Factors influencing phagocytosis of Salmonella typhimurium by macrophages in murine schistosomiasis

Abstract

We investigated the influence of Salmonella typhimurium load and specific antibodies on phagocytosis in schistosomiasis. Macrophages from Schistosoma mansoni-infected mice showed depressed capacity to increase the phagocytosis in the presence of a high bacterial load, due to a reduced involvement of these cells in phagocytosis and to a deficient ability to increase the number of phagocytosed bacteria. Normal and Salmonella-infected mice increased their phagocytic capacity when exposed to a high bacterial load. Antibody to Salmonella increased the phagocytic capacity of macrophages from Schistosoma-infected mice due to an increase in the number of bacteria phagocytosed but caused no modification in the number of macrophages engaged in phagocytosis. Our data indicate that macrophages from Schistosoma-infected mice work close to their functional limit, since no increase in phagocytosis was observed after increasing the bacterial load. Specific antibodies can improve their phagocytic capacity and, therefore, could help clearing concurrent infection.

Effect of piplartine and cinnamides on Leishmania amazonensis , Plasmodium falciparum and on peritoneal cells of Swiss mice

“…Then, a suspension containing 2 × 10 5 cells/well (>99% macrophages) (Muniz-Junqueira et al. 1997 ) was distributed in triplicate in 96 wells plate, in the presence of different concentrations (0 to 256 μg/mL) of amides ( 1 – 5 ) and incubated for 2 h at 37 °C with 5% of CO 2 in air; RPMI 1640 medium without cells was used as control. After that, 10 μL of a MTT solution (5 mg/mL) to all wells were added and, the plate was re-incubated protected from light for 4 h. The formazan crystals were solubilized with 50 μL of DMSO/well and the absorbance obtained in spectrophotometer (Spectra Max® Plus 384) with 550 nm.…”

Stages of in vitro phagocytosis of Plasmodium falciparum-infected erythrocytes by human monocytes

“…Cell viability was assessed using 0.05% nigrosin solution in 0.15M phosphate-buffered saline (PBS), pH 7.2, and was found to be always higher than 97%. The test of phagocytosis of erythrocytes infected with Plasmodium falciparum was adapted from a technique previously described 6 . Briefly, monocytes from individual volunteers were separated by adherence to 13-mm-diameter round glass coverslips in 24-well plastic plates (Flow, MacLean, USA) after incubation in a wet chamber for 2h at 37°C, in the presence of 5% CO 2 in air.…”

Salmonelose septicêmica prolongada associada à esquistossomose: evolução do conhecimento e mecanismos imunopatogênicos

“…Entretanto, em casos de salmonelose septicêmica prolongada, nos quais a Salmonella typhi havia sido identificada por hemocultura, não se detectou a produção de anticorpos específicos para os antígenos O e H da bactéria 90 80 encontraram em pacientes esquistossomóticos uma maior frequência de anticorpos para o antígeno O da Salmonella typhi, enquanto a frequência para antígenos H foi semelhante à observada em indivíduos normais. Entretanto, os indivíduos com a forma hepatoesplênica da doença mostraram títulos de anticorpos mais elevados para o antígeno H da bactéria do que os indivíduos com a forma intestinal e os não infectados.…”

“…Pode ser observado que os animais previamente infectados com a salmonela fagocitam intensamente a bactéria (Figura 3). Os macrófagos dos animais coinfectados por salmonela e esquistossoma mostraram uma menor reserva na capacidade fagocitária, pois foram incapazes de aumentar a fagocitose pelo aumento da carga bacteriana, sugerindo que os macrófagos dos animais esquistossomóticos já se encontram em seu limite funcional de atividade 80 , além de serem incapazes de destruir a bactéria após a fagocitose 79 , o que pode facilitar o desenvolvimento da forma crônica da salmonelose pela incapacidade de contenção do microorganismo.…”