Potential association of blood monocyte phenotypes and pathology in plasmodium vivax infection

Abstract

Monocyte subpopulations display distinct phenotypes and functions which can drastically change during inflammatory states. Recently, the increased number of a pro-inflammatory monocytes subpopulation (CD14loCD16hi) during P. falciparum infection was observed, with remarkable levels of CX3CR1, HLA-DR, TREM-1 and CD56 presented in this monocyte subset. However, the role of human blood monocytes in vivax malaria has never been explored. This study aimed to determine any potential association between blood monocyte phenotypes and clinical manifestation in patients with P. vivax infection. Monocyte phenotypes were characterized by immunophenotyping, followed by FACSCalibur, the 4 colors detected cytometer. The investigation was performed as a blind study. The result showed that on admission (D0), both percentage and absolute number of blood monocytes in patients with P. vivax infection are significantly increased (p= 0.0033 and p=0.0073, respectively). Interestingly, the numbers of CX3CR1+CD14loCD16hi blood monocytes are different among the 3 groups of thrombocytopenic patients with severe, moderate and mild thrombocytopenia, which is associated with blood platelet levels. In addition, a positive correlation between CX3CR1+CD14loCD16hi blood monocytes and percentage of hematocrit was observed (r=0.3168, p=0.0436). The results suggested that CX3CR1+CD14loCD16hi blood monocytes are induced during P. vivax infection, which may associate with pathology of the disease.