Experimental pulmonary schistosomiasis: lack of morphological evidence of modulation in schistosomal pulmonary granulomas

Numerous pulmonary schistosome egg granulomas were present in mice submitted to partial portal vein ligation (Warren's model). The granulomas were characterized by cellular aggregations formed within alveolar tissue. Main cellular types were macrophages (epithelioid cells), eosinophils, plasma cells and lymphocytes. These cells were supported by scanty fibrous stroma and exhibited close membrane contact points amongst themselves, but without forming specialized adhesion apparatus. When granulomas involved arterial structures, proliferation of cndothelial and smooth muscle cells occurred and fibrosis associated with angiogenesis became more evident. Granulomas formed around mature eggs in the pulmonary alveolar tissue presented approximately the same size and morphology regardless of the time of infection, the latter being 10, 18 and 25 weeks after cercarial exposure. This persistence of morphological appearance suggests that pulmonary granulomas do not undergo immunological modulation, as is the case with the granulomas in the liver and, to a lesser extent, in the intestines. Probably, besides general immunological factors, local (stromal) factors play an important role in schistosomal granuloma modulation.

Prevalence of rubella antibodies in a non-immunized urban population, São Paulo, Brazil

The prevalence of rubella antibodies was evaluated through a ramdom Seroepidemiological survey in 1400 blood samples of 2-14 year old children and in 329 samples of umbilical cord serum. Rubella IgG antibodies were detected by ELISA, and the sera were collected in 1987, five years before the mass vaccination campaign with measles-mumps-rubella vaccine carried out in the city of São Paulo in 1992. A significant increase in prevalence of rubella infection was observed after 6 years of age, and 77% of the individuals aged from 15 to 19 years had detectable rubella antibodies. However, the seroprevalence rose to 90.5% (171/189) in cord serum samples from children whose mothers were 20 to 29 years old, and reached 95.6% in newborns of mothers who were 30 to 34 years old, indicating that a large number of women are infected during childbearing years. This study confirms that rubella infection represents an important Public Health problem in São Paulo city. The data on the seroprevalence of rubella antibodies before the mass vaccination campaign reflects the baseline immunological status of this population before any intervention and should be used to design an adequate vaccination strategy and to assess the Seroepidemiological impact of this intervention.

Cell and humoral immunity in endemic pemphigus foliaceus

A study was conducted on 16 patients with pemphigus foliaceus, ten of them with the localized form (group G1) and six with the disseminated form (group G2). These patients were submitted to full blood counts, quantitation of mononuclear cell subpopulations by monoclonal antibodies, study of blastic lymphocyte transformation, and quantitation of circulating antibodies by the indirect immunofluorescence test, in order to correlate their clinical signs and symptoms and laboratory data with their immunological profile, and to determine the relationship between circulating autoantibody titers and lesion intensity and course of lesions under treatment. Leucocytosis was observed especially in group G2. All patients showed decreased relative CD3+ and CD4+ values and a tendency to decreased relative values of the CD8+ subpopulation. Blastic lymphocyte transformation indices in the presence of phytohemagglutinin were higher in patients (group G1+G2) than in controls. The indirect immunofluorescence test was positive in 100% of G2 patients and in 80% of G1 patients. The median value for the titers was higher in group G2 than in group G1. Analysis of the results as a whole permits us to conclude that cell immunity was preserved and that there was a relationship between antibody titers detected by the direct immunofluorescence test and extent of skin lesions.

Seroepidemiological and clinical study of Chagas' disease in Nicaragua

With the aim of determining the prevalence, immunological profile, and knowing the electrocardiographic alterations, a clinical and Seroepidemiological study of Chagas' disease was performed in three rural settlements located at the North, East and West of Nicaragua. Anti T. cruzi antibodies were searched by indirect immunofluorescence (IFI) and hemagglutination (IHA) in a total of 803 subjects. Seropositives and the same number of seronegatives, matched by age and sex, were included in a case-control design for the electrocardiographic assessment. Antibody prevalence was 13.1, 4.3 and 3.2% in the respective settlements. In the first two the immunological profile corresponds to that of an endemic zone of long standing, were transmission has decreased, and in the third the pattern is of a zone under control. Electrocardiographic changes compatible with Chagas' disease were found in seropositive individuals, but difference with control group was not statistically significant. It is concluded that the disease is endemic in the three settlements and the clinical aspect requires further evaluation, including additional cardiologic techniques.

