus carrying the appropriate cDNA for the relevant cytokines (Ad-TGFbeta, Ad-IL-12, or Ad-IL-10). C3H mice receiving nontransduced DC or pretransplant infusion of DC-Ad-LacZ showed increased survival of C57BL/6 renal grafts relative to that of control nonimmunized mice. Transfusion of Ad-IL-12-transduced DC abolished this increased survival, leading to a graft survival equivalent to that of controls with no DC. Optimal graft survival was seen in the group receiving a mixture of DC transduced with constructs for both IL-10 and TGFbeta. There was a correlation between increased graft survival and both inhibition of the induction of CTL and enhancement of a polarization to produce type-2 cytokines (IL-4, IL-10, and TGFbeta) on antigen-specific restimulation in vitro. These effects were more pronounced following concomitant infusion of CHO cells transfected with a full-length cDNA for murine OX-2.

In Vivo Persistence of Donor Cells following Adoptive Transfer of Allogeneic Dendritic Cells in HIV-Infected Patients.

Peripheral blood samples from HIV-seropositive individuals enrolled in a pilot clinical trial investigating the use of allogeneic dendritic cell therapy were evaluated for mixed chimerism. In this study, dendritic cells from HLA-identical, HIV-seronegative siblings were used. Patients received an infusion of dendritic cells pulsed with HIV MN gp160 protein or with peptides from HLA-A2 restricted epitopes of env, gag, and pol proteins every month for 6-9 months. Of the five allogeneic dendritic cell recipients, two showed increases in HIV antigen-specific immune responses. Allele-specific polymorphisms were identified in three sib-pairs that allowed infused donor cells to be detected using sensitive PCR-based molecular methods. Analysis of blood samples from patients showed similar patterns of donor cell persistence after the first infusion, in that cells were detectable for at least 1 week. Also, differences were observed in the kinetics of cell survival between the first and subsequent infusion cycles in all three patients. This suggests variation in HIV-specific immune responses detected among these three patients was not due to differences in persistence of infused donor cells.

Use of artificial neural networks in evaluating prognostic factors determining the response to dendritic cells pulsed with PSMA peptides in prostate cancer patients.

Our purpose was to compare the importance of over 22 measurements used in evaluating the clinical responses of patients with metastatic or locally recurrent prostate cancer, treated by dendritic cell (DC) infusions with prostate-specific membrane antigen (PSMA) peptides. Artificial neural networks (ANNs) were employed for assessment, as well as the traditional methods of logistic regression. Twenty-six patients with metastatic disease and 37 patients with local recurrence were available for evaluation and comparison. ANN evaluation ranked the collective effects of DC infusion, immune responses (CD3+ cells, CD16+ cells, zeta chain+ cells), and cytokines, e.g., IL-6 and PSMA levels, very highly. Logistic regression identified all of these parameters to some degree, but in a different rank order. Patients with metastases showed a sharp rate of response secondary to the level of DC infusion, in contrast to those patients with local recurrence, in which it was more gradual. ANN analysis emphasizes the importance of level of DC infusion, immune parameters, cytokines, and markers such as PSMA in determining the response to PSMA peptide immunotherapy. The criteria of response were judged to be correct in 86% of metastatic patients and 83% of locally recurrent patients evaluated in this study.

Idiotype Vaccination Using Dendritic Cells After Autologous Peripheral Blood Stem Cell Transplantation for Multiple Myeloma—A Feasibility Study

