Gradual Decline in Malaria-Specific Memory T Cell Responses Leads to Failure to Maintain Long-Term Protective Immunity to Plasmodium chabaudi AS Despite Persistence of B Cell Memory and Circulating Antibody

The mechanisms responsible for the generation and maintenance of immunological memory to Plasmodium are poorly understood and the reasons why protective immunity in humans is so difficult to achieve and rapidly lost remain a matter for debate. A possible explanation for the difficulty in building up an efficient immune response against this parasite is the massive T cell apoptosis resulting from exposure to high-dose parasite Ag. To determine the immunological mechanisms required for long-term protection against P. chabaudi malaria and the consequences of high and low acute phase parasite loads for acquisition of protective immunity, we performed a detailed analysis of T and B cell compartments over a period of 200 days following untreated and drug-treated infections in female C57BL/6 mice. By comparing several immunological parameters with the capacity to control a secondary parasite challenge, we concluded that loss of full protective immunity is not determined by acute phase parasite load nor by serum levels of specific IgG2a and IgG1. Abs, but appears to be a consequence of the progressive decline in memory T cell response to parasites, which occurs similarly in untreated and drug-treated mice with time after infection. Furthermore, by analyzing adoptive transfer experiments, we confirmed the major role of CD4(+) T cells for guaranteeing long-term full protection against P. chabaudi malaria. The Journal of Immunology, 2008, 181: 8344-8355.

Genotoxicity of cigarette smoking in maternal and newborn lymphocytes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

DNA damage in lymphocytes and buccal mucosa cells of children with malignant tumours undergoing chemotherapy

The aim of the present study was to evaluate DNA damage (micronucleus) in cytokinesis-blocked lymphocytes and exfoliated buccal mucosa cells from children with malignant tumours and under chemotherapy. Micronucleated cells (MNCs) were assessed from children before and during chemotherapy. A total of 21 healthy children (controls), matched for gender and age, were used as control. The results pointed out higher frequencies of micronucleated lymphocytes in children with malignant tumour before any therapy when compared to healthy probands. Furthermore an increase of micronucleated lymphocytes during chemotherapy was detected when compared to the data obtained before chemotherapy. No statistically significant increases of MNCs were noticed in buccal mucosa cells at any of the timepoints evaluated. Taken together, these data indicate that the presence of malignant tumours may increase the frequency of DNA damage in circulating lymphocytes, these cells being more sensitive for detecting chromosome aberrations caused by anti-cancer drugs.

Protective effects of beta-glucan extracted from Agaricus brasiliensis against chemically induced DNA damage in human lymphocytes

beta-Glucans (BGs) are polysaccharides that are found in the cell walls of organisms such as bacteria, fungi, and some cereals. The objective of the present study was to investigate the genotoxic and antigenotoxic effects of BG extracted from the mushroom Agaricus brasiliensis (=Agaricus blazei Murrill ss. Heinemann). The mutagenic activity of BG was tested in single-cell gel electrophoresis assays with human peripheral lymphocytes. In addition, the protective effects against the cooked food mutagen 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) and (+/-)-anti-B[a]P-7,8-dihydrodiol-9,10-epoxide (BPDE), which is the main metabolite of B[a]P, and against ROS (H2O2)-induced DNA damage, were studied. The results showed that the compound itself was devoid of mutagenic activity, and that a significant dose-dependent protective effect against damage induced by hydrogen peroxide and Trp-P-2 occurred in the dose range 20-80 mu g/ml. To investigate the prevention of Trp-P-2-induced DNA damage, a binding assay was carried out to determine whether BG inactivates the amine via direct binding. Since no such interactions were observed, it is likely that BG interacts with enzymes involved in the metabolism of the amine.

Apoptosis in T lymphocytes from spleen tissue and peripheral blood of L. (L.) chagasi naturally infected dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genetic damage in human peripheral lymphocytes exposed to antimicrobial endodontic agents

