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[Opsonin requirements for phagocytosis of Enterococcus spp. by human polymorphonuclear leukocytes]
I García1, P Joyanes, A Pascual
1Departamento de Microbiología, Facultad de Medicina, Universidad de Sevilla.
Background:
Interaction of Enterococcus spp. and host defense mechanisms is not well known. Opsonic requirements of Enterococcus faecalis and Enterococcus faecium to be phagocyted by human polymorphonuclear leukocytes (PMN) were evaluated.
Methods:
Twenty strains (10 E. faecalis and 10 E. faecium) were studied. Phagocytosis was determined by a radiometric assay. Bacterial cells were labelled with 3H-adenine and opsonized with: a) 10% of human pool sera (HPS); b) 10% of decomplemented HPS, and c) albumin and fibronectin.
Results:
Phagocytosis of Enterococcus spp. by PMN in the presence of HPS was significantly higher than that in the absence of opsonins. The phagocytosis of E. faecium was higher than that of E. faecalis. A strain-dependent effect of complement in the phagocytosis of Enterococcus spp. was observed. Neither albumin nor fibronectin showed an opsonic activity on Enterococcus spp.
Conclusions:
A great heterogeneity in the opsonic requirements of Enterococcus spp. was observed. Serum opsonins show a critical role in the phagocytosis of E. faecalis and E. faecium by PMN, this effect being more relevant with E. faecium. A strain-dependent opsonic activity of complement was observed.
Insights
Serum opsonins are crucial for human immune cells to engulf Enterococcus bacteria, with Enterococcus faecium requiring more opsonization than Enterococcus faecalis. Complement
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- The interaction between Enterococcus species and host defense mechanisms is poorly understood.
- Opsonic requirements for phagocytosis of Enterococcus faecalis and Enterococcus faecium by human polymorphonuclear leukocytes (PMN) were investigated.
Purpose of the Study:
- To evaluate the opsonic requirements for phagocytosis of Enterococcus species by human PMN.
- To determine the role of serum opsonins, complement, albumin, and fibronectin in Enterococcus phagocytosis.
Main Methods:
- Studied twenty strains of Enterococcus (10 E. faecalis, 10 E. faecium).
- Quantified bacterial phagocytosis using a radiometric assay with 3H-adenine labeled bacteria.
- Opsonized bacteria with human pool sera (HPS), decomplemented HPS, albumin, and fibronectin.
Main Results:
- Phagocytosis of Enterococcus species by PMN was significantly enhanced by HPS compared to the absence of opsonins.
- Enterococcus faecium exhibited higher phagocytosis rates than Enterococcus faecalis.
- Complement demonstrated a strain-dependent effect on Enterococcus phagocytosis.
- Albumin and fibronectin did not exhibit opsonic activity against Enterococcus species.
Conclusions:
- Significant heterogeneity exists in the opsonic requirements of Enterococcus species.
- Serum opsonins play a critical role in PMN-mediated phagocytosis of E. faecalis and E. faecium, particularly for E. faecium.
- Complement exhibits strain-dependent opsonic activity against Enterococcus species.