Asymptomatic Leishmania chagasi Infection in Relatives and Neighbors of Patients with Visceral Leishmaniasis

The frequency of asymptomatic infection among relatives and neighbors of cases of visceral leishmaniasis (VL) was compared and characterization of the immunological response in these subjects was performed. Cases were from a new endemic area, close to the beach and near Salvador, capital of the State of Bahia, Brazil. The characterization of asymptomatic infection was made using a skin reaction test and detection of antibody to Leishmania chagasi by the ELISA test. To characterize the immunological response of these subjects with asymptomatic L. chagasi infection the cytokines profile and the lymphoproliferative response were determined after stimulation of lymphocytes by L. chagasi antigen. There was no difference in the frequency of L. chagasi infection in relatives (45%) and in neighbors (27%) of cases of VL (P>0.05). The immunological response from these subjects was characterized by high production of IFN-g and a low production of IL-10 and a good lymphoproliferative response to L. chagasi antigen

Immunological system and Schistosoma mansoni: co-evolutionary immunobiology. What is the eosinophil role in parasite-host relationship?

Schistosomes, ancestors and recent species, have pervaded many hosts and several phylogenetic levels of immunity, causing an evolutionary pressure to eosinophil lineage expression and response. Schistosoma mansoni adult worms have capitalized on the apparent adversity of living within the mesenteric veins, using the dispersion of eggs and antigens to other tissues besides intestines to set a systemic activation of several haematopoietic lineages, specially eosinophils and monocytes/macrophages. This activation occurs in bone marrow, spleen, liver, lymph nodes, omental and mesenteric milky spots (activation of the old or primordial and recent or new lymphomyeloid tissue), increasing and making easy the migration of eosinophils, monocytes and other cells to the intestinal periovular granulomas. The exudative perigranulomatous stage of the periovular reaction, which present hystolitic characteristics, is then exploited by the parasites, to release the eggs into the intestinal lumen. The authors hypothesize here that eosinophils, which have a long phylogenic story, could participate in the parasite - host co-evolution, specially with S. mansoni, operating together with monocytes/ macrophages, upon parasite transmission.

Clinical, Parasitological and Immunological Aspects of Experimental Infection with Trypanosoma evansi in Dogs

This research investigated the pattern of antibody response by means of enzyme linked immunosorbent assay (Elisa) and indirect fluorescent antibody test (IFAT) through the course of experimental Trypanosoma evansi infection in dogs. Clinical and parasitological features were also studied. The average prepatent period was 11.2 days and parasitaemia showed an undulating course. Biometrical study of parasites revealed a mean total length of 21.68mm. The disease was characterized by intermittent fever closely related to the degree of parasitaemia and main clinical signs consisted of pallor of mucous membrane, edema, progressive emaciation and enlargement of palpable lymph nodes. Diagnostic antibody was detected within 12 to 15 days and 15 to 19 days of infection by IFAT and Elisa, respectively. High and persistent antibody levels were detected by both tests and appeared not to correlate with control of parasitaemia

Immunological evaluation of human immunedeficiency virus infected individuals by flow cytometry

Human immunodeficiency virus (HIV) infection heavily compromises the immune system. The decrease of the T cell CD4+ subset along the evolution to acquired immunodeficiency syndrome has been considered as a hallmark of HIV infection. In this paper we review some aspects of the immunopathology of HIV infection and discuss the importance of the flow cytometry for the evaluation of the T lymphocyte subsets in the follow-up of HIV infected children and adults, and for the monitoring of the immune reconstitution upon antiretroviral therapy.

