In vitro and in situ activation of the complement system by the fungus Lacazia loboi

Since there are no studies evaluating the participation of the complement system (CS) in Jorge Lobo's disease and its activity on the fungus Lacazia loboi, we carried out the present investigation. Fungal cells with a viability index of 48 percent were obtained from the footpads of BALB/c mice and incubated with a pool of inactivated serum from patients with the mycosis or with sterile saline for 30 min at 37 °C. Next, the tubes were incubated for 2 h with a pool of noninactivated AB+ serum, inactivated serum, serum diluted in EGTA-MgCl2, and serum diluted in EDTA. The viability of L. loboi was evaluated and the fungal suspension was cytocentrifuged. The slides were submitted to immunofluorescence staining using human anti-C3 antibody. The results revealed that 98 percent of the fungi activated the CS by the alternative pathway and no significant difference in L. loboi viability was observed after CS activation. In parallel, frozen histological sections from 11 patients were analyzed regarding the presence of C3 and IgG by immunofluorescence staining. C3 and IgG deposits were observed in the fungal wall of 100 percent and 91 percent of the lesions evaluated, respectively. The results suggest that the CS and immunoglobulins may contribute to the defense mechanisms of the host against L. loboi.

Considerando que não existe nenhum estudo avaliando a participação do sistema complemento (SC) na doença de Jorge Lobo e sua atividade sobre o fungo Lacazia loboi, realizamos o presente trabalho. Os fungos foram obtidos dos coxins plantares de camundongos BALB/c com índice de viabilidade de 48 por cento e, em seguida, foram incubados com pool de soro inativado de pacientes ou com solução salina estéril (SSE) por 30 min, a 37 °C. Os tubos foram incubados, por 2 h, com pool de soro AB+ sem inativar, inativado, diluído em EGTA-MgCl2 e EDTA. A viabilidade do L. loboi foi avaliada e a suspensão fúngica foi citocentrifugada. As lâminas foram submetidas à técnica de imunofluorescência empregando o anticorpo anti-C3 humano. Os resultados revelaram que 98 por cento dos fungos ativaram o SC pela via alternativa e que não houve diferença significante na viabilidade do L. loboi após ativação do SC. Em paralelo, cortes histológicos congelados de 11 pacientes foram avaliados quanto à presença de C3 e IgG, pela técnica de imunofluorescência. Foram encontrados depósitos de C3 e de IgG na parede dos fungos em 100 por cento e 91 por cento das lesões avaliadas, respectivamente. Os resultados sugerem que o SC e as imunoglobulinas poderiam contribuir nos mecanismos de defesa do hospedeiro contra o L. loboi.

Vaccinia complement control protein: multi-functional protein and a potential wonder drug.

Vaccinia virus complement control protein (VCP) was one of the first viral molecules demonstrated to have a role in blocking complement and hence in the evasion of host defense. Structurally it is very similar to the human C4b-BP and the other members of complement control protein. Functionally it is most similar to the CR1 protein. VCP blocks both major pathways of complement activation. The crystal structure of VCP was determined a little over a year ago and it is the only known structure of an intact and complete complement control protein. In addition to binding complement, VCP also binds to heparin. These two binding abilities can take place simultaneously and contribute to its many function and to its potential use in several inflammatory diseases, e.g. Alzheimer's disease (AD), CNS injury, xenotransplantation, etc. making it a truly fascinating molecule and potential drug.

El sistema del complemento sérico: parte 1, mecanismos de reacción y efectos biológicos / The serum complement system: part1, activation mechanisms and biological effects

A un siglo de su descubrimiento por Bordet, se trata de poner un poco de orden en los mecanismos de activación del complemento a través de su hasta ahora conocidas rutas de activación clásica o de C1 y la vía alterna o de la properdina. Se hace además referencia a otras vías de activación descritas más recientemente como la activación iniciada por la lectina de unión a la manosa (MBL). Se destaca también la actividad de los componentes inhibidores o controladores, que frenan la actividad del sistema, evitando la producción de daños por la formación y liberación de péptidos con potente acción biológica derivados del mismo, tal el caso de las anafilatoxinas. Se hace además referencia a la presencia de receptores para el complemento, ubicados en la membrana de diversas células del sistema inmunológico, responsables de muchas de las principales actividades del sistema, como la fagocitosis de microorganismos a través de la unión de receptores para C3b (principal opsonina) sobre la membrana de las células fagocitarias

Importância do sistema do complemento em nefrologia / The importance of the complement system in nephrology

Neste artigo de revisäo, os autores ressaltam a importância do sistema do complemento na patogênese de certas formas de glomerulonefrites humanas pela ocorrência de hipocomplementemia, a possível correlaçäo entre hipocomplementemia e atividade de doença e a lesäo tecidual mediada por complemento em certos modelos experimentais comparáveis as doenças humanas. A atividade do sistema do complemento é comentada com relaçäo à sua dosagem sérica, urinária e pesquisa de imuno-complexos depositados no rim por imunofluorescência direta.

