Footpad infection of C3HeB/FeJ mice with Leishmania amazonensis leads to chronic lesions accompanied by large parasite loads. Co-infecting these animals with L. major leads to induction of an effective Th1 immune response that can resolve these lesions. This cross-protection can be recapitulated in vitro by using immune cells from L. major-infected animals to effectively activate L. amazonensis...

The use of infectious pathogens has allowed the detection of the development of synergism between pathogens and ubiquitous environmental chemical contaminants. This synergism has been demonstrated to result in a state of immunosuppression which either did not occur in the independent and singular presence of the chemical or pathogen and/or was greater than additive when both were combined. The ...

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi CHAPTER 1. General introduction . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Thesis organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 The immune response to intracellular pathogen . . . . . . . . . . . . . . . . . . 2 1.2.1 Innate immunity . . . . . . . . . . . . . . . . ...

Cutaneous leishmaniasis (CL) is the most common clinical form of American tegumentary leishmaniasis caused by Leishmania (Viannia) braziliensis. CL is associated with a strong Th1 immune response. This exacerbated inflammatory response is correlated with severity of disease and delays the healing time of the ulcer. The fourth-generation immucillin derivative (DI4G), a potent inhibitor of purine...

In tegumentary leishmaniasis caused by Leishmania braziliensis, there is evidence that increased production of IFN-γ, TNF-α and absence of IL-10 is associated with strong inflammatory reaction and with tissue destruction and development of the lesions observed in cutaneous leishmaniasis (CL) and mucosal leishmaniasis (ML). We evaluate the role of regulatory cytokines and cytokine antagonists in...

In Brazil, the percentage of infected dogs living in areas where canine visceral leishmaniasis (CVL) is endemic ranges from 10 to 62%; however, the prevalence of infection in dogs is probably higher than figures reported from serological studies. In addition, problems with the occurrence of false-positive or false-negative results in the serodiagnosis of CVL have been reported. The present work...

Leishmania major induces the rapid production of interleukin-4 (IL-4) in both susceptible BALB/c and resistant B10.D2 mice. In both strains, IL-4 is produced by T cells which react to the parasite LACK (for Leishmania homolog of the receptor for activated C kinase) antigen. The rapid production of IL-4 in B10.D2 mice does not confer susceptibility but results in increased parasite burdens.

T cell-mediated immunity is critical in resistance against Leishmania parasites, and T cell activation requires signals provided by costimulatory molecules. Herein we evaluated the role of costimulatory molecules on cytokine production and T cell surface molecule expression by peripheral blood mononuclear cells (PBMC) from cutaneous leishmaniasis (CL) patients. PBMC from CL patients were stimul...

Despite several drawbacks, rK39-based rapid immunochromatographic test is widely used for the diagnosis of visceral leishmaniasis (VL) in the Indian subcontinent. There is an urgent need to develop a better antigen. In this study we separated crude soluble antigens of Leishmania donovani by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and hybridized with pool sera from pre- and pos...

Vi antibody response of rabbits varied depending on whether Vi antigen was administered in particulate or soluble state. Vi antigen in particulate form induced hemagglutinins, bacterial agglutinins, and passive cutaneous anaphylaxis (PCA) antibodies, whereas soluble Vi antigen induced only hemagglutinins. Guinea pigs passively sensitized with antisera against particulate Vi antigen gave PCA rea...