Chiamolera M, Launay P, Montenegro V, Rivero M C, Velasco I T, Monteiro R C
Divisions of Emergency Medicine, University of São Paulo, São Paulo, Brazil.
Shock. 2001 Nov;16(5):344-8. doi: 10.1097/00024382-200116050-00004.
Sepsis caused by gram-negative bacteria is a common finding having high incidence and mortality. Fc alpha RI (CD89), a receptor for immunoglobulin A (IgA), has been shown to mediate bacterial phagocytosis, which might play a role in the pathogenesis of sepsis. In this study the expression and function of Fc alpha RI were analyzed on blood monocytes and neutrophils of patients with bacteremia. We found a marked increased in expression of the alpha- and gamma-subunits of the Fc alpha RI 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. Fc alpha RI M(r) was lower on cells from gram-negative patients than on cells from controls (50-65 kDa versus 55-75 kDa), despite a similar 32-kDa backbone, indicating altered glycosylation. Increased levels of Fc alpha RI on blood phagocytes correlated with enhanced serum IL-6 levels, but not with IFN gamma or TNF-alpha. FcR-gamma chain associated with Fc alpha RI was phosphorylated in patients neutrophils, indicating functional engagement of this receptor during gram-negative sepsis. Increased expression and activation of Fc alpha RI-gamma 2 complexes following gram-negative infections suggests its involvement in host defense against bacteria.
革兰氏阴性菌引起的败血症很常见，发病率和死亡率都很高。免疫球蛋白A（IgA）的受体FcαRI（CD89）已被证明可介导细菌吞噬作用，这可能在败血症的发病机制中起作用。在本研究中，分析了菌血症患者血液单核细胞和中性粒细胞上FcαRI的表达和功能。我们发现革兰氏阴性菌血症患者的这两种细胞上FcαRI的α和γ亚基表达均显著增加，而革兰氏阳性菌血症患者则未出现这种情况。这种增加与血清IgA水平无关。尽管有相似的32 kDa主链，但革兰氏阴性菌血症患者细胞上的FcαRI M(r)低于对照组细胞（50 - 65 kDa对55 - 75 kDa），表明糖基化改变。血液吞噬细胞上FcαRI水平的升高与血清IL - 6水平升高相关，但与IFNγ或TNF - α无关。革兰氏阴性菌血症患者中性粒细胞中与FcαRI相关的FcR - γ链发生磷酸化，表明在革兰氏阴性菌败血症期间该受体发挥了功能作用。革兰氏阴性菌感染后FcαRI - γ2复合物表达和激活的增加表明其参与了宿主对细菌的防御。
