The role of parvovirus B19 and the immune response in the pathogenesis of acute leukemia.

In this article, we review the evidence suggesting a possible role for B19 virus in the pathogenesis of a subset of cases of acute leukemia. Human parvovirus B19 infection may complicate the clinical course of patients with acute leukemia and may also precede the development of acute leukemia by up to 180 days. Parvovirus B19 targets erythroblasts in the bone marrow and may cause aplastic crisis in patients with shortened-red cell survival. Aplastic crisis represents a prodrome of acute lymphoblastic leukemia in 2% patients. There is a significant overlap between those HLA classes I and II alleles that are associated with a vigorous immune response and development of symptoms during B19 infection and those HLA alleles that predispose to development of acute leukemia. Acute symptomatic B19 infection is associated with low circulating IL-10 consistent with a vigorous immune response; deficient IL-10 production at birth was recently found to be associated with subsequent development of acute leukemia. Anti-B19 IgG has been associated with a particular profile of methylation of human cancer genes in patients with acute leukemia, suggesting an additional hit and run mechanism. The proposed role for parvovirus B19 in the pathogenesis of acute leukemia fits well with the delayed infection hypothesis and with the two-step mutation model, which describes carriage of the first mutation prior to birth, followed by suppression of hematopoiesis, which allows rapid proliferation of cells harboring the first mutation, acquisition of a second activating mutation, and expansion of cells carrying both mutations, resulting in acute leukemia.

Mucosal immunity induced by orally administered transgenic plants.

Oral immunization is an efficient means to induce protection at the portal entrance for many pathogens. Therefore, the design of efficient edible vaccines through transgenic plants represents a challenging alternative to the traditional injectable ones. We have previously reported the construction of transgenic potato plants expressing the genes coding for the immunogenic proteins of Newcastle Disease Virus (NDV) and their immunogenicity in mice. All mice receiving transgenic plant extracts in incomplete Freund's adjuvant produced specific antibodies. Animals fed with transgenic leaves also showed a specific response against NDV. The aim of the present study was to continue the evaluation of the mucosal immune response. Adult Balb/c mice were fed with potato leaves for a month and on day 36 mucosal samples were collected. ELISAs performed on intestinal washes showed that transformed plants elicited the synthesis of NDV-specific IgG and IgA antibodies. In addition, anti-NDV IgA antibodies were detected in supernatants of cultured small intestine fragments of mice fed with the recombinant immunogens, suggesting the presence of NDV-specific IgA secreting plasma cells in the intestinal tissue. Moreover, we detected specific anti-NDV antibodies in intestinal fluids after oral immunization with F and HN transgenic plants. Also, indirect immunofluorescence on intestinal tissue was performed. The present results suggest that these immunogens, F and HN glycoproteins of NDV, when orally administered, would enhance the number of IgA(+) B cells, and the cytotoxic cellular immune response via CD8(+) T cells, found in the gut lamina propria that is in accordance with our first findings.

Desarrollo de improntas para el diagnostico del virus epstein-barr por inmunofluorescencia indirecta / Development of slides for Epstein-Barr virus diagnosis by indirect immunofluorescence

