Leishmanial infection: analysis of its first steps: a review

The first steps in leishmaniasis are critical in determining the evolution of the disease. Major advances have recently been done in understanding this crucial moment. Fundamental research in parasite-vector interaction, parasite biology, insect saliva, and vertebrate host response have shed new light and uncovered a most fascinating and complex moment in leishmaniasis. We review here some of these aspects and we try to connect them in a logical framework.

B-cell infiltration and frequency of cytokine producing cells differ between localized and disseminated human cutaneous leishmaniases

Biopsies from human localized cutaneous lesions (LCL n = 7) or disseminated lesions (DL n = 8) cases were characterized according to cellular infiltration,frequency of cytokine (IFN-g, TNF-alpha) or iNOS enzyme producing cells. LCL, the most usual form of the disease with usually one or two lesions, exhibits extensive tissue damage. DL is a rare form with widespread lesions throughout the body; exhibiting poor parasite containment but less tissue damage. We demonstrated that LCL lesions exhibit higher frequency of B lymphocytes and a higher intensity of IFN-gamma expression. In both forms of the disease CD8+ were found in higher frequency than CD4+ T cells. Frequency of TNF-alpha and iNOS producing cells, as well as the frequency of CD68+ macrophages, did not differ between LCL and DL. Our findings reinforce the link between an efficient control of parasite and tissue damage, implicating higher frequency of IFN-gamma producing cells, as well as its possible counteraction by infiltrated B cells and hence possible humoral immune response in situ

Interleukin 8 as a vaso-occlusive marker in Brazilian patients with sickle cell disease

Sickle cell disease has a worldwide distribution and is a public health problem in Brazil. Although vaso-occlusive crisis (VOC) is one of the most important clinical features of the disease, there are still several steps of its pathogenesis which are unknown. The increase of the chemotactic factor interleukin 8 (IL-8) has been reported to be involved in sickle cell disease crisis, but this has not been demonstrated conclusively. In the present study we analyzed serum IL-8 levels by ELISA and hematological parameters and hemoglobin patterns by standard techniques in 23 (21 SS and 2 SC) Brazilian patients with sickle cell syndromes during VOC caused by different inducing factors, 22 (21 SS and 1 SC) sickle cell patients out of crisis, and 11 healthy controls. Increased IL-8 levels were observed in 19 of 23 VOC patients (79.2 percent), 3 of them with more than 1,000 pg/ml. Seventeen of 22 (77.3 percent) non-crisis patients showed low IL-8 levels (less than 15 pg/ml). Healthy controls had low IL-8 levels. A significant difference in serum IL-8 levels was observed between crisis and non-crisis sickle cell patients (P<0.0001). There was no correlation between IL-8 levels and hematological data or hemoglobin patterns. High serum IL-8 levels were observed in VOC patients independently of the crisis-inducing factor. We conclude that in the studied population, IL-8 concentration may be a useful VOC marker, although the mechanism of the pathogenic process of sickle cell VOC syndromes remains unclear

A dhfr-ts- Leishmania major Knockout Mutant Cross-protects against Leishmania amazonensis

E10-5A3 is a dhfr-ts- Leishmania major double knockout auxotrophic shown previously to induce substantial protection against virulent L. major infection in both genetically susceptible and resistant mice. We investigated the capacity of dhfr-ts- to protect against heterologous infection by L. amazonensis. The degree of protection was evaluated by immunization of BALB/c or C57BL/6 mice with E10-5A3, followed by L. amazonensis challenge. Whether immunized by subcutaneous (SC) or intravenous (IV) inoculation, susceptible and resistant mice displayed a partial degree of protection against challenge with virulent L. amazonensis. SC-immunized BALB/c mice developed lesions 40 to 65 percent smaller than non immunized mice, while IV immunization led to protection ranging from 40 to 75 percent in four out of six experiments compared to non immunized animals. The resistant C57BL/6 mice displayed comparable degrees of protection, 57 percent by SC and 49 percent by IV immunization. Results are encouraging as it has been previously difficult to obtain protection by SC vaccination against Leishmania, the preferred route for human immunization

Human_Leishmaniasis@cytokines.bahia.br

The cell-mediated immune response is critical in the resistance to and recovery from leishmaniasis. Cytokines are central elements in mounting an immune response and have received a great deal of attention in both human and experimental leishmaniasis. IFN-gamma is responsible for macrophage activation leading to leishmanicidal mechanisms. Understanding the balance of cytokines that lead to enhanced production of or synergize with IFN-gamma, and those cytokines that counterbalance its effects is fundamental for developing rational immunotherapeutic or immunoprophylactic approaches to leishmaniasis. Here we focus on the cytokine balance in human leishmaniasis, particularly IL-10 as an IFN-gamma opposing cytokine, and IL-12 as an IFN-gama inducer. The effects of these cytokines were evaluated in terms of several parameters of the human immune response. IL-10 reduced lymphocyte proliferation, IFN-gamma production and cytotoxic activity of responsive human peripheral blood mononuclear cells. Neutralization of IL-10 led to partial restoration of lymphoproliferation, IFN-gamma production and cytotoxic activity in unresponsive visceral leishmaniasis patients. IL-12 also restored the responses of peripheral blood mononuclear cells from visceral leishmaniasis patients. The responses obtained with IL-12 are higher than those obtained with anti-IL-10, even when anti-IL-10 is combined with anti-IL-4.

