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.
- Infectious Diseases
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Contributors AK coordinated the study, analysed the data and drafted the manuscript. PTH and SL developed the initial protocol. All authors helped with the recruitment of and/or blood sampling from participates, contributed to the manuscript review and revision and approved the final version.
Competing interests AJP has previously conducted studies on behalf of Oxford University funded by vaccine manufacturers but does not receive any personal payments or travel support. AJP chairs the UK Department of Health's (DH) Joint Committee on Vaccination and Immunisation (JCVI); the views expressed in this manuscript do not necessarily reflect the views of JCVI or DH. MDS acts as chief and principal investigators for clinical studies from both non-commercial funding bodies and commercial sponsors (ie, Novartis Vaccines, GlaxoSmithKline, Sanofi-Pasteur, Sanofi-Pasteur MSD and Pfizer Vaccines) conducted on behalf of the University of Oxford. MDS also undertakes consultancy and advisory work for several commercial sponsors; any speaking honoraria, travel and accommodation reimbursements are paid to the University of Oxford Department of Paediatrics. MDS does not receive any financial support from vaccine manufacturers. SNLand PTHhave conducted studies on behalf of St Georges, University of London, funded by vaccine manufacturers but does not receive any personal payments or travel support.
Funding This study was an investigator-initiated study funded by Pfizer.
Competing interests None declared.
Patient consent Obtained.
Ethics approval East of England—Essex regional ethics committee (REC reference 07/HO301.11).
Provenance and peer review Not commissioned; externally peer reviewed.