Dendritic cell-based immunotherapy of prostate cancer: immune monitoring of a phase II clinical trial.

We assessed both non- and peptide-specific immune responses in prostate cancer patients before and after immunotherapy with dendritic cells exogenously pulsed with the prostate-specific membrane antigen-derived peptides, PSM-P1 and PSM-P2. For all subjects, we observed that clinical responses were strongly associated with two indicators of immunocompetence: skin test responses to recall antigens and cytokine secretion by T cells after nonspecific stimulation. In a subset of responders, we observed cytokine secretion or cytotoxicity against the immunizing peptides or an immunodominant epitope from an influenza recall antigen. The clinical results support the use of monitoring for overall immunocompetence to help determine why a patient has or has not responded to therapy. Moreover, it could be useful as an inclusion criterion to select those more likely to benefit from treatment.

Dendritic cell-based immunotherapy of prostate cancer.

The immunotherapy of cancer, based on eliciting or enhancing the body's own capacity to mount an effective antitumor response, has produced encouraging early results in the areas of melanoma and renal-cell carcinoma. Such treatments utilizing dendritic cells (DC), immune cells that are excellent antigen presenters, are especially promising. We performed a phase I clinical trial assessing the administration of autologous DC pulsed with HLA-A0201-specific prostate-specific membrane antigen (PSMA) for the treatment of 51 men with hormone-refractory prostate cancer. Participants were divided into five groups receiving four or five infusions of peptides alone (PSM-P1 or PSM-P2; group 1 and 2, respectively), autologous DC (group 3), or DC pulsed with PSM-P1 or P2 (group 4 and 5, respectively). No significant toxicity was observed. Immune reactivity against PSM-P2 was detected in HLA-A2+ patients infused with DC pulsed with PSM-P1 or -P2 (group 4 and 5). An average decrease in PSA was observed only in group 5. Seven partial responders were identified based on NPCP criteria + PSA. The excellent tolerance of this treatment approach, as well as the enhanced cellular responses, decreased PSA levels, and partial clinical responses in some patients suggests that it holds great potential in prostate cancer therapy.

Regulation of microglial activation by TGF-beta, IL-10, and CSF-1.

Microglia are the resident macrophages of the brain and as such are active participants in immune responses in the central nervous system. Normal resting microglia express low levels of MHC class I and class II antigens and do not produce proinflammatory cytokines. However, microglial immune functions are induced in areas of infection or injury. To understand regulation of cytokines that are secreted by and act upon microglia, we examined production of interleukin (IL) -12, tumor necrosis factor-alpha (TNF-alpha), and nitric oxide (NO) by lipopolysaccharide (LPS)-stimulated microglia. We observed secretion of IL-12, TNF-alpha, and NO following stimulation of microglia with LPS. Addition of IL-10 suppressed TNF-alpha, IL-12, and NO production. Transforming growth factor-beta (TGF-beta) also inhibited TNF-alpha and NO but did not affect IL-12 secretion. IL-12 secretion became sensitive to TGF-beta inhibition when microglia were cultured in the absence of CSF-1. In addition to its effect on the response to TGF-beta, CSF-1 suppressed the response of microglia to LPS. These data suggest that CSF-1 may contribute to the immunologically privileged status of the central nervous system.

Frequency of MBP and MBP peptide-reactive T cells in the HPRT mutant T-cell population of MS patients.

Somatic mutation as an index of in vivo T-cell amplification is a powerful tool to analyze the specificity and size of the autoreactive T-cell repertoire. Using this strategy, we determined the precursor frequency of T cells reactive to myelin basic protein (MBP) and overlapping MBP peptides spanning regions p84-168 in patients with MS and controls in the HPRT mutant T-cell population. Among 19 MS patients, nine had estimatable frequencies to MBP or MBP peptides, p93-112, p124-142 and p143-168 in the HPRT mutant T-cell population. Only one of the 10 controls showed measurable frequency to MBP in the HPRT mutant T-cell population. These studies suggest that increased frequency of T cells reactive to MBP and MBP peptides might indicate putative disease-related epitopes in MS.

T cell subset responses to allogeneic endothelium. Proliferation of CD8+ but not CD4+ lymphocytes.

