The concomitant immunity in the presence of repeated infections (with 15 cercariae) was studied in mice sacrificed on the 20th day after each infection. The comparison of the averages of immature worms, recovered from mice submitted to reinfection, with those of their respective controls (previously uninfected) showed a significantly lower worm recovery rate in the animals with previous infections (concomitant immunity). However, statiscally significant differences could not be detected among the various groups of animals, when the mice that accumulated worms in this mature stage were perfused. The theoretical projection based on the accumulation of young worms which developed to adult ones indicates a lower recovery rate of adult worms in the animals with concomitant immunity, but this projection was not corroborated by the experimental data. The visceral hemodynamic alterations that occurred in reinfections due to the pathogeny, favouring recirculation of the recent arriving worms to the other organs on the occasion of perfusion of the portal system. These results suggest that special care should be taken when one wants to investigate concomitant immunity in mice based on the distinction of the immature worms from challenge infection and the mature ones from primary infection.

No presente estudo, verificou-se o comportamento histopatológico das infecções e reinfecções, homólogas ou heterólogas, das cepas LE (Belo Horizonte, MG) e SJ (São José dos Campos, SP) de Schistosoma mansoni. Confirmou-se uma maior patogenicidade da cepa SJ de S. mansoni. As reinfecções, independentemente de terem sido feitas com a mesma cepa (homóloga) ou cepa diferente da primo infecção (heteróloga) do parasito, mostraram a presença de granulomas típicos da fase aguda. São discutidos os possíveis mecanismos responsáveis pela reagudização da resposta imunopatológica nas reinfecções.

In this study, which was undertaken in relation to the histopathologic behavior of two different strains (LE-Belo Horizonte, MG and SJ - São José dos Campos, SP) in infections and reinfections (homologous or heterologous) with Schistosoma mansoni, the authors confirmed a more accentuated pathogenicity of the SJ strain. All the reinfections showed the presence of typical granulomas of the acute phase, when performed either with the same strain (homologous) or with a different strain (heterologous) of the parasite of the primo infection. The possible mechanisms responsible for reactivation of the immunopathologic response in reinfections are discussed.

Para verificar a capacidade de modulação da resposta granulomatosa na esquistossomose murina, após cura quimioterápica, camundongos previamente infectadosforam curados com oxamniquina (400mg/kg, p. o.) e reinfectados 20 dias após tratamento. O exame histopatológico do fígado dos animais, aos 60 dias após reinfecção, mostrou, na maioria deles, a presença de granulomas nafase produtiva, típicos da fase crônica da doença, pertnitindo a inferência de que a capacidade de modulação da resposta granulomatosa foi mantida, prevenindo assim uma outra fase aguda da doença. Por outro lado, um grupo de camundongos previamente infectados e submetidos a reinfecção mostrou a reagudização da resposta granulomatosa em 50% dos animais. As possíveis implicações destes achados na esquistossomose mansoni humana são discutidas.

Mice previously infected with Schistosoma mansoni, and cured by specific treatment (400mg/kg oxamniquine, p. o.) in the chronic phase of the disease, were reinfected 20 days after treatment to assess their capacityfor modulation ofthe granulomatous response. Histopathologic examination of the animals ' liver, at 60 days after reinfection, evidenced the presence of typical granulomas of the chronic phase in most animals. This infer that the capacity for modulation of the granulomatous response had been maintained, thus preventing a new acute phase of the disease. Conversely, a group of previously infected mice, untreated and submitted to reinfection, showed reactivation of the granulomatous response in 50% of the animals. The possible implications of these findings in human schistosomiasis mansoni are discussed.

Três bezerros, experimentalmente infectados com Schistosoma mansoni e passando ovos viáveis nas fezes, bem como 5 bezerros normais, oriundos de área não endêmica para esquistossomose e usados como controles, foram mantidos em uma área fechada de 850 m². Nesta área, foram colocados em um tanque com água 500 caramujos Biomphalaria glabrata criados em laboratório. Todos os bezerros controles foram infectados por um período de 79 a 202 dias após o começo do experimento e, mais tarde, apresentaram ovos viáveis de S. mansoni nas fezes. A recuperação média de vermes foi de 538. A população de moluscos aumentou durante o período experimental, mostrando um número significativo de B. glabrata infectados com S. mansoni (42% em média). De acordo com o resultado do presente trabalho, que foi conduzido em condições experimentais, foi sugerido que bovinos tem, potencialmente, um papel na manutenção do ciclo vital do S. mansoni