The idiotype (Id) determinant on the multiple myeloma (MM) protein can be regarded as a tumor-specific marker. Immunotherapy directed at the MM Id may stem the progression of this disease. We report here on the first 12 MM patients treated at our institution with high-dose therapy and peripheral blood stem cell transplantation (PBSCT) followed by Id immunizations. MM patients received PBSCT to eradicate the majority of the disease. PBSCT produced a complete response in 2 patients, a partial response in 9 patients and stable disease in 1 patient. Three to 7 months after high-dose therapy, patients received a series of monthly immunizations that consisted of two intravenous infusions of Id-pulsed autologous dendritic cells (DC) followed by five subcutaneous boosts of Id/keyhole limpet hemocyanin (KLH) administered with adjuvant. Between 1 and 11 × 106 DC were obtained by leukapheresis in all patients even after PBSCT. The administration of Id-pulsed DC and Id/KLH vaccines were well tolerated with patients experiencing only minor and transient side effects. Two of 12 patients developed an Id-specific, cellular proliferative immune response and one of three patients studied developed a transient but Id-specific cytotoxic T-cell (CTL) response. Eleven of the 12 patients generated strong KLH-specific cellular proliferative immune responses showing the patients’ immunocompetence at the time of vaccination. The two patients who developed a cellular Id-specific immune response remain in complete remission. Of the 12 treated patients, 9 are currently alive after autologous transplantation with a minimum follow-up of 16 months, 2 patients died because of recurrent MM and 1 patient succumbed to acute leukemia. These studies show that patients make strong anti-KLH responses despite recent high-dose therapy and that DC-based Id vaccination is feasible after PBSCT and can induce Id-specific T-cell responses. Further vaccine development is necessary to increase the proportion of patients that make Id-specific immune responses. The clinical benefits of Id vaccination in MM remain to be determined.

Idiotype Vaccination Using Dendritic Cells After Autologous Peripheral Blood Stem Cell Transplantation for Multiple Myeloma—A Feasibility Study

AbstractThe idiotype (Id) determinant on the multiple myeloma (MM) protein can be regarded as a tumor-specific marker. Immunotherapy directed at the MM Id may stem the progression of this disease. We report here on the first 12 MM patients treated at our institution with high-dose therapy and peripheral blood stem cell transplantation (PBSCT) followed by Id immunizations. MM patients received PBSCT to eradicate the majority of the disease. PBSCT produced a complete response in 2 patients, a partial response in 9 patients and stable disease in 1 patient. Three to 7 months after high-dose therapy, patients received a series of monthly immunizations that consisted of two intravenous infusions of Id-pulsed autologous dendritic cells (DC) followed by five subcutaneous boosts of Id/keyhole limpet hemocyanin (KLH) administered with adjuvant. Between 1 and 11 × 106 DC were obtained by leukapheresis in all patients even after PBSCT. The administration of Id-pulsed DC and Id/KLH vaccines were well tolerated with patients experiencing only minor and transient side effects. Two of 12 patients developed an Id-specific, cellular proliferative immune response and one of three patients studied developed a transient but Id-specific cytotoxic T-cell (CTL) response. Eleven of the 12 patients generated strong KLH-specific cellular proliferative immune responses showing the patients' immunocompetence at the time of vaccination. The two patients who developed a cellular Id-specific immune response remain in complete remission. Of the 12 treated patients, 9 are currently alive after autologous transplantation with a minimum follow-up of 16 months, 2 patients died because of recurrent MM and 1 patient succumbed to acute leukemia. These studies show that patients make strong anti-KLH responses despite recent high-dose therapy and that DC-based Id vaccination is feasible after PBSCT and can induce Id-specific T-cell responses. Further vaccine development is necessary to increase the proportion of patients that make Id-specific immune responses. The clinical benefits of Id vaccination in MM remain to be determined.

Infusion of dendritic cells pulsed with HLA‐A2‐specific prostate‐specific membrane antigen peptides: A phase II prostate cancer vaccine trial involving patients with hormone‐refractory metastatic disease

Infusion of dendritic cells pulsed with HLA‐A2‐specific prostate‐specific membrane antigen peptides: A phase II prostate cancer vaccine trial involving patients with hormone‐refractory metastatic disease

Differential Regulation of Rejection of Small Intestinal and Skin Allografts in Rats by Injection of Antibodies to ICAM-1 or the Integrins α4, αL, or β2