Leishmania (Viannia) panamensis - induced cutaneous leishmaniasis in susceptible and resistant mouse strains

We studied the susceptibility to Leishmania (Viannia) panamensis in strains of mice. The C57BL/6 strain was resistant and showed self-controlled lesion at the injected foot pad. The BALB/c and DBA/2J strains were susceptible and showed a foot swelling that started day 20 post-infection and progressed to a tumour-like lesion in later period of observation. The CBA/HJ strain was found to be of intermediary resistance. In contrast to other known cutaneous leishmaniasis in mice, the lesion in L. (V.) panamensis-infected mice was restricted to the inoculation site in the skin. In addition, we studied the development of cellular response and antibodies against Leishmania antigen in BALB/c and C57BL/6 strains. The proliferative response of lymph node cells against L. (V.) panamensis antigen was biphasic in both strains. An initial response was seen on day 20, followed by a refractory period between 40 and 80 days and a second response around fourth month post-infection. The response in the latter period was higher in C57BL/6 strain than in BALB/c strain. BALB/c strain presented much higher anti-Leishmania antibody level than C57BL/6 strain. The model and the correlation of immunological variables and the course of the infection are discussed.

Human pulmonary dirofilariasis: a review

The authors presented a detailed summary of the geographical distribution, clinical and pathological aspects of human pulmonary dirofilariasis. Although benign, this zoonosis, of which Dirofilaria immitis is the major etiological agent, represents a medical problem since it produces symptoms which may be confused with neoplasia and thus may subject patients to unnecessary thoracic surgery. Of 229 cases cited in the literature, only 17 were reported in Brazil, despite the existence of highly favorable conditions for the transmission of this infection in man. Thus it may well be that this parasitic infection remains underdiagnosed. Finally, the importance of a differential diagnosis between dirofilariasis and pulmonary neoplasia is emphasized in cases where there is a solitary subpleural nodule ("coin lesion") present. In addition, the development and improvement of modern immunological diagnostic techniques are essential to distinguish this benign disease from other pathological conditions and thus avoid unneccessary surgery. These techniques may reveal the true prevalence of this parasitic infection in our environment.

Histoplasmosis in the Muñiz Hospital of Buenos Aires

Some epidemiological and immunological characteristics and the methodology of diagnosis of 44 cases of histoplasmosis (HP); 36 (27 males and 9 women) associated with AIDS (HP+AIDS) and 8 (7 males and 1 female) with other predisposing factors (HP+non AIDS), diagnosed in the Muñiz Hospital (MH) during 1994, were retrospectively studied. The median age (MA) of HP+AIDS patients was 28 years; 25.5 (22-40) in the women and 28.5 (20-42) in the men and 50 (22-58) years in the HP+non AIDS patients. The more frequent risk factors for HIV infection were intravenous drug addiction (55%) and homo/bisexuality (19%). The MA of these groups were 28 (20-39) and 41 (26-42) years, respectively. Tobaccoism was a predisposing factor in 83% of HP+non AIDS patients. The muco-cutaneous lesions scraping and blood-cultures established the initial diagnosis in 53% and 36% of HP+AIDS patients, respectively and the muco-cutaneous lesions biopsies in 75% of HP+non AIDS cases. At time of diagnosis, all HP+AIDS patients had <200 while HP+non AIDS patients had > 200 CD4 + lymphocytes/µl. Seventy two per cent of HP+AIDS patients were born in Buenos Aires (Bs As) city and 62% of HP+non AIDS patients were born in provinces of Argentina other than Bs As. At moment of diagnosis, 87.5% of HP+AIDS and 62.5% of HP+non AIDS patients lived in Bs As city and Bs As outskirts.

Histopathology and immunocytochemical study of type 3 and type 4 complement receptors in the liver and spleen of dogs naturally and experimentally infected with Leishmania (Leishmania) chagasi

The objective of this study was to compare the histopathological changes and expression of CR3 and CR4 in the liver and spleen of dogs naturally and experimentally infected with L. chagasi. The basic histopathological lesions observed mainly in naturally infected dogs were: epithelioid hepatic granulomas, hyperplasia and hypertrophy of Kupffer cells, Malpigui follicles and mononucleated cells of the red pulp of the spleen. Sections from the liver and spleen by immunocytochemistry technique showed the presence of CD11b,c\CD 18 antigens in the control and infected animals and no qualitative or quantitative differences in the liver. Nevertheless, CD18 was always increased in the spleen of naturally and experimentally infected dogs. These results indicate that there is a difference in the activaton of CD 18 in both experimental and natural cases of canine visceral leishmaniasis that should play an important role in the immunological response to Leishmania chagasi infection.

