A pair of naturally occurring antibodies may dampen complement-dependent phagocytosis of red cells with a positive antiglobulin test in healthy blood donors
A pair of naturally occurring antibodies may dampen complement-dependent phagocytosis of red cells with a positive antiglobulin test in healthy blood donors
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DOI：
10.1111/j.1423-0410.2009.001214.x
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发表时间：
2009-01-01
期刊：
影响因子：
2.7
通讯作者：
Lutz, H. U.
中科院分区：
文献类型：
--
作者：
Alaia, V.;Frey, B. M.;Lutz, H. U.
Background and ObjectiveIt is known that red blood cells (RBC) from healthy blood donors with a positive direct antiglobulin test (DAT) for IgG continue to circulate despite carrying elevated numbers of IgG molecules. To unravel the properties of these RBC-bound IgG, we studied them not only on whole RBC populations, but also on density-fractionated RBCs.Materials and MethodsThe properties of acid-eluted RBC-bound IgG and plasma IgG were studied by ELISA for binding to RBC proteins and opsonins, and by blotting. In vitro phagocytosis was studied on density-separated RBCs.ResultsIgG-DAT-positive blood donors carried most IgG molecules on dense RBCs and had more RBCs of high density than DAT-negative controls. Their densest RBCs were older than the oldest RBCs of DAT-negative controls, based on the band 4 center dot 1a/b ratio. In vitro phagocytosis of senescent RBCs from IgG-DAT-positive donors was 1 center dot 5 to 2 fold higher than that of senescent control cells, but the same or less in the presence of physiological IgG concentrations, implying that RBC-bound IgGs impaired complement-dependent uptake. The IgG molecules on these DAT-positive RBCs comprised anti-band 3 naturally occurring antibodies (NAbs) and were two- to fivefold enriched in anti-C3 and framework-specific anti-idiotypic NAbs as compared to controls. Correspondingly, anti-C3 and framework-specific anti-idiotypic NAbs were proportionally elevated in the plasma of two-thirds of DAT+ donors.ConclusionsExtra-binding of anti-C3 together with anti-idiotypic NAbs to senescent RBC-associated C3 fragments may suppress complement-dependent RBC phagocytosis and may prolong the in vivo life span of RBCs.