Immunochemotherapy in American cutaneous leishmaniasis: immunological aspects before and after treatment

In this study, we evaluated the immune response of patients suffering from cutaneous leishmaniasis treated with two distinct protocols. One group was treated with conventional chemotherapy using pentavalent antimonium salts and the other with immunochemotherapy where a vaccine against cutaneous leishmaniasis was combined with the antimonium salt. Our results show that, although no differences were observed in the necessary time for complete healing of the lesions between the two treatments, peripheral blood mononuclear cells from patients treated by chemotherapy showed smaller lymphoproliferative responses at the end of the treatment than those from patients in the immunochemotherapy group. Furthermore, IFN-gamma production was also different between the two groups. While cells from patients in the chemotherapy group produced more IFN-gamma at the end of treatment, a significant decrease in this cytokine production was associated with healing in the immunochemotherapy group. In addition, IL-10 production was also less intense in this latter group. Finally, an increase in CD8+ -IFN-gamma producing cells was detected in the chemotherapy group. Together these results point to an alternative treatment protocol where healing can be induced with a decreased production of a potentially toxic cytokine.

Immunological follow-up of hydatid cyst cases

Hydatid disease is caused by Echinococcus granulosus. In this study, we aimed to investigate the benefit of monitoring cases with hydatid cyst by means of immune components in patients in a long-term follow-up after surgery. Eighty-four preoperative and postoperative serum samples from 14 cases undergoing surgery for hydatid disease were evaluated in terms of immune parameters, such as total and specific IgE, IgG, IgM, IgA and complement. Total and specific IgE were determined by ELISA. Specific IgG levels were measured by indirect hemaglutination.Total IgG, IgM, IgA and complement (C3 and C4) were detected by nephelometry. Imaging studies were also carried out during the follow-up. In none of the patients hydatid cysts were detected during the follow-up. Total IgE levels in the sera of the patients decreased to normal six months after surgery. Although specific IgE against echinococcal antigens decreased one year after operation, levels were still significantly high. There were no changes in the levels of anti-Echinococcus IgG and total IgG in follow-up period. Additionally, other parameters, such as IgA, IgM, C3 and C4, were not affected.

Epidemiological and immunological aspects of human visceral leishmaniasis on Margarita Island, Venezuela

Sixty-five patients were diagnosed with visceral leishmaniasis (VL) on Margarita Island in the decade from 1990 to1999; 86.2% were <= 3 years old. All were leishmanin-negative at diagnosis. Evaluation of 23 cured patients in 1999 revealed that 22/23 had converted to leishmanin-positive; five had persisting antibodies to rK39 antigen, with no clinical evidence of disease. Leishmanin tests were positive in 20.2% of 1,643 healthy individuals from 417 households in endemic areas. Of the positive reactors, 39.8% were identified in 35 (8.4%) of the households, 15 of which had an antecedent case of VL, a serologically positive dog or both. Weak serological activity to rK39 antigen was detected in 3 of 488 human sera from the endemic areas. The presence of micro-foci of intense peri-urban transmission and the apparent absence of other Trypanosomatidae causing human disease offer a unique opportunity for the study of reservoirs, alternative vectors and evaluation of control measures on the Island.

Comparative immunological recognition of proteins from New Guinea "C" dengue virus type 2 prototype and from a dengue virus type 2 strain isolated in the State of Rio de Janeiro, Brazil

The protein profiles of the New Guinea "C" dengue virus type 2 (DENV-2)prototype and those of a Brazilian DENV-2 isolated in the State of Rio de Janeiro in 1995 were compared. SDS-PAGE analysis showed that the virus from Rio de Janeiro expresses NS5 (93.0 kDa), NS3 (66.8 kDa) E (62.4 kDa) and NS1 (41.2 kDa) proteins differently from the New Guinea "C" virus. The immunoblot revealed specificity and antigenicity for the NS3 protein from DENV-2 Rio de Janeiro mainly in primary infections, convalescent cases, and in secondary infections in both cases and only antigenicity for E and NS1 proteins for both viruses in primary and secondary infections.

