Genetic characterization of Toxoplasma gondii isolates from eared doves (Zenaida auriculata) in Brazil / Caracterização genética de isolados de Toxoplasma gondii de pombos (Zenaida auriculata) no Brasil

Eared doves (Zenaida auriculata), which are common in urban, rural and wild areas in many regions of Brazil, are frequently prey for domestic cats. Therefore Toxoplasma gondii isolates obtained from doves may reflect greater environmental diversity than those from other hosts. The aim of the present study was to evaluate T. gondii seroprevalence, isolate and genotype strains from Z. auriculata. Serum and tissue samples were collected from 206 doves for use in the modified agglutination test (MAT) and mouse bioassay. The prevalence of T. gondii antibodies in the doves was 22.3% (46/206), with titers ranging from 16 to 4096, and T. gondii strains were isolated from 12 of these doves. Five genotypes were detected by means of PCR-RFLP, including ToxoDB genotypes #1, #6, #17 and #65, and one genotype that had not previously been described (ToxoDB#182). This was the first report on isolation of T. gondii from Z. auriculata. This study confirmed the genetic diversity of T. gondii isolates and the existence of clonal type II (ToxoDB genotype #1) in Brazil.

Pombos silvestres (Zenaida auriculata), comuns em áreas urbanas, rurais e selvagens em muitas regiões do Brasil, são frequentemente predados por gatos domésticos. Sendo assim, os isolados de T. gondii obtidos de pombos podem refletir uma maior diversidade ambiental do que os outros hospedeiros. O objetivo do presente estudo foi avaliar a soroprevalência, isolar e genotipar T. gondii de Z. auriculata. Amostras de soro e tecido foram coletadas de 206 pombos para o teste de aglutinação modificado (MAT) e o bioensaio em camundongos. A prevalência de anticorpos contra T. gondii em pombos foi 22,3% (46/206), com títulos variando de 16 a 4096, e T. gondii foi isolado de 12 pombos. Cinco genótipos foram detectados por PCR-RFLP, incluindo os genótipos ToxoDB #1, #6, #17, #65 e um genótipo não descrito anteriormente (ToxoDB#182). Esse é o primeiro relato de isolamento de T. gondii de Z. auriculata. Este estudo também confirmou a diversidade dos isolados de T. gondii e a presença de tipo clonal II (ToxoDB #1) no Brasil.

Fatal Pulmonary-renal Syndrome Manifested with Immune Complex Crescentic Glomerulonephritis in a Patient with MPO-ANCA Seropositivity

Recent reports have indicated that a significant number of immune complex glomerulonephritis (GN) cases are associated with antineutrophilic cytoplasmic antibody (ANCA). However, most of the reported cases were associated with underlying primary glomerular diseases. When primary glomerular diseases were not found, immune deposits tended to be non-specific and the level of ANCA is usually borderline. We report here upon a case of life-threatening pulmonary-renal syndrome manifested simultaneously with immune complex GN and myeloperoxidase (MPO)-ANCA seropositivity. A 29- year-old man was admitted with pulmonary hemorrhage and rapidly progressing renal dysfunction. On admission, ANCA revealed perinuclear staining with a titer of 1:160. The MPO-ANCA level was 59 IU by ELISA. Other serologic markers including ANA, anti-DS-DNA and anti-GBM Ab were negative. Renal biopsy showed cellular crescents in eight of 18 glomeruli. Immunofluorescence staining showed strong granular deposits of C3, C1q, IgG and IgM in the capillary loop and the mesangium. Electron microscopy showed multifocal electron dense deposits scattered in the mesangium, paramesangium, and the subendothelial and subepithelial areas. The patient initially responded to steroid and cyclophosphamide. MPO-ANCA decreased to less than 10 IU. Twenty three days after hospital discharge, the patient was re-admitted urgently with fever, generalized papulonodular skin lesions, and a recurrence of massive pulmonary hemorrhage and renal dysfunction. He died from uncontrolled pulmonary hemorrhage and respiratory insufficiency. P-ANCA titer and MPO-ANCA level at the second admission were 1:320 and 82 U/ml respectively. Interestingly, relapse was shown to be triggered by varicella zoster infection.

Modulation of Fc and C3b receptor activity of mouse peritoneal macrophages elicited by preformed immune complexes.

A study was undertaken to reveal the role of Fc and C3b receptor of mouse peritoneal macrophages (MPM) in the uptake of radiolabelled immune complexes. Large latticed preformed complexes consisting of human serum albumin (HSA)-anti HSA at equivalence (IC-Eq) and with antibody excess (IC-Ab) were observed to be avidly taken up by resident macrophages unlike small size complexes with antigen excess (IC-Ag). Macrophages elicited by thioglycollate (Tg) showed higher IC-binding capacity while IC-elicited MPM showed reduction in the same when compared to the resident cells. However, complement coated complexes were significantly taken up by these IC-elicited macrophages. Uptake studies were further extended to determine the expression of Fc and C3b receptor activity in MPM when elicited with preformed IC. Tg-elicited MPM were observed to bind greater number of IgG-coated erythrocytes (E-IgG) than resident MPM whereas IC-elicited MPM bound E-IgG poorly. When Fc receptors were blocked by in vitro IC treatment, poor binding of complement coated E-IgG [E(IgG)C] was recorded in resident MPM. The present complement medicated rosetting data tends to show enhanced expression of C3b receptors on IC-elicited macrophages.

