The effect of conglutinin on production of reactive oxygen species in bovine granulocytes

Conglutinin is a high molecular-weight lectin originally detected in bovine serum. It belongs to the family of collectins that bind sugar residues in a Ca(2+)-dependent manner and are effector molecules in innate immunity. Conglutinin appears to play an important role in immune defense mechanisms, showing antiviral and antibacterial activities when tested in vivo and in vitro. The present study evaluated the effect of conglutinin on the respiratory bursts in bovine peripheral phagocytes. Using nitroblue tetrazolium and hydrogen peroxide assays, we showed that sugar ligand-bound conglutinin stimulated the production of superoxide and H2O2 in granulocytes whereas the non-sugar-bound form of conglutinin inhibited these processes. These results indicate that both forms of conglutinin are able to interact with surface leukocyte receptors but have opposite effects on phagocytic activity. Our findings suggest that conglutinin bound to sugar residues on microbial surfaces can induce oxygen burst in phagocytes, and thereby mediates the elimination of pathogens and prevents the spread of infection.

A 27 kDa Cysteine Protease Secreted by Newly Excysted Paragonimus westermani Metacercariae Induces Superoxide Anion Production and Degranulation of Human Eosinophils

Eosinophil degranulation plays a crucial role in tissue inflammatory reactions associated with helminth parasitic nfections and allergic diseases. Paragonimus westermani, a lung fluke causing human paragonimiasis, secretes a large amount of cysteine proteases, which are involved in nutrient uptake, tissue invasion, and modulation of hos's immune responses. There is, however, limited information about the response of eosinophils to direct stimulation by cysteine proteases (CP) secreted by P. westermani. In the present study, we tested whether degranulation and superoxide production from human eosinophils can be induced by stimulation of the 2 CP (27 kDa and 28 kDa) purified from excretory-secretory products (ESP) of P. westermani newly excysted metacercariae (PwNEM). A large quantity of eosinophil-derived neurotoxin (EDN) was detected in the culture supernatant when human eosinophils isolated from the peripheral blood were incubated with the purified 27 kDa CP. Furthermore, the 27 kDa CP induced superoxide anion production by eosinophils in time- and dose-dependent manners. In contrast, the purified 28 kDa CP did not induce superoxide production and degranulation. These findings suggest that the 27 kDa CP secreted by PwNEM induces superoxide production and degranulation of human eosinophils, which may be involved in eosinophil-mediated tissue inflammatory responses during the larval migration in human paragonimiasis.

Avaliação do efeito da esplenectomia e auto-implante esplênico sobre algumas funções de monócitos em crianças com esquistossomose mansônica / Evaluation of the effect of splenectomy with autologous spleen tissue implantation in some monocyte functions in children with hepatosplenic schistosomiasis mansoni

Investigamos em portadores de esquistossomose hepatoesplênica após esplenectomia com ou sem auto-implante esplênico: índice de aderência, produção de superóxido (SP) e de TNF-alfa em monócitos, tratados ou não com tuftsina. Avaliamos três grupos: voluntários sadios CG (grupo controle) (n=12); esplenectomizados com auto-implante AG (n=18) e esplenectomizados sem auto-implante WAG (n=9). índice de aderência e TNF-alfa não diferiram entre os grupos. SP foi semelhante em CG e AG na 1ª hora após estimulação celular. SP foi maior em todos intervalos de tempo nos grupos CG e AG, comparados ao WAG. O tratamento com tuftsina recuperou o padrão de normalidade de SP em AG, com aumento da 1ª para a 2ª hora nos níveis do CG. O tratamento com tuftsina não alterou SP em WAG, permanecendo reduzida em todos intervalos. O auto-implante esplênico parece recuperar e manter os parâmetros imunológicos avaliados, que têm participação importante na resposta do hospedeiro às infecções.