Transforming growth factor-ß in tegumentary leishmaniasis

1. The course of infection with the protozoan parasite Leishmania is determined in part by its early replication in macrophages, the exclusive host cells for these organisms. Resistance to and recovery from leishmanial infection is related to cell-mediated immune responses in all forms of human and murine leishmaniasis. 2. Factors contributing to the early inhibition or proliferation of Leishmania are poorly understood, but cytokines such as IFNÔ, IL-10 or transforming growth factor ß (TGF-ß) are known to influence the replication of Leishmania in macrophages. 3. TGF-ß is a multipotential cytokine with diverse effects on cells of the immune system, including down-regulation of certain macrophage functions. Infection of murine or human macrophages by Leishmania induces the production of active TGF-ß. Recombinant TGF-ß added to murine or human macrophage cultures leads to increased intracellular replication of Leishmania. Exogenous TGF-ß administered in vivo promotes enhancement of infection, whereas its neutralization by monoclonal antibodies decreases the level of in vitro infection, and protects susceptible mice. 4. Susceptible animals treated with anti-TGF-ß monoclonal antibodies change their immune response, not increasing the expression of IL-4 while increasing the expression of IFNÔ mRNA in their draining lymph nodes. Resistant animals treated with TGF-ß also change their pattern of immune response as indicated by an increase of the important Th2 cytokine IL-10 mRNA in the draining lymph node. 5. TGF-ß has profound effects on the host response to Leishmania in both mouse and man, and probably is an important parasite escape mechanism

Evaluation of the histopathological classifications of American cutaneous and mucocutaneous leishmaniasis

In order to evaluate the reliability of histopathological classifications of cutaneous and mucocutaneous leishmaniasis the authors compared the histopathological patterns of two biopsies taken simultaneously from the same patient, and classified the material according to Ridley et al. (1980), to Magalhäes et al. (1986a), and to a more simplified classification with only three patterns. District histopathological aspects, were observed in different lesions or even in the same lesion. The authors concluded that histopathological patterns do not represent a stage of tegumentary leishmaniasis, thus they can not be correlated with prognosis and therapeutical response as suggested in the literature

Immunological studies with the venom of the scorpion Tityus serrulatus

We describe a "sandwich" enzyme-linkedimmunosorbent assay (ELISA) sensitive to quantities of scorpion (Tityus serrulatus) venom (TsV) in the range of 1-3 ng?ml sample. Cross-reactivity with the venom from the rattlesnake Crotalus durissus terrificus and with venoms from several snakes of the Bothrops genus was detected only at concentrations higher than 1 *g/ml sample. A conventional ELISA is also described for the detection of antibodies against TsV. Analysis by Western Blot (WB) demonstrated a 25-kDa protein band common to TsV and to the venoms of Bothrops moojeni, B. jararacussu and B. jararaca. Venom from C. d. terrificus exhibited WB cross-reactive bands of 16 and 25 kDa with TsV

Serum interferon activity of patients with leishmaniasis

Serum from a significant proportion of 29 cutaneous and 12 mucocutaneous leishmaniasis patients exhibited interferon activity in a cytopathic assay: positive tests were obtained for 24.1% and 41.7% of the patients, respectively. Similar positive frequencies were observed in other parasitic diseases (schistosomiasis, 12.5%; toxoplasmosis, 20%; Chagas' disease, 16%; leprosy, 12.5%; tuberculosis, 30%). In contrast, none of the 44 serum samples from American visceral leishmaniasis (AVL) patients had interferon activity during the active stage of the disease. However, 13% of the samples obtained from patients recovered from AVL were positive

Estudio comparartivo del proceso de purificación de anticuerpos monoclonales mediante cromatografía de adsorción en hidroxiapatita / Comparative study of the purification of monoclonal antibodies using hydroxiapatite absortion chromatography

En el presente trabajo se compara la purificación de anticuerpos monoclonales de ratón de diferentes clases y subclases (IgG1, IgG2 e IgM) por cromatografía de adsorción en hidroxiapatita (BioRad) y en hidroxiapatita-Ultrogel (LKB). Se analizaron los factores capacidad de adsorción, rendimiento, tiempo de corrida (velocidad de flujo), reciclaje y capacidad de enlazamiento específicos de los anticuerpos obtenidos inmediatamente después de la purificación y posterior a su almacenamiento. Se concluye que la cromatografía de adsorción en hidroxiapatita, y en específico, luego de que esta sustancia acoplada a un soporte adecuado (HA Ultrogel), constituye un método fácil, sencillo, rápido y eficiente para la purificación de anticuerpos monoclonales

A simple method for assessing the binding of concanavalin A to mononuclear cell surfaces: no interference of visceral leishmaniasis serum on this binding

Descrevemos um método simples para determinaçäo da ligaçäo da Concanavalina A na superfície de células mononucleares do sangue periférico humano. A ligaçäo é revelada por método imuno-enzimático utilizando imunoglobulina, conjugada à peroxidase, obtida de soro de coelho anti-ConA