The Association of High Prevalence of Trophozoites in Peripheral Blood with Lower Antibody Response to P. falciparum Infected Erythrocytes among Asymptomatic Children in Sudan.

Sara N Mohamed,Ihssan M Osman,Nasreldin H Abdulhadi,Muntasir E Ibrahim,Hiba S Mohamed,Bakri Y Nour,Abdelrahim M El Hussein,Dina A Hassan

doi:10.1155/2016/7987686

Abstract

Background. The most prominent variant surface antigens (VSAs) of Plasmodium falciparum are the var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family, which serves as a parasite-sequestering ligand to endothelial cells. In this study we have examined the antibody reactivity of autologous plasma from symptomatic and asymptomatic malaria infected children against the infected erythrocytes' surface antigens using flow cytometry. Methods. Ethidium-bromide-labelled erythrocytic mature forms of P. falciparum parasites obtained from symptomatic and asymptomatic children were sequentially incubated with autologous plasma and fluorescein isothiocyanate-conjugated (FITC) antihuman IgG. Plasma antibody reactivity was detected by flow cytometry. Results. Asymptomatic children had more prevalence of trophozoites in peripheral blood (66%) compared to symptomatic children (16%), p = 0.002. The mean percentage of infected RBCs reacting with autologous sera was 89.78 among symptomatic children compared to 79.62 among asymptomatic children (p = 0.09). Moreover, the mean fluorescence intensity (MFI) in the asymptomatic was significantly higher compared to symptomatic children (p value = 0.040). Conclusion. Variant surface antigens on Plasmodium falciparum infected RBCs from symptomatic malaria children tend to be better recognized by IgG antibodies. This may suggest a role of some IgG antibodies in severity of malaria.

Highlights

The most prominent variant surface antigens (VSAs) of Plasmodium falciparum are the var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family, which serves as a parasite-sequestering ligand to endothelial cells
There were no significant differences between symptomatic and asymptomatic children in terms of age; the mean starting parasitaemia was significantly higher among symptomatic children (4.59 ± 0.52 parasite/μL) compared to asymptomatic children (1.33 ± 0.52 parasite/μL)
The mean (±SEM) percentage of infected RBCs reacting with autologous sera (VSA-positive cells) was 89.78 ± 1.67 among symptomatic children compared to 79.62 ± 2.97 among asymptomatic children (p = 0.09)

Summary

Introduction

The most prominent variant surface antigens (VSAs) of Plasmodium falciparum are the var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family, which serves as a parasite-sequestering ligand to endothelial cells. In this study we have examined the antibody reactivity of autologous plasma from symptomatic and asymptomatic malaria infected children against the infected erythrocytes’ surface antigens using flow cytometry. Variant surface antigens on Plasmodium falciparum infected RBCs from symptomatic malaria children tend to be better recognized by IgG antibodies. This may suggest a role of some IgG antibodies in severity of malaria. Through interaction with host molecules such as ICAM1, CD36, CR1, and CD31, VSAs play a central role in mediating cytoadherence of infected erythrocytes to host cells This is believed to be responsible for the severe pathology associated with P. falciparum malaria [1]. The predominance of IgG1 and IgG3 cytophilic antibodies in endemic areas has been associated

Methods

Results

Conclusion