Pulmonary tuberculosis: evaluation of interferon-gamma levels as an immunological healing marker based on the response to the Bacillus Calmette-Guerin

Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis whose interaction with the host may lead to a cell-mediated protective immune response. The presence of interferon-g (IFN-gamma) is related to this response. With the purpose of understanding the immunological mechanisms involved in this protection, the lymphoproliferative response, IFN-g and other cytokines like interleukin (IL-5, IL-10), and tumor necrosis factor alpha (TNF-a) were evaluated before and after the use of anti-TB drugs on 30 patients with active TB disease, 24 healthy household contacts of active TB patients, with positive purified protein derivative (PPD) skin tests (induration > 10 mm), and 34 asymptomatic individuals with negative PPD skin test results (induration < 5 mm). The positive lymphoproliferative response among peripheral blood mononuclear cells of patients showed high levels of IFN-g, TNF-a, and IL-10. No significant levels of IL-5 were detected. After treatment with rifampicina, isoniazida, and pirazinamida, only the levels of IFN-g increased significantly (p < 0.01). These results highlight the need for further evaluation of IFN-g production as a healing prognostic of patients treated.

Immunological tolerance to pig-serum partially inhibits the formation of septal fibrosis of the liver in Capillaria hepatica-infected rats

Systhematized septal fibrosis of the liver can be induced in rats either by repeated intraperitoneal injections of pig-serum or by Capillaria hepatica infection. The relationship between these two etiological factors, as far as hepatic fibrosis is concerned, is not known, and present investigation attempts to investigate it. C. hepatica-induced septal fibrosis of the liver was considerably inhibited in rats previously rendered tolerant to pig-serum. Pig-serum-tolerant rats developed antibodies against pig-serum when infected with C. hepatica, but this did not happen when the infection occurred in normal rats. On the other hand, anti-C. hepatica antibodies failed to recognize any epitope in pig-serum, by Western blot. However, no evidence of an immunological cross reactivity was found, at least at the humoral level. Alternatively, cell-mediated mechanisms may be involved, and further investigations are warranted.

Clinical and immunological consequences of human T cell leukemia virus type-I and Schistosoma mansoni co-infection

Human T cell leukemia virus type-I (HTLV-I) infection is associated with spontaneous T cell activation and uncontrolled lymphocyte proliferation. An exacerbated type-1 immune response with production of pro-inflammatory cytokines (interferon-gamma and tumor necrosis factor-alpha) is significantly higher in patients with myelopathy associated to HTLV-I than in HTLV-I asymptomatic carriers. In contrast with HTLV-I, a chronic Schistosoma mansoni infection is associated with a type-2 immune response with high levels of interleukin (IL-4, IL-5, and IL-10) and low levels of IFN-gamma. In this study, clinical and immunological consequences of the HTLV-I and S. mansoni infection were evaluated. The immune response in patients with schistosomiasis co-infected with HTLV-I showed low levels of IL-5 (p < 0.05) in peripheral blood mononuclear cells cultures stimulated with S. mansoni antigen (SWAP) and decreased SWAP-specific IgE levels when compared with patients with only schistosomiasis (p < 0.05). Liver fibrosis was mild in all HTLV-I co-infected patients. Immunological response was also compared in individuals who had only HTLV-I infection with those who were co-infected with HTLV-I and helminths (S. mansoni and Strongyloides stercoralis). In patients HTLV-I positive co-infected with helminths the IFN-gamma levels were lower than in individuals who had only HTLV-I. Moreover, there were fewer cells expressing IFN-gamma and more cells expressing IL-10 in individuals co-infected with HTLV-I and helminths. These dates indicate that HTLV-I infection decrease type 2-response and IgE synthesis and are inversely associated with the development of liver fibrosis. Moreover, helminths may protect HTLV-I infected patients to produce large quantities of pro-inflammatory cytokines such as IFN-gamma.

