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Expressão dos receptores FC de imunoglobulina A em fagócitos do sangue de pacientes com bacteremia. / Expression of immunoglobulin a FC receptors on blood phagocytes of patients with gram-negative bacteremia.

Expressão aumentada do receptor Fc de IgA (CD89) e da cadeia g associada, avaliadas respectivamente por citometria de fluxo e por “immunobloting", foram encontradas em fagócitos do sangue de pacientes com bacteremia por germes gram-negativos, em comparação com controles e pacientes com bacteremia por gram-positivos. A Mr do CD89 avaliada por SDS-PAGE estava diminuída, com núcleo protéico de 32kDa, sugerindo alteração de glicosilação. O aumento da expressão do CD89 correlacionou-se com aumento dos níveis séricos de IL-6. A cadeia g estava fosforilada nos neutrófilos, sugerindo participação do CD89 na sepsis por gram-negativos. / The expression and function of FcaRI (CD89) were analyzed on blood monocytes and neutrophils of patients with gram-positive and gram-negative bacteremia. Eighteen patients with gram-positive bacteremia, sixteen patients with gram-negative bacteremia and twenty healthy individuals were studied. CD89 expression were analyzed by flow cytometry using specific stained antibodies. Analysis of the surface iodinated CD89 molecules by SDS-PAGE and of the CD89 g-associated chain by immunoblotting also were performed. A marked increase in expression of the a and g subunits of the FcaRI were found on both types of cells in patients with gram-negative bacteremia, but not in patients with gram-positive bacteremia. This increase was independent of serum IgA levels. FcaRI Mr was lower on cells from gram negative patients than on cells from controls (50-65 kDa vs 55-75 kDa) despite of similar 32 kDa backbone, indicating altered glycosylation. Increased levels of FcaRI on blood phagocytes correlated with enhanced serum IL-6 levels, but not with IFN-g or TNF-a levels. The CD89 g-associated chain was phosphorylated on neutrophils, suggesting an engagement of CD89 during gram negative sepsis.

Identiferoai:union.ndltd.org:usp.br/oai:teses.usp.br:tde-14062002-232344
Date21 March 2001
CreatorsChiamolera, Murilo
ContributorsMonteiro Filho, Renato Costa, Velasco, Irineu Tadeu
PublisherBiblioteca Digitais de Teses e Dissertações da USP
Source SetsUniversidade de São Paulo
LanguagePortuguese
Detected LanguageEnglish
TypeTese de Doutorado
Formatapplication/pdf
RightsLiberar o conteúdo para acesso público.

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