In populations exposed to Leishmania braziliensis, certain subjects develop skin ulcers, whereas others are naturally protected against cutaneous leishmaniasis. We have evaluated which cytokines are most crucial in the development of skin lesions. We found that active lesions occur in subjects with polarized Th2 or mixed Th1/Th2 responses, both associated with elevated IL-10 production. IL-10 was strongly associated (p = 0.004, odd ratio (OR) = 6.8, confidence interval = 1.9–25) with lesions, excluding IFN-γ, IL-12, TNF, IL-13, and IL-4 from the regression model. IL-10 was produced by blood monocytes and CD4+CD25+ T lymphocytes (mostly Foxp3+). However, we did not observe any difference between the number of these cells present in the blood of subjects with active lesions and those present in resistant subjects. Genetic analysis of the IL10−819C/T polymorphism, located in the IL10 promoter, showed that the C allele increased the risk of lesions (OR = 2.5 (1.12–5.7), p = 0.003). Functional analysis of these variants showed allele-specific binding of nuclear factors. The IL10-819C/C genotype was associated with higher levels of IL-10 than C/T and T/T genotypes. These observations demonstrate an important role for IL-10 in skin lesions in humans infected with L. braziliensis, and identify circulating monocytes and Tregs as principal sources of IL-10 in these patients.

Mixed inflammatory/regulatory cytokine profile marked by simultaneous raise of interferon-g and interleukin-10 and low frequency of tumour necrosis factor-a + monocytes are hallmarks of active human visceral Leishmaniasis due to Leishmania chagasi infection

The role of cytokines on the in vitro proliferative response of peripheral blood mononuclear cells (PBMC) from Schistosoma mansoni infected patients to soluble egg (SEA) and adult worm antigens (SWAP) were evaluated. The results obtained demonstrated that the proliferative response of PBMC from chronic intestinal (INT) patients to SEA and SWAP is increased by the blockage of IL-10 with specific monoclonal antibodies (MAb). The effects of these antibodies were readily reversed by the addition of recombinant IL-10. In contrast, no effect was observed on the PBMC response of acute and hepatosplenic patients (HS) in the presence of anti-IL-10. Anti-IL-4 antibodies decreased the PBMC response of the intestinal (INT) and HS individuals to SEA and SWAP, and the PBMC response of acute patients to SEA but not to SWAP. Addition of anti-IL-5 MAb did not decrease the PBMC response of acute patients to SEA or SWAP. These results suggested that IL-10 has an important role in the modulation of the immune response in chronic asymptomatic patients and that this cytokine may be an important factor in controlling morbidity.

We investigated the cytokine profile of cells of the innate immune response and its association with active

No abstract

A study of Lutzomyia longipalpis (Lutz and Neiva, 1912) (Diptera: Psychodidae), the primary vector of American visceral leishmaniasis (AVL), and the canine form of the disease, was carried out in Porteirinha. The city is situated in the northern part of the Brazilian State of Minas Gerais and is an endemic area of AVL. Systematic phlebotomine captures were performed in seven districts with previously reported cases of canine visceral leishmaniasis, during 2 years (January 2000--December 2001). A total of 2328 specimens of L. longipalpis were captured. The association between the local climate variables and the population density of L. longipalpis was evaluated and rainfall was determined to be a major factor, with increased populations during the rainy season (October--March). At the same time period, blood samples from every dog domiciled in the same seven districts, in total 14,077 animals, were analyzed for infection by viscerotropic Leishmania using indirect immunofluorescence assay (IFA). Accumulated incidence rates of canine VL per district varied from 3.40 to 14.34 for the 2-year period. A positive correlation between the population density of L. longipalpis and the canine cases of visceral leishmaniasis in Porteirinha was observed.

Epidemiological studies were conducted on malaria in three rural areas of the Amazon basin in the State of Rondônia: the town of Costa Marques, Forte Principe da Beira (Fort), and an immigrant settlement in the nearby forest. These studies were instituted to document the malaria problem and to describe the role of immigration on its distribution and prevalence. Hospital records in the town show that the number of malaria cases increased five fold from 1983 to 1987 and that the predominant malaria parasite changed from Plasmodium vivax to P. falciparum. Increased malaria followed increased immigration and colonization of the forest. A series of epidemiologic studies suggested the linkage between malaria and immigration as the prevalence of malaria was 1-2% at the Fort, a stable community, 8-9% at Costa Marques, a growing community, and 14-26% in the new settlements in the forest.

The aim of this study was to examine three distinct groups of schistosomiasis patients and to determine whether cell phenotype profiles could be correlated with the different clinical forms of the disease. The data obtained indicate that Schistosoma mansoni infected patients have a lower percentage of CD3+ T cells than do non‐infected individuals. Interestingly, infected patients presented more than twice the mean percentage of circulating activated T cells (CD3+HLA‐DR+) when compared to the control group. Examination of T lymphocyte subpopulations showed that patients with the severe hepatosplenic form (HS) of the disease had lower levels of both CD8High+ and CD8Low+ cells when compared to the other groups of patients. All infected individuals had a higher percentage of circulating B cells, with an increase in the CD5+ B cell population that was more evident in the HS group. The data presented here are evidence to support a relationship between the hepatosplenic form of the disease, a decrease on the CD8+ cell population and an elevation on CD5+B cells.