Bacillus Calmette-Guérin vaccination, thymic size, and thymic output in healthy newborns.
BACKGROUND
The Bacillus Calmette-Guérin vaccine (BCG) has been associated with beneficial nonspecific effects on infant health. We aimed to examine the effect of BCG at birth on thymic size and the associations between thymic output, circulating lymphocytes, risk of infection, and thymic size.


METHODS
In infants randomized to BCG or no BCG, thymic index (TI), and thymic/weight index (TWI) were measured by ultrasound at birth and at the age of 3 mo. T cell subpopulations including CD4+T cells, CD8+T cells, and recent thymic emigrants (RTEs) were assessed by flow cytometry. Infections up to age 3 mo were parent-reported.


RESULTS
BCG vaccination did not affect thymic size at age 3 mo, measured as TI. At birth, the number of lymphocytes, CD4+ T cells, CD8+ T cells, and RTEs were positively associated with TI and TWI. Furthermore, a reduced risk of infections up to age 3 mo was associated with a large thymic size at birth.


CONCLUSIONS
We found no effect of BCG vaccination on thymic size. The positive association between thymic output, lymphocytes, reduced risk of infections, and TI/TWI suggests that assessment of TI/TWI by ultrasound may be a predictor of the immunological capacity in the newborn.
Department of Pediatrics, Copenhagen University Hospital, Hvidovre, Denmark.
Nina Marie
NM
Birk
Department of Pediatrics, Copenhagen University Hospital, Hvidovre, Denmark.
Thomas Nørrelykke
TN
Nissen
Department of Pediatrics, Copenhagen University Hospital, Hvidovre, Denmark.
Vera
V
Zingmark
The Department of Pediatrics and Adolescent Medicine, Juliane Marie Centret, Rigshospitalet, Copenhagen University Hospital, Denmark.
Jesper
J
Kjærgaard
Department of Pediatrics, Kolding Hospital, Denmark.
Lisbeth Marianne
LM
Thøstesen
Department of Pediatrics, Kolding Hospital, Denmark.
Poul-Erik
PE
Kofoed
The Department of Pediatrics and Adolescent Medicine, Juliane Marie Centret, Rigshospitalet, Copenhagen University Hospital, Denmark.
Lone Graff
LG
Stensballe
Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, Copenhagen, Denmark.
Andreas
A
Andersen
Department of infectious diseases, Rigshospitalet, Copenhagen University Hospital, Denmark.
Susanne Dam
SD
Nielsen
Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, Copenhagen, Denmark.
Christine Stabell
CS
Benn
Department of Pediatrics, Copenhagen University Hospital, Hvidovre, Denmark.
Ole
O
Pryds
Department of Pediatrics, Copenhagen University Hospital, Hvidovre, Denmark.
Dorthe Lisbeth
DL
Jeppesen
D016175:B-Lymphocyte Subsets; D001500:BCG Vaccine / Q000008:administration & dosage*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D016176:T-Lymphocyte Subsets; D013950:Thymus Gland / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology
D001500:BCG Vaccine