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Synthesis and surface expression of ICAM-1 in polymorphonuclear neutrophilic leukocytes in normal subjects and during
Abstract:
During bacterial peritonitis of patients on continuous ambulatory peritoneal dialysis (CAPD) leukocytes, particularly polymorphonuclear neutrophilic granulocytes (PMNs), migrate into the peritoneal cavity. However, at the site of inflammation PMNs are not sufficiently able to protect the host against micro-organisms. Adhesion molecules, such as ICAM-1 (CD54), are involved in the interaction between endothelial cells and PMNs leading to the accumulation of PMNs at the site of inflammation. As PMNs are the predominant cell type in the peritoneal cavity in peritonitis, the aim of this study was to find out whether PMNs from CAPD peritonitis patients were able to express ICAM-1. Flow cytometric analyses with the anti-CD54 monoclonal antibody demonstrated that normal PMNs constitutively express slight amounts of ICAM-1. In contrast to normal PMNs, peritoneal PMNs from patients with CAPD peritonitis expressed high amounts of ICAM-1 (p = 0.003). Furthermore, ICAM-1 expression on peripheral blood PMNs of these patients significantly differed from PMNs from healthy donor (p = 0.01). Furthermore, Northern blot analysis revealed a weak signal of ICAM-1 mRNA in normal PMNs. However, peritoneal PMNs from CAPD peritonitis patients expressed a strong signal for ICAM-1 mRNA, suggesting that ICAM-1 is newly synthesized when PMNs invade the peritoneal cavity. In summary, this study clearly demonstrates that peritoneal PMNs of CAPD peritonitis express high amounts of ICAM-1 receptor on the level of mRNA and on the surface. Therefore, it is tempting to speculate that peritoneal PMNs interact amongst each other between ICAM-1 and its counter receptors CD11a,b/CD18 receptor.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Polymorphonuclear neutrophils (PMNs) in patients with continuous ambulatory peritoneal dialysis (CAPD) peritonitis show increased expression of Intercellular Adhesion Molecule-1 (ICAM-1). This suggests ICAM-1 plays a role in PMN accumulation during CAPD-related infections.
Area of Science:
- Immunology
- Nephrology
- Cell Biology
Background:
- Bacterial peritonitis in continuous ambulatory peritoneal dialysis (CAPD) patients involves leukocyte migration, particularly polymorphonuclear neutrophils (PMNs), into the peritoneal cavity.
- PMNs are crucial for host defense but may be functionally impaired at inflammatory sites.
- Adhesion molecules like ICAM-1 (CD54) mediate endothelial cell-PMN interactions, influencing PMN accumulation.
Purpose of the Study:
- To investigate whether PMNs from CAPD peritonitis patients express ICAM-1.
- To determine if ICAM-1 expression differs between peritoneal PMNs and peripheral blood PMNs in CAPD peritonitis patients compared to healthy controls.
Main Methods:
- Flow cytometry using anti-CD54 monoclonal antibody to analyze ICAM-1 surface expression on PMNs.
- Northern blot analysis to assess ICAM-1 messenger RNA (mRNA) levels in PMNs.
Main Results:
- Normal PMNs constitutively express low levels of ICAM-1.
- Peritoneal PMNs from CAPD peritonitis patients exhibit significantly higher ICAM-1 surface expression compared to normal PMNs (p = 0.003).
- Peripheral blood PMNs from CAPD peritonitis patients also show significantly increased ICAM-1 expression compared to healthy donors (p = 0.01).
- Northern blot analysis reveals a strong ICAM-1 mRNA signal in peritoneal PMNs from CAPD peritonitis patients, indicating de novo synthesis.
Conclusions:
- Peritoneal PMNs in CAPD peritonitis patients express high levels of ICAM-1 at both the mRNA and surface protein levels.
- The increased ICAM-1 expression suggests it is newly synthesized upon PMN invasion into the peritoneal cavity.
- This heightened ICAM-1 expression may facilitate PMN-PMN interactions via ICAM-1 and its counter-receptors (CD11a,b/CD18).