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Lymphocyte subpopulations in premature infants: an observational study
  1. Alison Kent1,
  2. Tim Scorrer2,
  3. Andrew J Pollard3,
  4. Matthew D Snape3,
  5. Paul Clarke4,
  6. Karen Few4,
  7. Esse Menson5,
  8. Anu S Varghese6,
  9. Stephen Hughes6,
  10. Shamez N Ladhani1,7,
  11. Paul T Heath1
  1. 1Paediatric Infectious Diseases Research Group and Vaccine Institute, St George's, University of London, London, UK
  2. 2Neonatal Unit, Queen Alexandra Hospital, Portsmouth, UK
  3. 3Oxford Vaccine Group, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, UK
  4. 4Neonatal Unit, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
  5. 5Department of Paediatric Infectious Diseases, Evelina London Children's Hospital, London, UK
  6. 6Department of Paediatric Allergy and Immunology, Royal Manchester Children's Hospital, Manchester, UK
  7. 7Immunisation, Hepatitis and Blood Safety Department, Public Health England, Colindale, London, UK
  1. Correspondence to Dr Alison Kent, Paediatric Infectious Diseases Research Group and Vaccine Institute, St George's, University of London, Cranmer Terrace, London SW17 0RE, UK; alisonkent{at}


Background and objectives The infant's immune system evolves over the first months and years of life. Strong correlation exists between lymphocyte count, lymphocyte subpopulations and gestational age at birth. Associations with antenatal and postnatal steroid treatment, infection and chronic lung disease have also been described. Few published studies report the effect of increasing postnatal age (PNA) and comorbidities on lymphocyte subpopulations in premature infants beyond the first 4 months of life. This study aimed to describe changes in lymphocyte subpopulations in preterm infants up to 13 months PNA.

Methods Premature infants (23–34 weeks completed gestation) from five centres had lymphocyte subpopulations measured at 2, 5 or 7, 12 and 13 months PNA alongside their vaccine responses in a vaccination trial.

Results 393 blood samples from 151 babies were analysed. There was an increase in absolute numbers of total lymphocytes (median cell count 6.21×109/L at 13 months compared with 4.9×109/L at 2 months PNA) and CD3+, CD4+, CD8+, natural killer and B cells with increasing age. At 2 months PNA, there was a positive correlation between gestation and CD3+ and CD4+ counts (r=0.32 and 0.46, respectively) and proportions (r=0.22 and 0.41, respectively), and CD4+:CD8+ ratios (r=0.57), but a negative correlation with CD8+ proportions (r=−0.32).

Conclusions This longitudinal study describes the distribution of lymphocyte subpopulations in premature infants and provides reference ranges for the major lymphocyte subsets to help guide clinicians when assessing premature infants for immunodeficiency in the first year of life.

Trial registration number EudraCT 2007-007535-23.

  • Neonatology
  • Immunology
  • Infectious Diseases

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