Seropositivity for anti-Trypanosoma cruzi antibodies among blood donors of the "Hospital Universitário Regional do Norte do Paraná", Londrina, Brazil

The most frequent form of acquisition of Chagas' disease in endemic areas was the transmission through the feces of contaminated triatominae. However, special attention should be paid in urban areas to transmission by blood transfusion, justifying the compulsory screening of blood donors. Early investigations at blood banks in the town of Londrina, Brazil, demonstrated that the seroprevalence of anti-Trypanosoma cruzi antibodies among blood donors was approximately 7.0% in the fifties9,34. Further studies demonstrated pratically the same seroprevalence until the eighties4,32,41. In an attempt to obtain data about the real dimension of the seropositivity for anti-Trypasonoma cruzi antibodies in the region, the authors carried out a large-scale study on 45,774 serum samples from blood donors of the Hemocentro of Hospital Universitário Regional do Norte do Paraná (HURNP), Universidade Estadual de Londrina. The immunological tests were done at the Division of Clinical Immunology of HURNP from May 1990 to December 1994. The serum samples were studied by the indirect hemagglutination assay (IHA, using kits commercially obtained from EBRAM) and by indirect immunofluorescence (IFI, using kits from LIO SERUM) with anti-human IgG conjugate (LABORCLIN). The results demonstrated that 643 serum samples were positive in both assay corresponding to a seroprevalence of 1.4%, i.e., a significant decrease in anti-Trypanosoma cruzi antibodies in the region in comparison with the previously mentioned rates. Data correlating sex and age of seropositive blood donors are presented, as well as the possible factors that may have contributed to the results observed.

Candidin: comparison of two antigens for cutaneous delayed hypersensitivity testing

A candidin, which is a suspension of killed yeast cells, is commonly used for intradermal tests of delayed hypersensitivity, to evaluate the immunological cellular competence of the patient, when the test is applied along with other similar tests. When working with a cellular antigen, the histopathology of positive skin tests reveals a cellular infiltrate which not only presents a characteristic hypersensitivity reaction but also a neutrophilic abscess in the central part. This research presents the results of a comparison between the yeast cell suspension and the polysaccharide antigens, both obtained from the same strains of Candida albicans. The results obtained by skin tests in one hundred individuals were 61.0% with the polysaccharide antigen and 69.0% with the yeast cell suspension antigen. Concordant results concerning the two antigens were observed in 82.0% of the individuals. The discussion section presents an assumption to explain the differences of positivity obtained with the two antigens. We conclude that the polysaccharide antigen can be utilized in the intradermal test of delayed hypersensitivity to Candida albicans.

IMMUNOSTIMULATION AS ADJUVANT FOR THE CHEMOTHERAPY OF EXPERIMENTAL SCHISTOSOMIASIS

Immunosuppressed animals respond poorly to schistosomal chemotherapy and that a proper response can be restored by the administration of immune serum. Present study attempts to search whether immunological stimulation would increase drug effectiveness. Swiss mice infected with 50 S. mansoni cercariae were later treated with complete Freund's adjuvant. Treatment with oxaminiquine was made with 100 mg/kg.b.w., 25 mg/kg.b.w. and 50 mg/kg/b.w., the last two doses representing a fourth and a half of the recommended curative dose. Appropriate controls for the drug, the adjuvant and the infection were also studied. The serum-level of ant-S. mansoni antibodies (ELISA) and recovery of worms by perfusion of the portal vein system were the evaluated parameters. Statistical analysis of the results failed to reveal significant differences in worm recovery between adjuvant-stimulated animals treated with oxamniquine and any of the treated controls receiving the same amount of the drug. Although total lack of immunity interferes with curative treament the usual immune response seems to be sufficient to allow for curative drug action in schistosomiasis and thus apparently does not need to be artificially stimulated

EVALUATION OF A RAPID SCREENING ASSAY FOR BACTERIAL IDENTIFICATION (DOT-ELISA) IN FECAL SAMPLES FROM CHILDREN

With the objective of standardizing a Dot Enzyme-Linked Immunosorbent Assay (Dot-ELISA) to detect antigens of fecal bacterial enteropathogens, 250 children, aged under 36 months and of both sexes, were studied; of which 162 had acute gastroenteritis. The efficacy of a rapid screening assay for bacterial enteropathogens (enteropathogenic Escherichia coli "EPEC", enteroinvasive Escherichia coli "EIEC", Salmonella spp. and Shigella spp.) was evaluated. The fecal samples were also submitted to a traditional method of stool culture for comparison. The concordance index between the two techniques, calculated using the Kappa (k) index for the above mentioned bacterial strains was 0.8859, 0.9055, 0.7932 and 0.7829 respectively. These values express an almost perfect degree of concordance for the first two and substantial concordance for the latter two, thus enabling this technique to be applied in the early diagnosis of diarrhea in infants. With a view to increasing the sensitivity and specificity of this immunological test, a study was made of the antigenic preparations obtained from two types of treatment: 1) deproteinization by heating; 2) precipitation and concentration of the lipopolysaccharide antigen (LPS) using an ethanol-acetone solution, which was then heated in the presence of sodium EDTA

