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Longitudinal development of specific and functional antibody in very low birth weight premature infants
K L Cates1, C Goetz, N Rosenberg
1Department of Pediatrics, University of Connecticut School of Medicine, Farmington.
Insights
Preterm infants show lower antibody levels against tetanus and diphtheria at nine months, but their functional antibody activity improves to levels comparable to term infants by this age.
Area of Science:
- Immunology
- Neonatal Medicine
- Pediatrics
Background:
- Preterm infants exhibit unique immunological challenges.
- Understanding antibody formation in this population is crucial for vaccine strategies.
Purpose of the Study:
- To assess specific and functional antibody formation in preterm infants.
- To compare antibody levels and opsonic activity in preterm versus term infants.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) for IgG antibodies against tetanus and diphtheria toxoids.
- Measurement of opsonic activity using radiolabeled bacteria, leukocytes, and complement.
- Comparison of preterm infants (born <1500g, <32 weeks) with term infants at various chronological ages.
Main Results:
- Preterm infants had lower IgG antibody levels for tetanus and diphtheria at nine months compared to term infants.
- IgG-mediated staphylococcal opsonic activity in preterm infants reached levels comparable to term infants by nine months.
- IgM-mediated E. coli opsonic activity was low at birth but increased with age, becoming comparable between preterm and term infants by nine months.
Conclusions:
- While specific antibody levels may remain lower, functional antibody activity develops in preterm infants.
- This suggests a potential for improved immune responses with age and vaccination in this vulnerable group.
Abstract:
We evaluated the formation of specific and functional antibody in preterm infants born weighing less than 1500 g (mean 1088 g) and less than 32 wk gestational age (mean 28.8 wk). Plasma IgG antibody against tetanus and diphtheria toxoids were measured by an enzyme-linked immunosorbent assay. Opsonic activity of heat-inactivated plasma was measured using radiolabeled bacteria, adult polymorphonuclear leukocytes and exogenous human complement. In the presence of complement, the strain of coagulase negative staphylococcus used was opsonized by IgG antibody, and the strain of Escherichia coli by IgM. Geometric mean plasma levels of tetanus and diphtheria IgG antibody fell from birth to 4 months chronological age, but rose significantly by 9 months (approximately 2 months after the third dose of diphtheria, tetanus, pertussis vaccine). However, at 9 months they remained lower than the respective geometric mean levels in 9-month-old term infants (tetanus: p less than 0.001; diphtheria: p = 0.02). The preterm infants' mean plasma IgG staphylococcal opsonic activity fell from birth to 2.5 months, but by 9 months was comparable to that of term infants of the same age. Mean IgM opsonic activity for E. coli was very low at birth in both preterm and term infants. It rose with chronological age, correlating with the rise in total IgM (r = 0.48, p less than 0.001) and by 9 months the mean preterm and term infants' levels of IgM opsonic activity for E. coli were comparable.(ABSTRACT TRUNCATED AT 250 WORDS)