Similar Cytokine Responses and Degrees of Anemia in Patients withPlasmodium falciparumandPlasmodium vivaxInfections in the Brazilian Amazon Region

Abstract

The mechanisms of malarial anemia induction are poorly understood, but cytokines and autoantibodies are considered to play important roles. This work aimed at evaluating the degree of anemia and the plasmatic profile of the cytokines tumor necrosis factor alpha (TNF-␣), gamma interferon (IFN-␥), interleukin-12 (IL-12), migration inhibitory factor (MIF), and IL-10 and the monocyte chemotactic protein-1 (MCP-1) chemokine, as well as evaluating the presence of antibodies directed to components of the normal erythrocyte membrane and to cardiolipin in individuals with malaria from the Brazilian Amazon. No difference was observed in the frequency of anemia between patients infected by Plasmodium vivax and those infected by Plasmodium falciparum, and there was no relationship between the levels of parasitemia and the manifestations of anemia in P. vivax and P. falciparum patients. Significant increases in the concentrations of TNF-␣, IFN-␥, MIF, and MCP-1 were observed in patients with P. falciparum and P. vivax malaria, whereas the concentrations of IL-10 was increased only in patients with P. vivax infection. Higher concentrations of IL-12 and IL-10 were observed in the P. falciparum anemic patients, while for TNF-␣ this profile was observed in the nonanemic ones. P. vivax-infected and P. falciparum-infected patients with positive immunoglobulin M (IgM) or IgM and IgG responses, respectively, against blood-stage forms of the parasites had significantly lower hemoglobin levels than did those with negative responses. There was no correlation between the presence of anti-erythrocyte and anti-cardiolipin antibodies and the presence or intensity of the anemia. Our data suggest that in areas of low endemicity and unstable transmission of malaria, P. vivax and P. falciparum infections present similar characteristics in terms of the induction of anemia and cytokine responses.Severe malarial anemia and cerebral malaria are the main complications of Plasmodium falciparum infection. They are responsible for most of the estimated one to three million malaria-related deaths every year in the world, mainly among children below 5 years of age in sub-Saharan Africa (49). Severe malarial anemia is reported to be the earliest complication, usually affecting children below 2 years of age (57). Although severe anemia is a major concern in malaria pathology due to its high mortality rates, milder forms of anemia also are important, since this manifestation is responsible for considerable morbidity and is one of the major factors for the high disability-adjusted life years attributed to malaria (50,51,66). Iron deficiency, intestinal helminths, and human immunodeficiency virus infection make significant contributions to the pathogenesis of anemia in many African countries, but now there is substantial evidence suggesting that malaria is indeed a major underlying factor (28, 48).Although it has been estimated, the real impact of malarial anemia on the affected populations is unknown. The few available data mostly are restricted to studies ...

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