Biochemical studies on stimulation of mouse peritoneal macrophages by interaction with preformed immune complexes.

Mouse peritoneal macrophages (MPM) were observed to be stimulated by both in vivo and in vitro interactions with preformed HSA-anti HSA immune complexes (IC) having different antigen-antibody ratios. This was indicated by cellular alterations in morphology, increase in cellular protein and lysosomal enzyme contents and a marked fall in 5' nucleotidase level. Analysis of cellular proteins of IC-elicited cells by SDS-polyacrylamide gel electrophoresis showed accumulation of 80, 47, 33, 28, 18 and 14 kDa proteins. Insoluble immune complexes at equivalence (IC-Eq) was found to be more effective in the stimulation process as compared to the soluble antigen excess complexes (IC-Ag). These IC-elicited cells secreted lesser amounts of lysosomal hydrolases when explanted in culture medium as compared to resting cells, whereas in vitro stimulation of resident MPM with IC resulted in enhanced lysosomal hydrolase release. IC-induced lysosomal secretion was time and dose dependent and varied with the nature of the complexes. Complement coated immune complexes (IC-CC) induced maximum enzyme secretion followed by IC-Eq and IC-Ag.

Effects of preformed immune complexes on liver enzymes & their serum clearance in mice.

Two different performed HSA-anti-HSA immune aggregates, insoluble complex at equivalence (IC-E) and soluble complex with 5 times antigen excess (IC-S)-were administered iv in experimental mice to study their interaction with liver cells. Both complexes produced no appreciable change in the levels of liver enzymes like acid phosphatase, cathepsin D and gamma-glutamyl transferase. However, marked reduction in the level of liver pseduocholinesterase (as much as 93%) was recorded in the treated animals under identical conditions of administration of both the complexes. Hepatic uptake studies revealed that within 5 min, maximal sequestration of IC occurred within the liver (10 to 18%) and the blood (70 to 82%) when computed in terms of total injected radioactive IC. After 4 h, radioactivity dropped to 3 per cent in liver and 50-40 per cent in blood. The liver seemed to be incapable of scavenging all the serum complexes at a time. Significant consumption of serum complement occurred, when freshly prepared complexes were administered to the animals, but the reduced complement level showed a tendency to reach normalcy after 2 h. The soluble and equivalence zone IC failed to exhibit identifiable discrimination facets with respect to handling by liver. The complexes IC-E and IC-S also behaved in a similar manner.

Inmunocomplejos en la psoriasis / Immunocomplexes in psoriasis

Se estudió el suero de 80 enfermos con psoriasis, de diversas formas clínicas (60 en placas, 13 en gotas y 7 atropáticas). Para ello se aplicó la técnica de microconsumo de complemento, que permitió identificar a los inmunocomplejos que contenían IgG. Los resultados obtenidos demostraron un 56,25% de positividad estadísticamente significativa, poniendo en evidencia su participación en la patogenia de esta enfermedad. Los inmunocomplejos hallados, no guardan relación con la evolución clínica de la enfermedad

Interacción de los complejos inmunes y sus receptors leucocitarios: su regulación por el sistema complemento y la ciclofosfamida / Interaction of immune complexes and their leukocyte receptors: its regulation by the complement system and cyclophosphamide

Durante el desarrollo de esta línea de investigación se investigaron aspectos relacionados a la interacción entre complejos inmunes (CI) y receptores celulares para el gragmento Fc de IgG (RFc g). En primer término se demonstró que la vía alternativa del complemento es la principal responsable de la liberación de los Cl unidos a los RFc de células mononucleares periféricas humanas. Este mecanismo regulador fue estudiado a travées de la recuperción funcional de la citotoxicidad celular dependiente de anticuerpos (CCDA), reacción muy sensible a la inhibición por Cl. Los resultados sugieren, al menos en parte, que los niveles de Cl circulantes no necesariamente están relacionados en forma directa con el daño producido por los mismos. Por otro lado, se demonstró que la ciclofosfamida (Cy), droga de amplio uso en el tratamiento de enfermedades que cursan con Cl, es un eficiente amplificador de la depurción de Cl particulados, a través de la activación del sistema mononuclear fagocítico. Finalmente, se demonstró que los Cl son capaces de mediar efectos citotóxicos inespecíficos hacia diferentes células "blanco", a través de la inducción de la liberación de intermediarios reactivos del O2

Circulating Immune Complexes in Diabetics

Circulating immune complexes (ClC) were detected by platelet aggregation test (PAT) in 40.0% of 45 diabetics and by polyethylene glycol precipitation-complement consumption test (PEG-CC test) in 30.6% of 36 diabetics as compared to 5% and 10% of 20 normal control subjects for each test. The prevalence of CIC in diabetics was significantly higher than in the normal controls (P < 0.05%). There were no correlations between the presence of ClC detected by PAT and the duration of the disease, insulin treatment, or diabetic complications. Thus multiple factors must contribute to the increase of ClC in diabetics. The role of these various factors needs to be studied.