Detection of antibodies to variant antigens on Plasmodium falciparum‐infected erythrocytes by flow cytometry
T Staalsoe, HA Giha, D Dodoo… - … : The Journal of the …, 1999 - Wiley Online Library
Cytometry: The Journal of the International Society for Analytical …, 1999•Wiley Online Library
Background: Naturally induced antibodies binding to surface antigens of Plasmodium
falciparum–infected erythrocytes can be detected by direct agglutination of infected
erythrocytes or by indirect immunofluorescence on intact, unfixed, infected erythrocytes.
Agglutinating antibodies have previously been shown to recognise Plasmodium falciparum
erythrocyte membrane protein 1 (PfEMP1). This protein is inserted by the parasite into the
host cell membrane and mediates the adhesion to the venular endothelium of the host …
falciparum–infected erythrocytes can be detected by direct agglutination of infected
erythrocytes or by indirect immunofluorescence on intact, unfixed, infected erythrocytes.
Agglutinating antibodies have previously been shown to recognise Plasmodium falciparum
erythrocyte membrane protein 1 (PfEMP1). This protein is inserted by the parasite into the
host cell membrane and mediates the adhesion to the venular endothelium of the host …
Background
Naturally induced antibodies binding to surface antigens of Plasmodium falciparum–infected erythrocytes can be detected by direct agglutination of infected erythrocytes or by indirect immunofluorescence on intact, unfixed, infected erythrocytes. Agglutinating antibodies have previously been shown to recognise Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). This protein is inserted by the parasite into the host cell membrane and mediates the adhesion to the venular endothelium of the host organism in vivo.
Methods
Erythrocytes infected at high parasitaemias with ethidium‐bromide‐labelled mature forms of P. falciparum parasites were sequentially exposed to immune plasma, goat anti‐human immunoglobulin (Ig) G, and fluorescein‐isothiocyanate‐conjugated rabbit anti‐goat Ig. Plasma antibodies recognising antigens exposed on the surface of parasitised erythrocytes were subsequently detected by two‐colour flow cytometry.
Results
Binding of human antibodies to the surface of erythrocytes infected with adhesive strains of Plasmodium falciparum can be measured by the two‐colour flow cytometry (FCM) assay described. In addition, we demonstrate that the adhesive capacity of a parasite isolate correlates with the capacity of human immune plasmas to label the isolate as detected by FCM. We also show that the antigens recognised by the labelling antibodies are strain specific and that their molecular weights are in the range previously described for PfEMP1 antigens.
Conclusions
Our FCM assay predominantly detects antibodies that recognise PfEMP1 and thus constitutes a convenient assay for the analysis of acquisition, maintenance, and diversity of anti‐PfEMP1‐specific antibodies and for the examination of class and subclass characteristics. Cytometry 35:329–336, 1999. © 1999 Wiley‐Liss, Inc.
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