989 resultados para Antigens, CD27 -- immunology


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Paracoccidioidomycosis is a deep endemic mycosis associated with an antigen-specific immunodeficiency. To examine the role of apoptosis in this immunodeficiency, peripheral blood mononuclear cells (PBMC) of patients with paracoccidioidomycosis and controls were stimulated with the main antigen of Paracoccidioides brasiliensis (gp43) and an unrelated fungal antigen (from Candida albicans, CMA) and analyzed for annexin V and propidium iodide staining by flow cytometry. Control PBMC proliferated well with both antigens. Patients' PBMC proliferated only with CMA, but presented higher levels of apoptosis with gp43 and CMA than in their own unstimulated cultures. Moreover, gp43-triggered apoptosis in control PBMC was lower than in those of the patients. Thus, patient but not control gp43-stimulated T cells apparently remained anergized and subsequently underwent apoptosis. While CMA-induced apoptosis is likely triggered by activation-induced cell death, this is apparently not the case in gp43-induced apoptosis because of the lack of cell cycling and IL-2 in the gp43-stimulated cultures. However, higher IL-10 levels were found in gp43-stimulated patient PBMC cultures. Addition of a neutralizing anti-IL-10 antibody to the cultures resulted in increased apoptosis levels only in gp43-stimulated patient PBMC cultures. Our results suggest that apoptosis plays a role in the patients' antigen-specific hyporesponsiveness and that IL-10 may have an antiapoptotic role. (C) 2002 Elsevier B.V. (USA).

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Toxocara vitulorum, a nematode parasite in the small intestine of cattle and water buffaloes, causes high morbidity and mortality of 1-3 months old buffalo calves. This research evaluated the specific perieneteric antigens (Pe) reactivity of anti-T. vitulorum-Pe antibody (Tv-Pe-Ab) in both immune sera and colostrum from buffalo cows immediately post-partum from buffalo cows. The presence of Tv-Pe-Ab in sera of buffalo newborn calves was also examined at 1 day before and after suckling the colostrum as well as in sera from naturally infected calves at the beginning and peak of the maximum infection and then again during the period of rejection and post-rejection of the parasite. Pe antigens were characterized for Tv-Pe-Ab by SDS-PAGE and Western blot (WB). The SDS-PAGE showed that Pe contained nine protein bands (11, 14, 31, 38, 58, 76, 88,112 and 165 kDa). All Pe bands were recognized by Tv-Pe-Ab in sera and colostrum of buffalo cows. Only the serum antibodies of buffalo calves at 1 day of age after suckling the colostrum and during the beginning of T. vitulorum infection recognized Pe antigen's nine bands. In contrast, serum antibodies from 1-day-old buffalo calves, taken before suckling colostrum, did not react with any protein band. In suckling calves, which reached peak egg output, rejection and post-rejection stages of the infection, serum Tv-Pe-Ab reactivity with lower molecular weight protein bands (11-76 kDa) was lost and only reactivity with the Pe protein bands of higher molecular weight (88, 112 and 165 kDa) remained. (c) 2005 Elsevier B.V. All rights reserved.

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Studies have suggested that hepatitis C virus (HCV) may infect not only hepatocytes but may also be carried by platelets. Platelets express more than 20 polymorphic antigenic determinants on their surface, which are called human platelet antigens (HPA), To determine the allele frequency of the HPA-1 to -5 in patients infected with HCV, blood samples were collected from 257 blood donors for the control group and from 191 patients infected with HCV. DNA was isolated and amplified for genes HPA-1 to -4 using PCR Sequence Specific Primers (PCR-SSP) and HPA-5 using PCR-Restriction Fragment Length Polymorphism (PCR-RFLP). The allelic and genotypic frequency of HPA-5a in patients infected with HCV was found to be significantly lower(P < 0.05) than in the controls, and HPA-5b from patients infected with HCV was significantly higher (P < 0.05) than in controls. The increase in HPA5b allelic frequency in HCV infection may indicate a possible association between HCV infection and HPAs. J. Med. Virol. 81:757-759, 2009. (C) 2009 Wiley-Liss, Inc.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The objectives of the present study were to optimize the protocol of mouse immunization with Paracoccidioides brasiliensis antigens (Rifkind's protocol) and to test the modulation effect of cyclophosphamide (Cy) on the delayed hypersensitivity response (DHR) of immunized animals. Experiments were carried out using one to four immunizing doses of either crude particulate P. brasiliensis antigen or yeast-cell antigen, followed by DHR test four or seven days after the last immunizing dose. The data demonstrated that an immunizing dose already elicited response; higher DHR indices were obtained with two or three immunizing doses; there were no differences between DHR indices of animals challenged four or seven days after the last dose. Overall the inoculation of two or three doses of the yeast-cell antigen, which is easier to prepare, and DHR test at day 4 simplify the original Rifkind's immunization protocol and shorten the duration of the experiments. The modulation effect of Cy on DHR was assayed with administration of 2.5, 20 and 100 mg/kg weight at seven day intervals starting from day 4 prior to the first immunizing dose. Only the treatment with 2.5 mg Cy increased the DHR indices. Treatment with 100 mg Cy inhibited the DHR, whereas 20 mg Cy did not affect the DHR indices. Results suggest an immunostimulating effect of low dose of Cy on the DHR of mice immunized with P. brasiliensis antigens.

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