Female Lewis (LEW) rats received orthotopic small intestinal transplantation (SIT), or tail skin grafts from female (Lewis × Brown Norway)F1 (LBNF1) rats, along with peritransplant portal venous (pv) infusion of LBNF1 bone marrow-derived dendritic cells derived from male donors. All animals received im injection with cyclosporin A (5 mg/kg) for 3 consecutive days following transplantation. In some cases rats received intravenous injections, at 2-day intervals, with 1 mg of monoclonal antibodies to ICAM-1 or the integrins α4, αL, or β2, or combinations of these reagents. Cells were harvested from the recipient rats at different times posttransplantation, and single cell suspensions were analyzed by FACS for expression of CD3+, CD4+, CD8+, αβTcR+, and γδTcR+cells. Other tissue samples were used for histopathological assessment of rejection. We also investigated donor-specific and third-party (Wistar–Furth, Wi) restimulation of host lymphocytes from MLN, PLN, and PP for production of different cytokinesin vitro.Of the various antibodies tested, only anti-α4, but not anti-αL, -β2, nor -ICAM-1 led to further increased graft survival of LBNF1 SIT beyond that seen with pv-infused cells alone (30 days vs 19 days), while the combination of anti-αL(or β2) and ICAM-1 produced further significantly increased survival of skin grafts (30 days vs 21 days). For both SIT and skin-grafted animals increased graft survival was associated with decreased production of IL-2 and IFN-γ and increased production of IL-4 and IL-10 from tissues local to the graft (PP and draining LN, respectively), with less significant alterations in tissues distant to the graft (PLN for SIT, and MLN for skin grafts). While, as reported previously, pv-immunized SIT rats showed increased γδTCR+cells within the SIT in association with increased graft survival, treatment with anti-α4diminished this increase in γδTCR+cells, while simultaneously increasing SIT survival. Nevertheless, the bias toward increased IL-10 production, and decreased IFN-γ production, from cells of animals showing increased survival was maintained. These data suggest that local graft infiltration with γδTCR+cells following pv immunization is not necessary for prolongation of survival in this model system, although functional changes in the local cytokine milieu may be important.

Generation of Primary Peptide-Specific CD8 Cytotoxic T-Lymphocytes In Vitro Using Allogeneic Dendritic Cells

Dendritic cells (DC) are potent antigen-presenting cells (APC) capable of inducing strong T-cell–mediated immunity. Infusion of lymphoma-specific antigen-loaded autologous DC has been demonstrated to result in the generation of antigen-specific immunity and reduction in tumor burden in B-cell lymphoma patients. Cellular immunotherapy employing antigen-loaded DC could have a potential therapeutic impact in tumors and viral infections, including HIV infection. However, DC in HIV-infected individuals and breast cancer patients are believed to be functionally defective. Therefore, the potential of using allogeneic DC offers significant implications for DC immunotherapy in AIDS and immunocompromised cancer patients. To explore the potential of allogeneic DC therapy in vivo, we tested the ability of allogeneic DC to generate primary peptide-specific CD8 + cytotoxic T-lymphocyte (CTL) responses in vitro. Our results indicate that DC from HLA class I-matched individuals elicit primary immune responses in vitro using viral peptides as naive antigens. A primary peptide-specific immune response could also be detected even when only one HLA allele (HLA-A∗0201) was matched between the allogeneic DC and T-lymphocytes. The ability to generate primary peptide-specific responses in vitro is strongly indicative of the in vivo therapeutic potential of allogeneic DC.

Generation of primary peptide-specific CD8+ cytotoxic T-lymphocytes in vitro using allogeneic dendritic cells.

Dendritic cells (DC) are potent antigen-presenting cells (APC) capable of inducing strong T-cell-mediated immunity. Infusion of lymphoma-specific antigen-loaded autologous DC has been demonstrated to result in the generation of antigen-specific immunity and reduction in tumor burden in B-cell lymphoma patients. Cellular immunotherapy employing antigen-loaded DC could have a potential therapeutic impact in tumors and viral infections, including HIV infection. However, DC in HIV-infected individuals and breast cancer patients are believed to be functionally defective. Therefore, the potential of using allogeneic DC offers significant implications for DC immunotherapy in AIDS and immunocompromised cancer patients. To explore the potential of allogeneic DC therapy in vivo, we tested the ability of allogeneic DC to generate primary peptide-specific CD8+ cytotoxic T-lymphocyte (CTL) responses in vitro. Our results indicate that DC from HLA class I-matched individuals elicit primary immune responses in vitro using viral peptides as naive antigens. A primary peptide-specific immune response could also be detected even when only one HLA allele (HLA-A*0201) was matched between the allogeneic DC and T-lymphocytes. The ability to generate primary peptide-specific responses in vitro is strongly indicative of the in vivo therapeutic potential of allogeneic DC.