Abstract
BackgroundFulani ethnic group individuals are less susceptible than sympatric Mossi ethnic group, in term of malaria infection severity, and differ in antibody production against malaria antigens. The differences in susceptibility to malaria between Fulani and Mossi ethnic groups are thought to be regulated by different genetic backgrounds and offer the opportunity to compare haematological parameters, Tregs and γδT cell profiles in seasonal and stable malaria transmission settings in Burkina Faso. The study was conducted at two different time points i.e. during the high and low malaria transmission period.ResultsTwo cross-sectional surveys were undertaken in adults above 20 years belonging either to the Fulani or the Mossi ethnic groups 1) at the peak of the malaria transmission season and 2) during the middle of the low malaria transmission season. Full blood counts, proportions of Tregs and γδ T cells were measured at both time-points.As previously shown the Fulani and Mossi ethnic groups showed a consistent difference in P. falciparum infection rates and parasite load. Differential white blood cell counts showed that the absolute lymphocyte counts were higher in the Mossi than in the Fulani ethnic group at both time points. While the proportion of CD4+CD25high was higher in the Fulani ethnic group at the peak of malaria transmission season (p = 0.03), no clear pattern emerged for T regulatory cells expressing FoxP3+ and CD127low. However CD3+γδ+ subpopulations were found to be higher in the Fulani compared to the Mossi ethnic group, and this difference was statistically significant at both time-points (p = 0.004 at low transmission season and p = 0.04 at peak of transmission).ConclusionOur findings on regulatory T cell phenotypes suggest an interesting role for immune regulatory mechanisms in response to malaria. The study also suggests that TCRγδ + cells might contribute to the protection against malaria in the Fulani ethnic group involving their reported parasite inhibitory activities.
Highlights
Fulani ethnic group individuals are less susceptible than sympatric Mossi ethnic group, in term of malaria infection severity, and differ in antibody production against malaria antigens
The differences between the two groups were suggested to be due to a functional deficit in regulatory T cells, as reflected by lower expression of TGFb, TGFbRs, CTLA4, and FOXP3 genes in Fulani compared with Mossi ethnic group or European donors not exposed to malaria [12]
It was reported that cloned gδ cells are cytotoxic for P. falciparum in vitro [16,17,18] and that gδ T cells inhibit in vitro growth of the asexual blood stages of Plasmodium falciparum by a granule exocytosis-dependent cytotoxic pathway that required granulysin [19]. gδT cells can carry out many diverse functions, but individual subsets within the population have more restricted effector properties, depending on their expressed TCRs [20]. gδ T cells have been implicated in the pathogenesis of malaria [21]
Summary
Fulani ethnic group individuals are less susceptible than sympatric Mossi ethnic group, in term of malaria infection severity, and differ in antibody production against malaria antigens. Considering clinical protection against malaria in resident populations of endemic areas, previous studies have shown consistent differences in Plasmodium falciparum infection rates, malaria morbidity, prevalence and levels of antibodies to various P. falciparum antigens between Mossi and Fulani ethnic groups, where the Fulani ethnic group individuals are clearly less parasitized, and less affected by the disease [2,3,8,9,10]. In severe P. falciparum malaria haematologic disorders which are the most common complications, play a major role in these fatal complications These changes involve red blood cells, leukocytes, and haemostasis [25]. Haematological changes were mild in the first 24 hours, but continued to deteriorate for few days after anti-malarial therapy
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