Protective CD8+ T cell responses against the pre-erythrocytic stages of malaria parasites: an overview

CD8+ T cells have been implicated as critical effector cells in protection against the pre-erythrocytic stage of malaria in mice and humans following irradiated sporozoite immunization. Immunization experiments in animal models by several investigators have suggested different strategies for vaccination against malaria and many of the targets from liver stage malaria antigens have been shown to be immunogenic and to protect mice from the sporozoite challenge. Several prime/boost protocols with replicating vectors, such as vaccinia/influenza, with non-replicating vectors, such as recombinant particles derived from yeast transposon (Ty-particles) and modified vaccinia virus Ankara, and DNA, significantly enhanced CD8+ T cell immunogenicity and also the protective efficacy against the circumsporosoite protein of Plasmodium berghei and P. yeti. Based on these experimental results the development of a CD8+ T cell inducing vaccine has moved forward from epitope identification to planning stages of safety and immunogenicity trials of candidate vaccines

Modern immunological approaches to assess malaria transmission and immunity and to diagnose plasmodial infection

The present paper reviews our recent data concerning the use of immunological methods employing monoclonal antibodies and synthetic peptides to study malaria transmission and immunity and to diagnose plasmodial infection. As concerns malaria transmission, we studied the main vectors of human malaria and the plasmodial species transmitted in endemic areas of Rondônia state, Brazil. The natural infection on anopheline was evaluated by immunoradiometric assay (IRMA) using monoclonal antibodies to an immunodominant sporozoite surface antigen (CS protein) demonstrated to be species specific. Our results showed that among six species of Anopheles found infected, An. darlingi was the main vector transmitting Plasmodium falciparum and P. vivax malaria in the immediate vicinity of houses. In order to assess the level of anti-CS antibodies we studied, by IRMA using the synthetic peptide corresponding to the repetitive epitope of the sporozoite CS protein, sera of individuals living in the same areas where the entomological survey has been performed. In this assay the prevalence of anti-CS antibodies was very low and did not reflect the malaria transmission rate in the studied areas. In relation to malaria diagnosis, a monoclonal antibody specific to an epitope of a 50 kDa exoantigen, the major component of supernatant collected at the time of schizont rupture, was used as a probe for the detection of P. falciparum antigens. This assay seemed to be more sensitive than parasitological examination for malaria diagnosis since it was able to detect plasmodial antigens in both symptomatic and asymtomatic individuals with negative thick blood smear at different intervals after a last parasitologically confirmed confirmed attack of malaria

Immunological abnormalities of acquired immunodeficiency syndrome and related disorders in patients from Rio de Janeiro, Brazil

Alteraçöes imunológicas na Síndrome de Imunodeficiência Adquirida em pacientes do Rio de Janeiro, Brasil. O perfil imunológico de 15 pacientes com Síndrome de Imunodeficiência Adquirida (AIDS) e 11 com Síndrome de Linfadenipatia Crônica, foram estudados. Os pacientes com AIDS mostraram reduzida percentagem de linfócitos T (CD3) totais e T auxiliares (CD4), aumento relativo no número de linfócito T-supressores (CD8) e uma marcante inversäo na relaçäo T-auxiliares/supressores (CD4/CD8). A resposta linfoproliferativa para PHA, ConA, PPD e PWN, estava diminuída. Foi também observado hipergamaglobulinemia e níveis aumentados de complexos imunes circulantes. Os pacientes com Síndrome de Linfadenopatia Crônica também mostraram importantes alteraçöes imunológicas, mas näo täo intensas como nos de AIDS. Estes dados säo similares aos observados nos Estados Unidos e na Europa (U)

Proteção do miocárdio em cirurgia cardíaca. Estudo experimental / Myocardial protection in heart surgery. Experimental study

Os autores realizaram estudo experimental em 15 caes, submetidos a cirurgia cardiaca com circulacao extracorporea e divididos em 3 grupos: grupo I (controle): parada cardiaca anoxica; grupo II (cardioplegia-eletrolitos): parada cardiaca induzida por solucao de eletrolitos a 4oC; grupo III (cardioplegia-eletrolitos, lidocaina, verapamil): parada cardiaca induzida por soluto glicosado, eletrolitos, lidocaina e verapamil. Foram feitas biopsias antes e apos a parada cardiaca de 60 minutos, para microscopia otica e eletronica.Nao se observaram alteracoes a microscopia optica em nenhum dos grupos. O estudo ultra-estrutural mostrou o seguinte: grupo I: edema das mitocondrias e do conjunto perivascular; grupo II: edema das mitocondrias, ruptura das cristas, edema intracelular, ausencia de glicogenio; grupo III: preservacao das mitocondrias, dos granulos de glicogenio e da arquitetura da celula miocardica. Os autores concluiram que a melhor preservacao da estrutura miocardica foi verificada no grupo III