The Effects Of Aspergillus Fumigatus On The Structure And Function Of Human Polymorphonuclear Neutrophils

Aspergillus fumigatus is a widespreadly existing fungus and it could cause severe opportunistic infection in patients with immune function suppression especially those with bone marrow transplantation or organ transplantation.The high risk factors for invasive Aspergillosis include malignant tumor, granulocytopenia, and glucocorticoid or immunodepressant utilization etc.Recently,the incidence of invasive Aspergillosis is on the rise and it has become one of the major death causes in patients with immune function suppression .In healthy people,the Aspergillus fumigatus could be excluded by PMN.PMN is one of the important component of human defence system and has close association with human non-specific anti-infection process.The PMN cells have very powerful ability to engulf and kill bacterium,which involves the identification and binding with the bacterium and then engulf them and kill them.However,the relationship between the Aspergillus fumigatus pores and the PMN is still elusive.In this study,we choose the PMN as the targeted cell and observe the effects of Aspergillus fumigatus pore and its metabolites on the morphology of PMN ,the O2- level produced by PMN respiratory bursting, phagocytosis rate and phagocytosis index etc in order to give some basic evidence on the reason why patients underwent organ transplantation are prone to contract Aspergillus fumigatus.We first used an improved method to isolate and purify the human PMN both from normal people and patients with liver transplantation and being verified by Giemsa ' s stain,the purity of the isolated PMN cells is over 98% ,also being verified by trypan blue staining ,the vitality of the isolated PMN cells is over 98%.Our experience indicate that this improved method can rapidly and simply yield abundant human PMN cells and has less effect on its vitality.We incubated the PMN with Aspergillus fumigatus pore and its metabolites and then used the PAS staining and electron microscopy to study the PMN's morphological change and its correlation with the engulfing function.Our results showed that the normal PMN has protuberance ,integrated mitochondria as well as pseudopod formation and the density of kytoplasm is well-distributed .After being stimulated by Aspergillus fumigatus,the surface of PMN increased greatly which could make one PMN binded more pores and in the process of internalization,the lysosome and endocytoplasmic reticulum also increased dramatically .The metabolites of Aspergillus fumigatus,ie,the AfD had some cytotoxic effects on the PMN which might play a key role in the Aspergillus fumigatus infection.The O2- production is the main pathway to kill the pathogens after PMN stimulation so detection of the O2- level by flow cytometry could indirectly reflect the PMN function.Our data showed that after being stimulated by Aspergillus fumigatus ,the O2- production from PMN taken from the liver transplantation patients were much lower than those of control group.The engulf rate and engulf index of PMN were significantly lower in liver transplantation patients than in normal control group after being stimulated by Aspergillus fumigatus pores and AfD verified by the PAS staining and electron microscopy.The engulf rate and engulf index of PMN were significantly lower after being stimulated by Aspergillus fumigatus and AfD mixture in comparision with being stimulate by Aspergillus fumigatus alone in liver transplantation group .Our study proved that liver transplantation patients who were easy to respond to Aspergillus fumigatus had close correlationship with the lowed respiratory bursting of PMN in them.Also we proved the relation between the morphology and function of PMN in both liver transplantation patients group and normal group .