Endothelial cells were isolated from the hearts of neonatal mice and cocultured with syngeneic and allogeneic lymphocytes. T cells isolated by passage through nylon wool proliferated when cultured with allogeneic endothelium but not when cultured with syngeneic endothelium. This response was almost entirely confined to the CD8+ lymphocyte subset as purified CD4+ lymphocytes displayed a minimal response. Pretreatment of endothelial cells with recombinant murine gamma interferon induced expression of Ia but did not enable endothelial cells to activate CD4+ lymphocytes. Activation of CD8+ and T lymphocytes could be blocked with monoclonal anti class I antibody but was unaffected by anti-class II antibody. The failure to activate CD4+ lymphocytes was not due to suppression and did not lead to an anergic state. Instead, coculture of CD4+ cells with allogeneic endothelial cells induced a partial activation consisting of IL-2 receptor expression and accelerated secondary response kinetics.

Vaccination with peptides from MHC class II beta chain hypervariable region causes allele-specific suppression of EAE.

In our earlier studies we showed that successful immunotherapy of EAE in SJL/J mice can be achieved either by the use of antibodies to MHC class II antigens or by vaccination with synthetic peptide analogs of the beta chain of MHC class II molecules. We proposed that inhibition of EAE following vaccination with synthetic peptides derived from the beta chain of mouse I-A, was in part due to the generation of auto-anti-MHC class II antibodies that interfered with T cell sensitization. In our present study we show that suppression of EAE following vaccination results in poor sensitization of MBP reactive T cells, and that the lack of immune response is allele-specific. In F1(SJL(I-AS) x Balb/cI-Ad) mice, in which susceptibility to EAE is linked closely to the I-AS allele, vaccination with peptides from beta chain of I-AS results in inhibition of proliferative response to MBP and prevents the development of EAE. Vaccination with peptide from the beta chain of I-Ad did not affect either the development of immune response to MBP or the induction of EAE, indicating allele-specific suppression. Since global immunosuppression is not induced by vaccination with I-A peptides, we propose that this strategy can be extended to human autoimmune diseases wherein a clear association between certain MHC class II alleles and autoimmune disease is evident.

The vascular endothelial cell is central to xenogeneic immune reactivity.

With the demand for organ transplants increasing, xenograft transplantation is being considered. A major obstacle to a solution to fulfilling this demand is xenograft rejection. Histologic evidence indicates that the vascular endothelial cell (VEC) is involved in both humoral and cellular aspects of xenograft rejection. To study this phenomenon murine VEC and splenocytes were used in a mixed lymphocyte/endothelial cell culture and in a mixed lymphocyte culture with human peripheral blood mononuclear cells as responders. The VEC is a much better stimulator than the splenocyte. Removal of macrophages and B cells from the human peripheral blood mononuclear cells has no effect on the response to the VEC. The VEC acts as a target for humoral responses in the complement-dependent cytotoxicity and the antibody-dependent cell-mediated cytotoxicity. The VEC is killed in these two assays, which indicates the importance of the VEC in humoral rejection. These data indicate that the VEC is an important cell in xenogeneic immune reaction and may be pivotal in xenograft rejection.

Cancer immunotherapy for prostate cancer.

Our approach to prostate cancer immunotherapy involves two components dendritic cells as antigen-presenting cells; and the antigen used to target T-cell attack, HLA-A0201-associated peptides from prostate specific membrane antigen (PSMA). We have conducted a phase I dose-ranging study in 51 men with advanced prostate cancer, using dendritic cells pulsed with a PSMA peptide. no significant toxicity was observed. In that study, T-cell response was enhanced, with seven men meeting NCPC and PSA criteria for partial response. We are now conducting a phase II study with 67 men, who will receive 6 infusions of dendritic cells that have been pulsed with 2 PSMA peptides, at 6-week intervals. The phase II study design and rationale is described in this paper.

Coxsackievirus B-3 myocarditis. Identification of different pathogenic mechanisms in DBA/2 and Balb/c mice.

