The lack of any detectable JCV CTL expansion in lymphocytes of 4 HC and 1 PML patient could be explained by an immune response directed toward other JCV epitopes or by a very low frequency of JCV epitope-specific CTL response in fresh blood

The lack of any detectable JCV CTL expansion in lymphocytes of 4 HC and 1 PML patient could be explained by an immune response directed toward other JCV epitopes or by a very low frequency of JCV epitope-specific CTL response in fresh blood. Rabbit Polyclonal to DHRS2 2006) which occurs in up to 5% of people with AIDS (Antinori et al., 2003), as well as in patients with lymphoproliferative disorders, organ transplant recipients and individuals treated with natalizumab (Berger and Koralnik, 2005). After asymptomatic primary infection, JCV remains quiescent in the kidney, and can be found in urine of 30% of healthy and immunosuppressed individuals alike (Koralnik et al., 1999) and in lymphoid organs (Monaco et al., 1998). In immunocompromised individuals, JCV may reactivate from sites of latency and causes a lytic infection of oligodendrocytes leading to multiple areas of demyelination in the central nervous system, and ultimately death within a few months. There is no effective treatment for this disease and those patients who survive are often left with devastating neurological sequellae (De Luca et al., 1998). Therefore, a therapeutic vaccine may contain JCV replication, especially in the early stage of the disease, and may reduce the morbidity and mortality in patients with PML. The antibody response to JCV is unable to prevent development of PML or prevent disease progression (Weber et al, 1997). Conversely, the cellular immune response mediated by JCV-specific CD8+cytotoxic T-lympocytes (CTL) plays a crucial role in the containment of PML (Du Pasquier et al., 2003;Du Pasquier et al., 2004;Koralnik et al., 2002). Hence, a Isomalt treatment that improves the CTL response against JCV may be of benefit in patients with PML. Such therapies may consist of adoptive transfer of T cells afterex vivostimulation with JCV antigens or dendritic cells (DC)-based immunotherapy (June, 2007;O’Neill and Bhardwaj, 2005). DC are the professional antigen-presenting cells in the body. A small number of DC and low level of antigens are able to induce a potent CD8+T-cell responsein vitroandin vivo(Adams et al., 2005). In addition, the safety of DC immunization has been established in numerous clinical trials (Dhodapkar and Bhardwaj, 2000). Furthermore, promising trials of DC vaccination have already been reported in patients with HIV infection (Lu et al., 2004). The frequency of JCV-specific CTL in fresh blood is very low, and their function cannot usually be measuredex vivoby conventional assays without prior stimulation with JCV antigens (Lima et al., 2007). In our quest for a treatment for PML, we first developed a DC-based stimulation of JCV-specific T cells. Then, to determine the respective potential of autologous transfer of T cells and DC-based immunotherapy for PML, we compared the CTL response elicitedin vitrofrom peripheral blood lymphocytes against JCV CTL epitopes by direct peptide stimulation, as performed in adoptive transfer of T cells, and by JCV-peptide loaded mature monocyte-derived DC. == Results == Peripheral blood samples were obtained from 20 JCV seropositive HLA-A*0201+subjects, including 6 with PML(5 HIV+and 1 HIV-) aged 40 to 69 years(47.8 12.1 years [mean SD]), 4 HIV+individuals aged 44 to 50 years(45.5 3 years) and 10 healthy controls(HC) aged 24 to 44(34 8 years). HIV+/PML and HIV+patients had a mean CD4+T cell count of 521 /L 289 and 496 /L 320 respectively, and a plasma HIV RNA level of 1.25 log10copies/ml 0.5 and 1.98 log10copies/ml 1.9, respectively. All HIV+and HIV+PML patients were on highly active antiretroviral therapy (HAART). All but one PML patients were still alive an average of 9.2 years (3.4 to 15.2 years) after disease onset. JCV-specific CTL responses against VP1p36and/or VP1p100epitopes, were detected in 14/20 study subjects, including 5/6 PML Isomalt patients, 3/4 HIV+individuals and 6/10 HC after direct peptide stimulation of lymphocytes. These responses were enhanced using peptide-loaded DC stimulation in 14/16 comparisons performed in these 14 individuals (Table 1). The average amplification factor of JCV-specific CD8+T-cell response using peptide-loaded DC compared Isomalt to peptide stimulation alone was 6.8x for PML patients, 3.9x for HIV+patients, and 31.0x for HC. Furthermore, we measured a JCV epitope-specific CTL response after DC stimulation in 1 HIV+individual (#1, VP1p100) and 2 HC (#3, VP1p100and #9, VP1p36) who had no detectable CTL after stimulation of lymphocytes with peptide alone The median percentage of JCV-specific CD8+T-cells.