Flow cytometry evaluation of complement mediated bacterial membrane damage

The study of the complement-outer bacterial membrane interactions is gaining enthusiasm for applying a continous development of more specialized techniques. In this paper a novel flow cytometry technique shows that highly fluorescent lucifer yellow-stained Neisseriae gonorrhoeae when exposed to the redox reaction of p-nitro blue chloride tetrazolium (NBT), as formazan precipitation takes place, a shift to lesser fluorescent channels of the histogram population occurs. That effect is labeled NBT-laser beam quenching (NBT-LBQ). A significant difference by Kolmogorov-Smirnov summation curve analysis is found between complement heat-inactivated and its counterpart assessed with normal complement microorganisms. The operation of this NBT-LBQ effect by microbial flow cytometry casts an interesting potential for the evaluation of the outer membrane-complement-interaction of serum sensitive microorganisms

Effect of the complement system on the sensitivity of Campylobacter jejuni and Campylobacter coli to human blood serum

We determined the sensitivity of five strains Compylobacter jejuni and C. coli isolated from children with diarrhea and from chicken feces to normal human blood serum (undiluted and at concentrationss of 10, 30, 50 and 70 per cent), hypogmmaglobulinemic serum and a complemented-deficient serum. Both species were highly sensitive to the bactecidal activity of human serum, regardless of their source. The highest bactericidal activity was observed with pooled fresh normal serum, with bacterial survival rates inversely correlated to serum dilutions. Inactivated serum had the least bactericidal activity. When complement was partially restored to inactivated serum, lower survival rates were observed. The hypogammaglobulinemic-normal complement-containing serum had strong bactericidal activity whereas the normal immunoglobulin-containing but complement-feficient serum had little bactericidal activity. These results suggest that Campylobacter may be able to directly activate complement by the alternative pathway

El sistema de complemento. Mecanismos de activacion y regulacion / Complement system Mechanisms of activation and regulation

En el presente articulo se hace una revision sobre el tema del complemento, las propiedades y caracteristicas de los diferentes componentes, tanto humorales como celulares; los mecanismos de activacion y regulacion de esta, con la consecuente formacion de diversos productos con propiedades biologicas.

Valores normales de inmunoglobulinas y fracción C3 y C4 del complemento sérico en la población pediátrica chilena / Normal values of immunoglobulins and C3 and C4 fractions of the serum complement in chilean pediatric population

Se estudian 268 niños del area Metropolitana Occidente, con edades comprendidas entre 0 y 11 años. El trabajo tiene por finalidad determinar valores normales de referencia de inmunoglobulinas G, M y A y de las fracciones C3 y C4 del complemento sérico, utilizando el método de inmunodifusión radial de Mancini. Se comunican los resultados obtenidos

Requirements of Opsono-phagocytosis of staphylococci

Opsonophagocytosis of both Staph. aureus and coagulase negative staphylococci was studied in 46 strains from different sources of infection. Opsonophagocytosis was found to be mediated by the antibody and complement [in normal human serum] but could be also mediated by antibody alone in absence of the complement [in heated serum]. Also, it could be mediated by the complement alone in the absence of the antibody [in absorbed serum]. Coagulase negative staphylococci was more susceptible to opsonophagocytosis than Staph. aureus strains. No difference in opsonophagocytosis was found according to difference of sources of isolation

Phagocytic activity of human colostrum macrophages

1. We evaluated the ability of human colostrum adhering cells to phagocytize sheep red blood cells (E) incubated with rabbit anti-E IgG antibody (A) and zymosan particles incubated with fresh human serum or with the aqueous phase of colestrum. 2. The cells were found to have considerably intense phagocytuc ability, i.e., 96,8% phagocytized EA parcicles, 83.2% phagocytized zymosan particles opsonized with fresh human serum, and 73.3% phagocytized zymosan particles opsonized with the aqueous phase of colostrum. Thus, the aqueous phase of colostrum can opsonize zymosan particles, an activity attributed to the complement system. 3. Total hemolytic complement (V+CH50) and the C3 component in a pool of normal human serum were two-fold higher than in a pool of the aqueous phase of colostum. 4. These results indicate the existence of Fcgama and C3 receptors on the membrane of human colostum macrophages and suggest that these cells may be biologically active

Adherence of human eosinophils to infective filariform larvae of Necator americanus in vitro.

Eosinophilia is common in hookworm infection but the interaction between eosinophils and the larval stage of the parasite is poorly understood. The present study was conducted to test the ability of the eosinophils to adhere to infective filariform larvae of Necator americanus in vitro. Adherence of eosinophils to the larvae was found to be serum dependent. Antibody facilitated eosinophil adherence but this was maximal in the presence of complement. The adherence was greatly diminished by EGTA treated normal human serum (NHS) and was completely abolished when NHS was treated with either EDTA or heat-inactivation, suggesting that the process can be facilitated through complement activation via the alternative pathway. As with other nematodes, the surface of hookworm larvae appeared to be both antigenic and complement-activating. Although it is not known whether eosinophil adherence has any larvicidal effect, the present study demonstrated for the first time a definite interaction between human eosinophils and hookworm filariform larvae.

Papel del complemento en la recuperación funcional de los receptores para IgG bloqueador por complejos inmunes / Role of complement in the functional recovery of IgG receptors blocked by immune complexes

La interacción de complejos inmunes (CI) con receptores para el fragmento Fc de IgG (RFcgama) expresados en leucocitos pone en marcha mecanismos efectores y regulatorios de suma relevancia en el curso de la respuesta inmune. En trabajos anteriores, empleando la citotoxicidad celular dependiente de anticuerpos (ADCC) como expresión funcional de los RFcy, hemos demostrado que las células monocucleares periféricas humanas (CMPH), previamente bloqueadas en CI, recuperan la capacidad de mediar la ADCC a través de la activación de la vía alternativa del complemento (VAC). El objetivo de este trabajo fue analizar los mecanismos de recuperación funcional de los RFcgama cuando éstos han sido bloqueados por CI no fijadores de complemento (C). A tal fin, la IgG usada para preparar los CI se trató con carbodiimida (CDI), procedimiento que modifica su capacidad para fijar C, sin alterar mayormente su sitio de combinación con el antígeno, ni su habilidad para unirse a los RFcgama. Los resultados obtenidos demostraron que el C sólo es eficiente para revertir el bloqueo de la ADCC por CI, cuando éstos son capaces de fijar C