DBA/2 and Balb/c mice, both H-2d, develop myocardial inflammation and necrosis when infected with a heart-adapted strain of coxsackievirus Group B, Type 3. Similar inoculation of C57Bl/6 (H-2b) animals results in minimal myocarditis despite equivalent heart virus titers in the three stains. Thus, the host's genetic constitution influences the pathogenesis of the infection. Anti-mouse thymocyte serum and monoclonal Iad antibody effectively prevent myocarditis induction in DBA/2 and Balb/c mice, which demonstrates the importance of the immune system in this disease. Cytolytic T lymphocytes lysing virus-infected and uninfected myocytes and heart-reactive autoantibodies occur in both myocarditis-susceptible strains. Cellular immunity causes the myocardial injury in Balb/c mice. Complement depletion of Balb/c mice using cobra venom factor fails to alter the disease. Similar treatment of DBA/2 animals abrogates inflammation and necrosis, which suggests that heart-reactive antibodies in this strain are primarily responsible for initiating myocardial damage.

Coxsackievirus B-3 myocarditis in Balb/c mice. Evidence for autoimmunity to myocyte antigens.

Male Balb/c mice inoculated with a heart-adapted variant of Coxsackievirus, group B, type 3 (Nancy) (CVB3M), develop extensive myocarditis and cytolytic activity to primary cultures of uninfected and infected myocytes. To elucidate the mechanisms of myocyte injury in myocarditis, two distinct cytolytic T-lymphocyte (CTL) populations were isolated by immunoadsorption of lymph node cells to glutaraldehyde-fixed uninfected and infected myocyte monolayers. One population preferentially adsorbed to and lysed uninfected myocytes (autoreactive CTLs), while the other adsorbed to and lysed CVB3M-infected myocytes (virus-specific CTL). Neither CTL population adsorbed to monolayers of HeLa, L929, or umbilical cord endothelial cells, or to myocytes infected with a related but nonmyocarditic Coxsackievirus B-3 variant ( CVB3o ). While both autoreactive and virus-specific CTLs induced myocarditis in vivo, the lesions caused by autoreactive CTLs were more extensive and necrotizing than those of virus-specific cells. These results support the hypothesis that CVB3 -induced myocarditis results, in part, from autoimmunity to myocyte antigens.

Use of cellular and cytokine adjuvants in the immunotherapy of cancer.

Cellular and cytokine adjuvants, often immune effector cells and soluble factors, respectively, are supplemental and/or follow-up treatments of human origin for cancer patients who have unsatisfactory clinical responses to conventional chemotherapy, radiotherapy, and surgery. Since many human studies with these reagents are in their infancy, extensive data collection is only now being performed to determine which strategy provides the greatest therapeutic benefit. Research published in the literature since the genesis of this approach to cancer treatment is summarized in this report. Methodologies attempting to generate anticancer responses by provoking or enhancing the patient's own immune system are new compared with the other standard types of cancer treatment. Although a few encouraging human studies can be discussed, many of the most promising techniques are only now being transferred from the laboratory to the clinic. The administration of immune effector cells in combination with immunomodulators, such as interferons or interleukins, often enhances clinical outcome. The literature cited in this report indicate that immune-cell- and cytokine-based therapies hold promise in our attempts to improve the quality and duration of life in those with cancer. With each report reaching the literature, more effective clinical trials are being designed and implemented.

Cardiac injury in myocarditis induced by Coxsackievirus group B, type 3 in Balb/c mice is mediated by Lyt 2 + cytolytic lymphocytes.

Male Balb/c mice inoculated with a heart-adapted variant of Coxsackievirus, group B, type 3 (CVB3) develop severe myocarditis 7 days later. The lesions are characterized by mononuclear cell inflammation and myocyte necrosis. Infected T-lymphocyte-deficient mice show either minimal or no cardiac injury, although virus concentrations in the hearts of T-cell-deficient and -sufficient animals are similar. Adoptive transfer of 2 X 10(6) CVB3 immune Thy 1+ cells into CVB3-infected T-cell-deficient mice effectively restored myocarditis to levels observed in intact animals. Similar reconstitution with immune Ig+ cells or serum resulted in only a minimal increase in cardiac injury. To determine whether T-lymphocyte-dependent humoral or cellular immunity was responsible for myocarditis. T lymphocytes were obtained from Balb/c mice 6 days after infection with CVB3, separated into Lyt 1+2- (helper) and Lyt 1-2+ (cytolytic/suppressor) cell populations, and 2 X 10(6) of the enriched helper and cytolytic cells were adoptively transfused into infected T-cell-deficient recipients. Animals receiving the immune Lyt2+ cells developed severe myocarditis, had cytolytic T lymphocytes to both CVB3-infected and uninfected myocytes, but lacked a detectable IgG antibody response. Recipients of the Lyt 1+ cells failed to develop either myocarditis or cytolytic T cells but had normal serum IgG antibody titers to the virus. These results demonstrate that cardiac myocarditis is the product of cellular immune mechanisms.

