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Inhibitory effects of plasma from uraemic patients on human mononuclear phagocytes cultured in vitro
Abstract:
Human mononuclear phagocytes were cultured in plasma from uraemic patients. The presence of uraemic plasma during the engulfment or digestion of 125I-labelled Candida albicans did not inhibit these functions in mononuclear phagocytes cultured for 8 days under normal condition. When normal human macrophages were cultured in the presence of uraemic plasma for 2-4 days, a marked detachment of the cells from the glass coverslips was registered. The phagocytic function of the remaining cells was impaired. Creatinine, urea and methylguanidine in concentrations higher than those usually measured in plasma from uraemic patients did not influence the functional properties of the cells. The inhibitory effect of uraemic plasma on the mononuclear phagocytes is suggested as an explanation for the increased frequency of infections in uraemic patients.
Insights
Uremic plasma impairs macrophage function, leading to cell detachment and reduced phagocytosis. This may explain the higher infection rates observed in patients with kidney failure.
Area of Science:
- Immunology
- Nephrology
- Cell Biology
Background:
- Patients with kidney failure (uremia) often experience increased susceptibility to infections.
- The precise mechanisms underlying this immune deficiency are not fully understood.
Purpose of the Study:
- To investigate the direct effects of uremic plasma on human mononuclear phagocyte function.
- To determine if specific uremic toxins contribute to impaired immune cell activity.
Main Methods:
- Human mononuclear phagocytes were cultured in plasma from uremic patients.
- Phagocytic activity and cell adherence were assessed using 125I-labelled Candida albicans.
- The impact of isolated uremic toxins (creatinine, urea, methylguanidine) was evaluated.
Main Results:
- Uremic plasma did not inhibit phagocytosis or digestion in macrophages cultured for 8 days.
- Short-term (2-4 days) exposure to uremic plasma caused significant macrophage detachment from surfaces.
- The phagocytic function of remaining macrophages was impaired following uremic plasma exposure.
- High concentrations of creatinine, urea, and methylguanidine did not replicate the inhibitory effects.
Conclusions:
- Uremic plasma, rather than specific toxins alone, adversely affects macrophage adherence and function.
- The observed impairment of mononuclear phagocytes by uremic plasma offers a potential explanation for increased infection risk in uremic patients.