B cell dependent T lymphocyte responses in leishmaniasis

The activation of B cell dependent T cells during Leishmania infection cannot be considered a trivial event, because their removal profoundly alters the course and outcome of infection within genetically susceptible and resistant mouse strains. The demonstration that idiotype recognizing T cells also appear within human populations sensitized to leishmanial antigens as a result of asymptomatic or subclinical infections supports a role for these cells in immunity. These cells are not demonstrable in patients with active visceral disease, so that their role in promoting specific unresponsiveness has not been extended to humans. Whether B cell dependent, idiotype specific T cells represent a functionally distinct T lymphocyte subset with unique regulatory activities remains to be determined.

Zoonotic cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis associated with domestic animals in Venezuela and Brazil

After outbreaks of cutaneous leishmaniasis in Solano State, Venezuela, 5% of the population had parasitized ulcers while after similar outbreaks in Mesquita, Rio de Janeiro State, Brazil, 9% had the disease. In these foci children, including some under six years of age, wre affected. There was no significant difference in the occurence of the disease according to sex or type of employment. In Solano, 3% of dogs and 28% of donkeys had parasitized lesions, while in Mesquita these indices were 19.8% and 30.8% respectively. The parasite from man, dogs and equines was identified as Leishmania (Viannia) braziliensis, by zymodeme and serodeme characterization. In these foci there is evidence suggesting that leishmaniasis is a zoonosis, possibly with equine and dogs as reservoirs, although both a wild enzootic cycle and the role of man as a source of infection can not be ruled out. Transmission is assumed to occur peridomestically by sandfly vectors such as Lutzomyia panamensis in Venezuela and Lutzomyia intermedia in Brazil. Information about the origin of these foci suggests that infected equines may be an important factor in the dissemination of the parasite in a peridomestic situation where these sandflies are abundant.

Xenodiagnostico con Lutzomyia youngi en casos venezolanos de leishmaniasis cutaned por Leishmania braziliensis

Xenodiagnósticos con Lutzomya yungi aplicados en los bordes de las úlceras de pacientes infectados con Leishmania braziliensis antes y después del tratamiento con 10 dosis de antimonial pentavalente y un aminoglicósido, evidencian la condición reservoria de leishmanias del enfermo, para flebótomos endofágicos y la utilidad de un tratamiento específico-temprano que no solamente conduce a la curación clínica, sino a la eliminación del riesgo de una eventual transmisión intradomiciliar por insectos que pican dentro del domicilio durante la noche.

Deteccion de amastigotas en Leishmaniasis cutanea y mucocutanea por el metodo de inmunoperoxidasa, usando anticuerpo policlonal: sensibilidad y especificidad comparadas con metodos convencionales de diagnostico

Con el objeto de aumentar la sensibilidad del diagnóstico histopatológico de lesiones cutáneas y mucocutáneas causada por subespecies del complejo Leismania braziliensis y para lograr una mejor visualización de los parásitos en las lesiones, se evaluó el método de la inmunoperoxidas indirecta para localizar en forma rápida y específica los amastigotas en biopsia de tejido afectado. Los cortes de tejido se fijaron en formol y se incluyeron en parafina; después se evaluaron por inmunohistoquímica usando un antisuero policlonal producido en conejo, como reactivo primario, Se examinaron 265 biopsias de pacientes con lesiones sospechosas de leishmaniasis de la costa Pacífica y región suroriental colombiana. a 1983 (72.8%) pacientes se les estableció el diagnóstico por métodos clínicos y/o poarasitológicos. Los resultados obtenidos por la inmunoperoxidasa en el grupo de pacientes a los cuales se les confirmó la leishmaniasis se compararn con la histopatología convencional, el examen directo de frotis y el aislamiento del parásito por cultivo del aspirado de la lesión. La localización inmunoenzimática de las amastigotas fue más efectivas (61.3%) que la histopatología com hematoxilina y eosina (34.6%), y que el frotis (43,9%). En cambio, el cultivo de aspirado fue más sensible (89.8%). La eficiencia del método de inmunoperoxidasa fue mayor en las lesiones recientes (72.5%) positivos en los casos con menos de tres meses de evolución) que en las lesiones más antiguas (55.6, 37.5 y 21.1% para 3-5.9, 6-11 meses y mayores o iguales a 12 mese, respectivamente). La combinación de frotis e inmunoperoxidasa incrementó el porcentaje de caso diagnosticados a 72.0%, lo que indica la importancia de combinar métodos para obtener una mayor eficiencia de diagnóstico. La especificidad fue de 100% en controles sanos y 92.9% en pacientes con lesiones causadas por agentes etiológicos distintos a leishmania.

Evaluation of antibody responses in american visceral leishmaniasis by ELISA and immunoblot

American visceral leishmaniasis (AVL) is an important disease among children of northeast Brazil. In order to characterize antibody responses during AVL, sera of hospitalized patients were analyzed by ELISA and Western blot using a Leishmania chagasi antigen preparation. The ELISA was positive (asorbance [greater than or equals to] 0.196) at a serum dilution of 1:1024 in all patients at presentation, and fell to ward control levels over the following year. Only one of 72 control subjects tested positive, and that donor had a sibling with AVL. Immunoblots of the patients' sera recognized multiple bands, the most frequent of which were at approximately 116 kDa, 70 kDa, and 26 kDa. Less frenquently observed were bands at approximately 93 kDa, 74 kDa, 62 kDa, 46 kDa and 32 kDa. The ELISA responses and patterns of banding were distinctive for AVL, and could be used to differentiate patients with AVL from those with Chagas' disease of cutaneous leishmaniasis. Sera from six AVL patients followed for up to six weeks after treatment identified no new bands. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of surface iodinated parasite proteins showed one major band and four minor bands, whereas SDS-PAGE of biotinylated prarasite proteins revealed a banding pattern similar to those of patient sera. AVL appears to produce characteristic immunoblot patterns which can be used along with a sensitive screening ELISA to diagnose AVL.