Three calves experimentally infected with Schistosoma mansoni, and passing viable eggs in feces, as well as 5 normal calves (coming from a non-endemic area for schistosomiasis) kept as controls, were maintained in an enclosure (850 m² in area). In this enclosure, a tank with water received 500 laboratory reared Biomphalaria glabrata. All the control calves were infected for a period ranging from 79 to 202 days after the beginning of the experiment, and afterwards presented viable S. mansoni eggs in feces. The mean worm recovery was 555. The snail population increased throughout the experimental period, showing a high number of B. glabrata infected with S. mansoni (42% on average). According to the present study, bovine has been suggested as having potentially a role in the maintenance of the life cycle of S. mansoni

Camundongos infectados com 350 cercárias de Schistosoma mansoni (cepa LE) foram tratados com oxamniquina, em dose única de 400 mg/kg, 24,48,72 e 96 horas após a infecção. Quarenta dias após o tratamento, os animais foram submetidos a uma infecção desafio com 80 cercárias, através da pele abdominal e da orelha. O número de vermes imaturos nos grupos de animais tratados 24 e 96 horas após a primeira infecção foi menor do que o do grupo controle, evidenciando que a morte de esquistossômulos por quimioterapia, durante as fases da pele e do pulmão, causa um estado de resistência adquirida.

Mice infected with 350 cercariae of Schistosoma mansoni (LE strain) were treated with oxamniquine, at the dose of 400 mg/kg, 24, 48, 72, and 96 h after infection. Forty days after the treatment, the animals were submitted to a challenge infection with 80 cercariae, through the abdominal and ear skins. The number of immature worms in the animal groups treated 24 and 96 h after the first infection was found to be lower than that in the control group, thus showing that the death of schisto-somes by chemotherapy, at the skin and pulmonary phases, causes an acquired resistance state.

Os autores determinaram o diâmetro médio dos granulomas de fígado de camundongos infectados com cercárias de duas cepas geográficas bem definidas do, Schistosoma mansoni (LE, Belo Horizonte e SJ, São Paulo). No total foram medidos 1.170 granulomas. Os granulomas com 60 dias eram de dimensões maiores do que os de 90 dias. A modulação da resposta imunopatológica foi significativamente mais eficiente na cepa LE e os granulomas, tanto aos 60 como aos 90 dias, da cepa SJ eram significativamente maiores. Os dados obtidos indicam uma maior patogenicidade da cepa SJ. Especula-se se o significado destes achados poderiam, em parte, explicar a ocorrência das variações regionais das formas anatomo-clínicas da esquistossomose.

The authors have determined the mean diameter of granulomas in the liver of mice infected with cercariae from two different and well definite geographic strains of Schistosoma mansoni (LE, Belo Horizonte, MG, and SJ, São José dos Campos, SP). A total of 1,170 granulomas has been measured. Granulomas measured on the 60th day after infection showed larger size than the other ones measured on the 90th day. Modulation of the immunopathologic response was significantly more efficient for the LE strain, whereas the granulomas ( with 60 and 90 days) related to SJ strain were significantly larger. Data suggested a higher pathogenicity for the SJ strain. It is speculated whether these findings could explain, in part, the occurence of regional variations of the anatomo-clinical forms of schistosomiasis.

In two distinct experiments, immature S. mansoni worms (LE strain, Belo Horizonte, Brazil), aged 20 days, obtained from the portal system of white outbred mice, were irradiated with 14 and 4 Krad, respectively. Afterwards, the worms were directly inoculated into the portal vein of normal mice. Inoculation was performed with 20 irradiated worms per animal. Fifty days after inoculation, the mice that received 4 and 14 Krad-irradiated worms and their respective controls were infected with S. mansoni cercariae (LE strain), by transcutaneous route. Twenty days after this challenge infection, the animals were sacrificed and perfused for mature irradiated (90-day-old) and immature (20-day-old) worm counts. Analysis of the results showed that statistically significant protection against cercariae occurred in both groups with irradiated worms.