El vírus de Epstein-Barr (VEB) es el principal agente oncogénico linfotrópico dentro de la família Herpesviridae y se encuentra mundialmente distribuído. La primoinfección se produce en adultos jovenes y se manifesta como mononucleosis infecciosa. La detección de anticuerpos anti-viral cápside antigen (VCA) indica infección previa o presente com VEB. Además, se observan títulos elevados de anticuerpos anti-VCA en las enfermidades neoplásicas asociadas al VEB como los linfomas, em indivíduois HIV-positivos. El objetivo de este estúdio fue el desarrollo y puesta a punto de improntas de células P3HR1 para la detección serológica del VEB por técnicas de inmunofluorescencia indirecta (IFI). Se estimularon cultivos de células P3HR1 en crecimiento exponencial com phorbol-12-mirystoil-13-acetato y se recolectaron alícuotas a distintos tiempos para realizar improntas. Se realizó uma IFI com cada impronta usando como anticuerpo primário um suero VEB-positivo. Se observo un aumento del 11% em la expresión del VCA a las 40 horas post-estimulación, deyendo al 3.5% a las 48 horas. Estos datos fueron corroborados por ensayo de Western blot com inmunodetección. La precisión intra- e inter-lote de las improntas fue evaluada para anticuerpos IgM e IgG, com sueros probados previamente por equipos para esta determinación disponibles en el mercado para el VEB y com sueros reactivos para otros miembros de la família Herpesviridae. No se obtuvieron resultados falsos-negativos ni falsos-positivos para el VEB ni se observo reactividad cruzada com otros herpesvirus. Las improntas desarrolladas constituyen un instrumento para el diagnóstico de la primoinfección del VEB y la detección serológica de anticuerpos IgG anti-VCA de neoplasias asociadas al VEB. (AU)

Desarrollo de improntas para el diagnostico del virus epstein-barr por inmunofluorescencia indirecta / Development of slides for Epstein-Barr virus diagnosis by indirect immunofluorescence

El vírus de Epstein-Barr (VEB) es el principal agente oncogénico linfotrópico dentro de la família Herpesviridae y se encuentra mundialmente distribuído. La primoinfección se produce en adultos jovenes y se manifesta como mononucleosis infecciosa. La detección de anticuerpos anti-viral cápside antigen (VCA) indica infección previa o presente com VEB. Además, se observan títulos elevados de anticuerpos anti-VCA en las enfermidades neoplásicas asociadas al VEB como los linfomas, em indivíduois HIV-positivos. El objetivo de este estúdio fue el desarrollo y puesta a punto de improntas de células P3HR1 para la detección serológica del VEB por técnicas de inmunofluorescencia indirecta (IFI). Se estimularon cultivos de células P3HR1 en crecimiento exponencial com phorbol-12-mirystoil-13-acetato y se recolectaron alícuotas a distintos tiempos para realizar improntas. Se realizó uma IFI com cada impronta usando como anticuerpo primário um suero VEB-positivo. Se observo un aumento del 11% em la expresión del VCA a las 40 horas post-estimulación, deyendo al 3.5% a las 48 horas. Estos datos fueron corroborados por ensayo de Western blot com inmunodetección. La precisión intra- e inter-lote de las improntas fue evaluada para anticuerpos IgM e IgG, com sueros probados previamente por equipos para esta determinación disponibles en el mercado para el VEB y com sueros reactivos para otros miembros de la família Herpesviridae. No se obtuvieron resultados falsos-negativos ni falsos-positivos para el VEB ni se observo reactividad cruzada com otros herpesvirus. Las improntas desarrolladas constituyen un instrumento para el diagnóstico de la primoinfección del VEB y la detección serológica de anticuerpos IgG anti-VCA de neoplasias asociadas al VEB.

Establishment of HTLV-I-infected cell lines from peripheral blood mononuclear cells of Brazilian patients.

To investigate epidemiological and pathogenetic features of HTLV-I infection, a cohort of carriers has been followed at the USP Teaching Hospital since 1991. This study describes the establishment of cell lines from peripheral blood mononuclear cells (PBMC) of infected subjects. Ex vivo PBMC were cultured with those from a seronegative donor and morphologic evidence of cell transformation was obtained after 90 days with detection of multinucleated cells exhibiting cerebriform nuclei. Integration of HTLV-I proviral DNA and expression of viral antigens was demonstrated in culture by PCR and immunofluorescence. Cell lines were maintained for 240 days, gradually weaned from exogenous IL-2. Immunophenotyping of cell lines on flow cytometry yielded evidence of cell activation. Establishment of HTLV-I-infected cell lines from ex vivo PBMC is feasible and may be useful for studies on lymphocyte phenotypic changes and on mechanisms of HTLV-induced cell proliferation. Moreover they may be used with diagnostic purposes in immunofluorescence tests.