Malaria in
malaria-naïve adults is associated with an inflammatory response characterized by expression of specific activation markers on innate immune cells. Here, we investigate activation and adhesion marker expression, and
cytokine production in monocytes from children presenting with
cerebral malaria (CM, n = 36), severe malarial anaemia (SMA, n = 42) or uncomplicated
malaria (UM, n = 66), and healthy aparasitemic children (n = 52) in Blantyre, Malawi. In all
malaria groups, but particularly in the two severe
malaria groups, monocyte expression of CD11b, CD11c, CD18,
HLA-DR and CD86, and percentages of TNF-α- and IL-6-producing monocytes were lower than in healthy controls, while expression of CD11a, TLR2 and TLR4 was lower in children with severe
malaria compared with controls. These levels mostly normalized during
convalescence, but percentages of
cytokine-producing monocytes remained suppressed in children with SMA. In all
malaria groups, especially the SMA group, a greater proportion of monocytes were loaded with
haemozoin than among controls. In a P. falciparum hyperendemic area, monocytes in children with acute symptomatic
malaria have reduced expression of adhesion molecules and activation markers and reduced inflammatory
cytokine production. This immune suppression could be due to accumulation of
haemozoin and/or previous exposure to P. falciparum.