Surface membrane expression by human blood leukocytes and platelets of decay-accelerating factor, a regulatory protein of the complement system

Abstract

The decay-accelerating factor (DAF), an integral membrane protein of approximately 75,000 mol wt that regulates the stability of the C3 convertases of the classical and alternative complement pathways, was initially isolated from normal erythrocyte stroma and used to prepare a polyclonal antiserum. Previously, anti-DAF antiserum has been used to immunoprecipitate DAF from surface-labeled normal erythrocytes and to document the deficiency of DAF on the surface of erythrocytes from patients with paroxysmal nocturnal hemoglobinuria, a condition in which erythrocytes express abnormal sensitivity to complement-mediated lysis. DAF has now been demonstrated by cytofluorography with anti-DAF F(ab')2 and fluoresceinated second antibody to be present on the surface of resting polymorphonuclear leukocytes (PMN), monocytes, lymphocytes, and platelets. Populations of PMN, monocytes, and platelets each exhibited a unimodal distribution of fluorescent staining, reflecting uniform cellular expression of DAF antigen, while the lymphocyte population had a skewed pattern of staining, indicating the heterogeneous expression of DAF antigen. For platelets, the shift in mean fluorescence channel observed with cytofluorographic analysis was minimal, but the presence of surface DAF on platelets was demonstrated by specific and saturable anti-DAF F(ab')2 binding. The DAF antigen, analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of dithiothreitol- reduced anti-DAF immunoprecipitates prepared from surface-labeled, isolated populations of cells, presented a single polypeptide chain of approximately 84,000 mol wt for PMN and 75,000 to 80,000 mol wt for monocytes, T and B lymphocytes, and platelets. Thus, the complement regulatory protein, DAF, is expressed on the surface of all major types of circulating blood cells from normal donors.

Nonlethal adherence to human neutrophils mediated by Dr antigen-specific adhesins of Escherichia coli

“…5), suggest that the receptor on PMNs for the Dr hemagglutinin (and, by extension, the rest of the Dr family) is biochemically similar to the receptor for these adhesins on erythrocytes. This conclusion is consistent with the hypothesis that DAF, which is present on PMNs (31,32) and is the Dr adhesin receptor on erythrocytes (39) and in human tissues (19), is the Dr adhesin receptor on PMNs. In particular, the short consensus repeat 3 (SCR3) domain of DAF has been shown to be the binding site for the entire Dr family of adhesins (34).…”

“…The presence of such receptors on renal tubular basement membranes, Bowman's capsule, and transitional epithelium has been proposed to underlie the importance of Dr adhesin-positive E. coli in ascending colonization of the urinary tract (21,34,39). The Dr adhesin receptor DAF is also present on the surfaces of PMNs (31,32). However, it is not known whether receptor epitopes for Dr family adhesins are conserved on the molecular form of DAF present on PMNs and whether the number, distribution, and accessibility of DAF molecules on PMNs is sufficient to support adherence by Dr adhesin-positive bacteria.…”

Platelets interact with Coxsackieviruses B and have a critical role in the pathogenesis of virus‐induced myocarditis

“…Of note, the presence of CAR on the platelet surface is still controversial, because it has been shown to be absent , present in all platelets or restricted to a sub‐fraction (3%) of the platelets . Although some CVB interact with the decay‐accelerating factor (DAF) , which is a complement regulatory protein that is expressed commonly on most cell surfaces, including human platelets , our previous studies showing that the CVB3 variant used was not blocked by soluble recombinant human DAF or by blocking antisera, as reported by others , strongly suggest that DAF was not involved. Although we observed a moderate reduction when platelet glycoproteins (GP) α IIb β 3 integrin and GPIb were blocked, the reported association of platelets with many different viruses such as Herpes, Vaccinia, Hanta, Echo, HIV or DENV, points out that platelets can bind viruses in a receptor‐independent way, as has been proven for HCV .…”

Platelet Activation in Hemolytic Uremic Syndrome

“…In addition, in a mouse model of chronic serum sickness, platelet-associated factor H was shown to process immune complexes and limit their accumulation in glomeruli. 138 In addition to inhibition in the fluid phase, platelets possess decay-accelerating factor, 46,139 (Table 1) as well as CD46 and CD59. Patients with paroxysmal nocturnal hemoglobinuria lack membrane-bound complement regulators on platelets 140 due to a mutation in the PIG-A gene and aborted synthesis of glycosylphosphoinositol anchors on the surface of erythrocytes, leukocytes, and platelets.…”