Further observations on clinical, histopathological, and immunological features of borderline disseminated cutaneous leishmaniasis caused by Leishmania (Leishmania) amazonensis

Leishmania (Leishmania) amazonensis has for some time been considered as the causative agent of two distinct forms of American cutaneous leishmaniasis (ACL): localized cutaneous leishmaniasis (LCL), and anergic diffuse cutaneous leishmaniasis (ADCL). Recently, a new intermediate form of disease, borderline disseminated cutaneous leishmaniasis (BDCL), was introduced into the clinical spectrum of ACL caused by this parasite, and in this paper we record the clinical, histopathological, and immunological features of eight more BDCL patients from Brazilian Amazonia, who acquired the disease in the Pará state, North Brazil. Seven of them had infections of one to two years' evolution and presented with primary skin lesions and the occurrence of metastases at periods varying from six to 12 months following appearance of the first lesion. Primary skin lesions ranged from 1-3 in number, and all had the aspect of an erythematous, infiltrated plaque, variously located on the head, arms or legs. There was lymphatic dissemination of infection, with lymph node enlargement in seven of the cases, and the delayed hypersensitivity skin-test (DTH) was negative in all eight patients prior to their treatment. After that, there was a conversion of DTH to positive in five cases re-examined. The major histopathological feature was a dermal mononuclear infiltration, with a predominance of heavily parasitized and vacuolated macrophages, together with lymphocytes and plasma cells. In one case, with similar histopathology, the patient had acquired his infection seven years previously and he presented with the largest number of disseminated cutaneous lesions. BDCL shows clinical and histopathological features which are different from those of both LCL and ADCL, and there is a good prognosis of cure which is generally not so in the case of frank ADCL.

Changes induced in Biomphalaria glabrata (Say, 1818) following trials for artificial stimulation of its internal defense system

Biomphalaria glabrata can react through different pathways to Schistosoma mansoni miracidium penetration, according to the degree of resistance/susceptibility presented by different snail strains, which is a genetically determined character, resistance being the dominant feature. However, it has been observed that previous susceptible snail strain may change its reactive behavior along the course of infection, exhibiting later a pattern of cercarial shedding and histopatopathological picture compatible with high resistance. Such observation suggests the possibility of B. glabrata to develop a sort of adaptative immunity face a schistosome infection. To explore on this aspect, the present investigation looked for the behavior of S. mansoni infection in B. glabrata previously subjected to different means of artificial stimulation of its internal defense system. Snails previously inoculated with irradiated miracídia (Group I); treated with S. mansoni antigens (Group II) or with a non-related parasite antigen (Group III) were challenged with 20 viable S. mansoni miracidia, and later looked for cercarial shedding and histopathologic changes at different times from exposition. Nodules of hemocyte accumulations were found at the site of antigen injection. These nodules resembled solid granulomas, and were larger and more frequent in snails injected with S. mansoni products as compared to those injected with Capillaria hepatica. However, the presence of such granulomas did not avoid the S. mansoni challenge infection from developing in a similar way as that seen in controls. The data are indicative that hemocytes are able to proliferate locally when stimulated, such capacity also remaining localized, not being shared by the population of hemocytes located elsewhere within the snail body.

Immunological and microbiological activity of Davilla elliptica St. Hill. (Dilleniaceae) against Mycobacterium tuberculosis

Mycobacterium tuberculosis is responsible for over 8 million cases of tuberculosis (TB) annually. Natural products may play important roles in the chemotherapy of TB. The immunological activity of Davilla elliptica chloroform extract (DECE) was evaluated in vitro by the determination of hydrogen peroxide (H2O2), nitric oxide (NO), and tumor necrosis factor-alpha (TNF-alpha) release in peritoneal macrophages cultures. DECE was also tested for its antimycobacterial activity against M. tuberculosis using the microplate alamar blue assay. DECE (50, 150, 250 µg/ml) stimulated the production of H2O2 (from 1,79 ± 0,23 to 7,27 ± 2,54; 15,02 ± 2,86; 20,5 ± 2,1 nmols) (means ± SD), NO (from 2,64 ± 1,02 to 25,59 ± 2,29; 26,68 ± 2,41; 29,45 ± 5,87 µmols) (means ± SD) and TNF-alpha (from 2,44 ± 1,46 to 30,37 ± 8,13; 38,68 ± 1,59; 41,6 ± 0,90 units/ml) (means ± SD) in a dose-dependent manner and also showed a promising antimycobacterial activity with a minimum inhibitory concentration of 62,5 µg/ml. This plant may have therapeutic potential in the immunological and microbiological control of TB.