High IFN-gamma and TNF production by peripheral NK cells of Colombian patients with different clinical presentation of Plasmodium falciparum

Seventeen patients with acute and three with severe P. falciparum malaria patients from the Northwest region of the country were recruited in the study. In addition, 20 healthy controls were included: 10 from Medellin (no-transmission area) and 10 from the Uraba region (a malaria endemic area). Immunophenotypic analysis of peripheral mononuclear cells was performed by FACS to detect total number of NK cells, subtypes and intracellular IFNγ and TNF production by NK cells in the different patient groups.The total mean CD56+/CD3- NK cell proportions in acute and severe malaria subjects were 9.14% (7.15%CD56dim, 2.01%CD56bright) and 19.62% (16.05%CD56dim, 3.58%CD56bright), respectively, in contrast to healthy controls from endemic (total mean CD56+/CD3-1.2%) and non-endemic area (total mean CD56+/CD3- 0.67%). Analysis of basal IFNγ and TNF levels confirmed the CD56bright NK population as the main cytokine producer (p < 0.0001) in the groups affected with malaria, with the CD56dim NK cell exhibiting the highest potential of TNF production after stimulus in the acute malaria group.The results confirm the important role of not only CD56bright but also of CD56dim NK cell populations as producers of the two cytokines in malaria patients in Colombia.The clinical presentation of malaria depends on the confluence of diverse factors, including the degree of natural and acquired specific immunity, host's genetic composition, age, occupation and social and economic factors of the population [1].Malaria in Colombia is highly endemic in the north-west, Pacific Coast and Amazon regions, all among the most deprived of the country due to social-political conflicts resulting in migrations and poverty. Previous studies in the northwest of Colombia, confirmed that children below 12 years of age are highly susceptible to malaria with a mean seven years of age for clinical presentation with malaria [2]. About 70% of this young population was affected by chronic malnutrition and 85% with int