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Alteration of T cells and natural killer cells during chickenpox in infancy
1Department of Pediatrics, Kawasaki Medical School, Kurashiki City, Japan.
Insights
Infants with chickenpox show a lower CD4/CD8 ratio and increased natural killer (NK) cells, potentially explaining their mild illness and reduced immune response. This suggests NK cell activity may be key to milder chickenpox outcomes in babies.
Area of Science:
- Immunology
- Pediatrics
- Virology
Background:
- Chickenpox (varicella) typically presents with mild morbidity in infancy.
- The underlying immunological mechanisms for this mild response in infants are not fully understood.
Purpose of the Study:
- To investigate the alterations in T cells and natural killer (NK) cells during chickenpox in infants (< 1 year) compared to older children (≥ 2 years).
- To elucidate the relationship between immune cell changes and the clinical presentation of chickenpox in infancy.
Main Methods:
- Flow cytometry was used to analyze T cell subsets (CD4/CD8 ratio) and NK cell subsets (CD3-CD16+CD56+, CD57-CD16+) in children during acute and convalescent phases of chickenpox.
- Comparison of immune cell profiles between infants (< 1 year) and older children (≥ 2 years).
Main Results:
- The CD4/CD8 ratio decreased significantly in infants from the acute to convalescent phase.
- Counts of specific NK cell subsets (CD3-CD16+CD56+ and CD57-CD16+) increased in infants but not in older children.
- Infants exhibited higher counts and percentages of these NK cell subsets during the convalescent phase compared to older children.
Conclusions:
- The reduced CD4/CD8 ratio in infants may be linked to a lower number of CD8+ T cells relative to CD4+ T cells.
- Increased subsets of NK cells during chickenpox in infancy appear to correlate with the observed mild morbidity.
- These findings suggest a distinct immunological response to varicella-zoster virus in infants, characterized by specific T and NK cell dynamics.
Abstract:
To determine the reasons for the low immune response and the mild morbidity of chickenpox in infancy, we investigated alteration of T cells and natural killer (NK) cells during chickenpox in children < 1 year and > or = 2 years old using flow cytometry. The CD4/CD8 ratio decreased only in the < 1-year-old group from the acute to the convalescent phase (P < 0.05). The CD3-CD16+CD56+ and CD57-CD16+ counts increased in the < 1-year-old group, but those in the > or = 2-year-old group did not increase from the acute to the convalescent phase. The CD3-CD16+CD56+ counts and the CD57-CD16+ counts and percentage were larger in the < 1-year-old group than those in the > or = 2-year-old group (P = 0.001, P = 0.002, and P < 0.05) in the convalescent phase. These results seem to indicate that the low immune response in infancy after chickenpox are related to the small number of CD8 in contrast with CD4 and that increased subsets of NK cells during chickenpox may correlate to the mild morbidity of chickenpox in infancy.