Myelin basic protein peptide specificity and T-cell receptor gene usage of HPRT mutant T-cell clones in patients with multiple sclerosis.

Characterization of T cells responding to autoantigens is central to understanding autoimmune disease. We have used somatic mutation at the hypoxanthine guanine phosphoribosyltransferase (HPRT) gene as an index of T-cell amplification in vivo. With this strategy we previously showed that myelin basic protein-reactive T cells can be isolated only from the HPRT mutant T-cell population cultured from the peripheral blood of multiple sclerosis patients and not from normal individuals. In this study, 165 HPRT mutant and 104 wild-type clones were examined for their reactivity to myelin basic protein and overlapping peptides of myelin basic protein. Five HPRT mutant clones that recognized myelin basic protein and myelin basic protein peptides along with three clones that responded to myelin basic protein peptide alone were isolated. All but one of the eight clones recognized peptides derived from the carboxy terminus of myelin basic protein (p84-168). Sequence analysis showed heterogeneous expression of T-cell receptor V alpha and V beta genes and CDR3s. These studies showed that in vivo amplified autoimmune T cells from patients with long-standing disease use diverse T-cell receptor elements in the recognition of C-terminal myelin basic protein peptides.

Immunopathogenesis of experimental Coxsackievirus induced myocarditis: role of autoimmunity.

The pathogenesis of cardiac injury in clinical myocarditis is unknown. Despite the association of the disease with recent viral infections, it is now assumed that immune rather than viral mechanisms are primarily responsible for myocyte destruction. Nonetheless, immunosuppressive therapy has not been universally effective in limiting myocardial damage. To better understand the mechanisms by which viral infections of the heart induce myocarditis, it has been necessary to resort to a murine model of the disease. When inbred Balb/c mice are infected with a cardiotropic variant of Coxsackievirus, group B, type 3 (CVB 3), the animals develop extensive interstitial and focal inflammatory cell infiltration of the heart similar to the lesions in humans. As in humans, a number of factors influence the severity of the disease. Males develop severe myocarditis while virgin females are generally protected. Female resistance does not persist during pregnancy, however, when resultant myocarditis is frequently worse than that observed in males. The susceptibility of males and pregnant females results from the influence of testosterone and progesterone on the immune response. Susceptible animals generate autoimmune cytolytic T lymphocytes which recognize normal myocyte cell surface antigens and are responsible for most of the cardiac damage in experimental myocarditis. Virgin females do not develop significant myocarditis apparently because the estrogens enhance suppressor cells which prevent the autoimmune T cell generation. Humoral (antibody-mediated) immunity to the heart antigens is also present, but apparently has no role in the pathogenesis of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional diversity in vascular endothelial cells: role in coxsackievirus tropism.

Six plaque-purified virus isolates were obtained from liver and heart tissues of a DBA/2 mouse infected 7 days earlier with 10(4) PFU of coxsackievirus group B type 3. Each virus isolate was assayed in vitro for infectivity to vascular endothelial cells (VEC) of the liver, lungs, and heart. Both the percentage of VEC infected and the mean progeny PFU produced per infected VEC were determined. Virus isolates from the heart showed greater infectivity and replication in heart VEC than in VEC derived from either the liver or lungs. Similarly, virus isolated from the liver preferentially infected liver VEC. Virus receptor expression varied between VEC populations, as demonstrated by binding studies with a [35S]methionine-radiolabeled heart virus and by enzyme-linked immunoadsorption assay studies with a monoclonal antibody to the coxsackievirus group B type 3 receptor on heart tissue. Finally, the heart and liver virus isolates were injected (10(4) PFU) intraperitoneally into BALB/c mice. After 7 days, the animals were sacrificed, and the hearts, livers, and lungs were evaluated for tissue injury and virus concentrations. Viruses originally isolated from the heart preferentially infected the heart when reinjected into animals and caused severe myocarditis. Viruses originally derived from the liver most consistently reinfected the liver, although significant virus concentrations were also detected in the heart. The liver virus isolates, however, were incapable of causing myocarditis. Thus, selective tropism of viruses for particular organs in vivo corresponds to the ability of these isolates to infect VEC in vitro.