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Natural killer cell activity in infants and children excreting cytomegalovirus
Insights
Natural killer cell (NKC) activity increases with age in children. In infants with cytomegalovirus (CMV) and interstitial pneumonitis, NKC activity against infected cells is higher, while activity against uninfected cells is significantly elevated, indicating active disease.
Area of Science:
- Immunology
- Virology
- Pediatrics
Background:
- Natural killer cell (NKC) activity is crucial for innate immunity.
- Cytomegalovirus (CMV) infection is common in infants and can lead to serious complications.
- Understanding NKC responses in CMV infection is important for managing pediatric diseases.
Purpose of the Study:
- To investigate NKC activity in infants and children with and without CMV infection.
- To correlate NKC activity with the presence and severity of interstitial pneumonitis (IP) in CMV excreters.
- To assess NKC responses against CMV-infected and uninfected target cells.
Main Methods:
- NKC activity was measured in 39 CMV-excreting infants/children and 89 controls.
- Target cells included uninfected fibroblasts, CMV-infected fibroblasts, and K562 cells.
- NKC activity was assessed based on mean percentage lysis (MPL) and correlated with clinical data.
Main Results:
- NKC activity showed a significant age-dependent increase in cord blood, infants, and children.
- CMV excreters with interstitial pneumonitis (IP) exhibited higher NKC lysis of CMV-infected cells compared to controls and those without IP.
- Elevated NKC activity against uninfected fibroblasts was strongly associated with active IP in CMV excreters, regardless of age.
Conclusions:
- NKC activity plays a role in the immune response to CMV infection in children.
- Increased cytolysis of uninfected cells, alongside responses to infected cells, may serve as a biomarker for active disease.
- Age is a significant factor influencing NKC function in pediatric CMV infection.
Abstract:
Natural killer cell (NKC) activity against uninfected and cytomegalovirus (CMV)-infected fibroblasts and K562 cells was assessed in 39 infants and children excreting CMV and 89 controls. NKC activity in cord blood specimens, healthy donors up to six months old, and donors older than six months showed significant increases (P less than .02) with age. NKC activities of CMV excreters correlated with acute disease characterized by interstitial pneumonitis (IP) and showed differential responses to the three target cells. CMV excreters younger than six months with IP showed greater mean percentage lysis (MPL; 36.6% +/- 10.5%) of CMV-infected cells than did those without pneumonitis (25.9% +/- 10%) or controls (22.1% +/- 8.0%). Excreters older than six months with IP showed activities comparable to controls; NKC activities of excreters without IP were depressed. Significantly elevated activity against uninfected fibroblasts characterized patients with IP regardless of age (MPL, 30.2% +/- 7.3% vs. 4.2% +/- 2.0% for healthy controls and 6.3% +/- 5.4% for excreters without IP). Increased cytolysis of uninfected fibroblasts was therefore associated with more active disease.