The expression of LFA-1, MAC-1 and ICAM-1 on leucocytes from patients with uncomplicated and those with complicated plasmodium falciparum malaria
Ogonda, Lilian Adhiambo
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Malaria is a major cause of morbidity and mortality in sub-Saharan Africa. Most of the mortality is the result of severe infections that occur in a small proportion of individuals, mostly children and pregnant women. A clear understanding of factors that play a role in the pathogenesis of severe complicated P. falciparum malaria is essential as this will accelerate the development of effective preventive and therapeutic measures. Findings from a number of experimental and clinical studies suggest that the interaction of the parasite, the host leucocytes and the endothelium is critical to the development of severe disease. This interaction takes place through the use of cell surface adhesion receptors such as ICAM-1, LFA-1 and MAC-1 present on the surface of the endothelial cell and leucocyte. However, little is known concerning the relationship between the expression of these adhesion molecules on leucocytes from different individuals and the clinical manifestation of cerebral malaria, severe malarial anaemia, and uncomplicated malaria. The purpose of the present study was to investigate differences in expression pattern of ICAM-1, LFA-1 and MAC-1 on leucocytes from naturally infected non-immune children from a malaria endemic area and correlate these with the disease state. Children with malarial anaemia or cerebral malaria (coma) were compared to controls of the same age and gender who had uncomplicated malaria or were asymptomatic. Using cytofluorometric techniques, the surface ICAM-1, LFA-1, and MAC-1 were quantified during an episode of acute malaria as well as during a subsequent one-month follow-up for all groups. The results from this study have shown that: (i) CD11a expression on monocytes and lymphocytes was lower in cases of acute malaria regardless of clinical status and there were no significant differences in the expression of CD11a between cases of severe anaemia and cerebral malaria. (ii) The percent CD11b positive granulocytes and their level of expression were higher in cases of cerebral malaria than in symptomatic controls, asymptomatic controls and cases of severe anaemia. In addition, the percent CD11b positive monocytes and their level of expression were higher among the cerebral malaria convalescent children than among the symptomatic controls, asymptomatic controls and severe anaemia convalescent children. (iii) The percent CD54 positive cells and their level expression were higher in cases of severe malarial anaemia, cerebral malaria and symptomatic controls (clinically ill patients) than in asymptomatic controls. These findings suggest that differences exists between clinical groups within the CM and SA cohorts in the expression of ICAM-1 and the 2 integrin molecules on leucocytes. These differences may be relevant to the pathogenesis of severe P. falciparum malaria.
- MST-Zoological Sciences