Tentou-se obter imunoproteção contra infecção cercariana pela inoculação de vermes vivos na cavidade peritoneal de camundongos. Embora os vermes sobrevivessem bem nestas condições e não ocorresse postura de ovos, não foi possível obter imunoproteção, Também a inoculação de ovos viáveis por via sangüínea e peritoneal não propiciou o aparecimento de imunoproteção nos camundongos com vermes na cavidade peritoneal.

An attempt has been made to induce immunoprotection against cercarial infection through inoculation of live worms into the peritoneal cavity of mice. Although the worms were able to survive normally under these conditions, and no egg-laying could be detected, immunoprotection was obtained. Likewise, the inoculation of viable eggs, by circulatory and peritoneal routes, did not provide immunoprotection in mice with worms in the peritoneal cavity.

The post-treatment pulmonary alterations were evaluated in patients (Study 1) and in mice (Study 2) infected with Schistosoma mansoni. Study 1: the patients were examined pre and post-treatment (with ora oxamniquine) and the following exams were performed: sputum for eosinophils and chest x-ray. Study 2: four groups of mice (total = 64) were studied; Group I (infected and treated with oxamniquine); II (infected and not treated); III (not infected and treated) and IV (not infected and not treated). All were x-rayed to check for pulmonary abnormalities pre and post-treatment and lung specimens were studied by optical microscopy and immunofluorescence. We have found abnormalities in the parameters checked in both studies and the results suggest an immunological reaction, probably due to deposition of immune complexes in the lungs, with subsequent activation of the complement system. The experimental study showed that the alterations are not dependent of the presence of eggs and/or worms of S. mansoni in the lungs, thus corroborating the hypothesis of deposition of circulating material.

Camundongos experimentalmente infectados com Schistosoma mansoni foram injetados com tiopental sódico ou antimonial (TriostibR), ou submetidos à inalação de halotano, com ou sem uma injeção prévia de tiopental. Os resultados mostraram que o halotano e o tiopental induzem, respectivamente, o deslocamento de 99 e 76% dos vermes para o fígado. Gluconato de sódio e antimonio (Triostib R) deslocou 52% de vermes. Estes resultados parecem indicar que o uso de antimonial seria desnecessário quando se faz a remoção cirúrgica de esquistossomos pela técnica de filtração extracorpórea em pacientes com hipertensão portal.

Mice experimentally infected with Schistosoma mansoni were injected with sodium thiopental or sodium antimonyl gluconate (Triostib R), or submitted to halothane inhalation, with or without a previous injection of thiopental. Data obtained showed that halothane and thiopental induce worm shift to the liver (99 and 76%, respectively). Sodium gluconate and antimonium (Triostib R) shifted 52% of worms towards the liver. These results seem to indicate that the use of antimonium would be unnecessary, when surgical removal of schistosomules is carried out through the extracorporeal filtration technique, in patients with portal hypertension.

Esquistossômulos com 14 dias de idade, obtidos de camundongos previamente infectados, foram cirurgicamente transferidos para a veia porta de camundongos receptores. Outro grupo de camundongos foi infectado com cercárias por via transcutânea. Noventa dias após, aqueles grupos foram desafiados com 100 cercárias, transcutaneamente, assim como o grupo controle. Duas semanas mais tarde, os animais foram perfundidos e os vermes — maduros e imaturos — contados separadamente. Diferenças estatisticamente significativas foram observadas na recuperação dos vermes imaturos, quando o grupo controle foi comparado com aqueles grupos infectados duas vezes. Nenhuma diferença estatística foi detectada entre o grupo infectado transcutaneamente e o grupo infectado por inoculação do verme na veia porta. Os resultados demonstraram que a supressão da migração do parasito através da pele e dos pulmões não interfere no desenvolvimento da chamada imunidade concomitante.

Fourteen-day-old schistosomula obtained from mice previously infected were surgically transferred to the portal vein of receptor mice. Another group of mice was infected with cercariae by transcutaneous route. After 90 days, those groups were challenged with 100 cercariae, transcutaneously, as well as a control group. Two weeks later the animals were perfused and mature and immature worms counted separately. Statistically significant differences were observed in the recovery of immature worms, when the control group was compared with those twice infected. No statistical difference was detected between the group infected transcutaneously, and that infected by worm inoculation in portal vein. Results demonstrated that suppression of skin and lung migration of the parasite does not interfere with the development of the so called concomitant immunity.