Detection of antibodies to variant antigens on Plasmodium falciparum-infected erythrocytes by flow cytometry

TY - JOUR

T1 - Detection of antibodies to variant antigens on Plasmodium falciparum-infected erythrocytes by flow cytometry

AU - Staalsoe, T

AU - Giha, H A

AU - Dodoo, D

AU - Theander, T G

AU - Hviid, L

N1 - Keywords: Adult; Animals; Antibodies, Protozoan; Antigens, Protozoan; Erythrocytes; Flow Cytometry; Humans; Plasmodium falciparum; Rabbits

PY - 1999

Y1 - 1999

N2 - 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.

AB - 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.

U2 - 10.1002/%28SICI%291097-0320%2819990401%2935%3A4%3C329%3A%3AAID-CYTO5%3E3.3.CO%3B2-P

DO - 10.1002/%28SICI%291097-0320%2819990401%2935%3A4%3C329%3A%3AAID-CYTO5%3E3.3.CO%3B2-P

M3 - Journal article

C2 - 10213198

SN - 1552-4949

VL - 35

SP - 329

EP - 336

JO - Cytometry Part B - Clinical Cytometry

JF - Cytometry Part B - Clinical Cytometry

IS - 4

ER -