Objective. Formocresol, paramonochlorophenol, or calcium hydroxide have been widely used in dental practice to eradicate bacteria and consequently to produce root canal disinfection. Taking into consideration strong evidence for a relationship between DNA damage and carcinogenesis, the purpose of the present study was to evaluate the genotoxic effects of antimicrobial endodontic compounds in human peripheral lymphocytes by single-cell gel ( comet) assay. This technique detects DNA strand breaks in individual cells.Study design. A total of 10 mu L of the tested substance solution (formocreso1, paramonochlorofeno1, and calcium hydroxide at 100-mu g/mL concentration) was added to human peripheral lymphocytes from 10 volunteers for 1 hour at 37 degrees C. The negative control group was treated with vehicle control (PBS) for 1 hour at 37 degrees C, as well. For the positive control group, lymphocytes were exposed to hydrogen peroxide at 100 mu M during 5 minutes on ice.Results. No DNA breakage was detected after a treatment of peripheral lymphocytes by formocresol, paramonochlorophenol, or calcium hydroxide at 100 mu g/mL.Conclusions. In summary, our results indicate that exposure to formocresol, paramonochlorophenol, or calcium hydroxide may not be a factor that increases the level of DNA lesions in human peripheral lymphocytes as detected by single-cell gel (comet) assay.

Papel das proteínas Yops de Yersinia pseudotuberculosis na ativação dos linfócitos B

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo soroepidemiológico da co-infecção pelo Vírus da hepatite B em portadores do HIV-1 e/ou com SIDA/AIDS no Estado do Amapá

Fatores de risco e formas de transmissão do Vírus da Imunodeficiência humana (HIV) e o Vírus da hepatite B (VHB) são freqüentemente os mesmos, o qual explica a alta freqüência de co-infecção envolvendo esses dois agentes. O objetivo desta pesquisa foi estimar a prevalência da infecção pelo VHB, analisar possíveis fatores de risco bem como examinar a associação entre a contagem de linfócitos T CD4⁺, CD8⁺ e carga viral plasmática em 129 portadores do HIV. Cada participante foi submetido a um questionário específico e tinha uma amostra de sangue testada para os marcadores sorológicos HBsAg, anti-HBc total, anti-HBs, contagem de linfócitos T CD4⁺, CD8⁺ e carga viral plasmática. A prevalência total de marcadores para o VHB foi de 46,5%, com 3,1% de soropositividade para o HBsAg, 27,1% para o anti-HBc total e 36,4% para o anti-HBs. Após ajuste por regressão logística, os marcadores sorológicos para hepatite B foram associados com as seguintes variáveis: sexo, preferência sexual e escolaridade. A freqüência de marcadores para hepatite B foi de 39,1% em homens e 16,6% em mulheres. A prevalência de marcadores para hepatite B foi 14,4% em homo/bissexuais e 15,4% em heterossexuais. A menor freqüência de hepatite B (1%) foi encontrada em pessoas com nível superior de escolaridade. Não foram observadas diferenças estatisticamente significante entre contagem de linfócitos CD4⁺, CD8⁺ e carga viral plasmática em pacientes co-infectados com VHB comparados com aqueles pacientes infectados somente com HIV.

Immune response of broiler chickens immunized orally with the recombinant proteins flagellin and the subunit B of cholera toxin associated with Lactobacillus spp.

Processo FAPESP: 09/53570-3

Association among XRCC1, XRCC3, and BLHX gene polymorphisms and chromosome instability in lymphocytes from patients with endometriosis and ovarian cancer

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genotoxic and mutagenic effects of erythrosine B, a xanthene food dye, on HepG2 cells

Erythrosine (ErB) is a xanthene and an US Food and Drug Administration approved dye used in foods, drugs and cosmetics. Although its utilization is permitted, ErB is described as inhibitor of enzymes and protein-protein interactions and is toxic to pituitary and spermatogenesis processes. However, the genotoxicity and mutagenicity of ErB is inconclusive in the literature. This study aimed to analyze the genotoxicity of this dye using the alkaline comet assay and is the first investigation to evaluate ErB mutagenicity using the cytokinesis block micronucleus cytome (CBMN-Cyt) assay in HepG2 cells. These cells were chosen because they produce phase I and phase II enzymes that can mimic in vivo metabolism. The cells were treated with seven concentrations (0.1-70.0 mu g mL(-1)) of ErB, and the results showed genotoxicity at the two highest concentrations and mutagenicity at six concentrations. Furthermore, as micronuclei result from clastogenic and aneugenic processes, while comet assay is often considered more sensitive and detects DNA single strain breaks, we suggest that an aneugenic is responsible for the observed damage. Although ErB is approved for use in the food, cosmetic and pharmaceutical industries, it must be used carefully because it damages the DNA structure. (C) 2012 Elsevier Ltd. All rights reserved.