HEMAGGLUTINATION TEST FOR THE DIAGNOSIS OF HUMAN NEUROCYSTICERCOSIS: DEVELOPMENT OF A STABLE REAGENT USING HOMOLOGOUS AND HETEROLOGOUS ANTIGENS

A hemagglutination (HA) test was standardized using formalin- and tannin-treated gander red blood cells sensitized with a total salt extract of C. cellulosae (HA-Cc) and an antigenic extract of Cysticercus longicollis (HA-Cl) vesicular fluid. A total of 61 cerebrospinal fluid (CSF) samples were assayed, 41 from patients with neurocysticercosis and 20 from a control group, which were, respectively, reactive and non-reactive to ELISA using C. cellulosae. The CSF samples from the control group did not react and 35 (85.4%) and 34 (82.9%) CSF samples from patients were reactive to the HA-Cc and HA-Cl tests, respectively. The reagents ready for use were stable up to 6 months when stored at 4°C in 50% glycerol. The present results confirm that the reagent using Cysticercus longicollis stabilized with glycerol can be used as an alternative in the immunological diagnosis of neurocysticercosis

PRESENCE OF ANTI-TOXOCARA ANTIBODIES IN CHILDREN SELECTED AT HOSPITAL UNIVERSITÁRIO, CAMPO GRANDE, MS, BRAZIL

Visceral Larva Migrans syndrome (VLM) results from the presence or migration of helminth larvae in humans, who nonetheless only play the role of paratenic hosts in the helminths' life cycle. In humans, VLM can be caused by larvae of various nematode species, chiefly those of the ascarid Toxocara canis, which can then be found at a variety of body sites, such as the liver, lungs, heart, and brain. Clinical and pathological manifestations depend primarily on larvae number and location, infection duration, reinfection occurrence, and host's immunological condition. Signs and symptoms may range from asymptomatic infection to severe disease. In humans, infection is acquired through ingestion of T. canis eggs present in soil, containing larvae in the infective stage7, 8, 9. Indeed, eggs of Toxocara sp. have been found in sandboxes in several public places in the city of Campo Grande, Mato Grosso do Sul state2. This study was carried out to detect the presence of anti-Toxocara antibodies in children attending the Pediatrics division of Hospital Universitário of Universidade Federal de Mato Grosso do Sul at Campo Grande, Brazil. Over the years 1992-94, 454 serum samples, obtained from children of 5.25 ± 3.28 years of mean age and selected at that hospital on the basis of eosinophil count greater than or equal to 1000/mm3 of blood, were tested for the presence of antibodies by means of the ELISA technique employing Toxocara canis larvae excretory-secretory antigens5. A high prevalence rate for toxocariasis (35.55%) was found, which was observed to be associated with eosinophil levels lower than those usually reported in literature. Furthermore, a higher frequency of positive serology among boys was also observed (13 cases in contrast to only 3 among girls), a result also reported by other authors

CHRONIC CHAGASIC CARDIOPATHY: THE PRODUCT OF A TURBULENT HOST-PARASITE RELATIONSHIP

The pathogenesis of chronic chagasic cardiopathy is still a debated matter. In this review, the main theories raised about it since the first description of the disease in 1909 by Carlos Chagas, are considered. The scarcity of T.cruzi parasites into the myocardium and the apparent lack of correlation between their presence and the occurrence of myocardial inflammatory infiltrate, have originated many theories indicating that chronic Chagas' cardiopathy is an autoimmune disease. Recently however, papers using immunohistochemical technique or PCR have demonstrated a strong association between moderate or severe myocarditis and presence of T.cruzi Ags, indicating a direct participation of the parasite in the genesis of chronic chagasic myocarditis. Different patterns of cytokine production seem to have important role in the outcome of the disease. Participation of the microcirculatory alterations and fibrosis as well as the relationship with the parasite are also emphasized. Finally, the author suggests that the indeterminate form of the disease occurs when the host immunological response against the parasite is more efficient while the chronic cardiopathy occurs in patients with hyperergic and inefficient immune response