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Serum thymic hormone activity and cell-mediated immunity in healthy neonates, preterm infants, and
Insights
Immune function is impaired in low birth weight infants, particularly small-for-gestational age (SGA) newborns. Reduced thymic hormone activity and T cell counts may increase their susceptibility to infections.
Area of Science:
- Immunology
- Neonatal Medicine
- Pediatrics
Background:
- Low birth weight infants, including small-for-gestational age (SGA) and preterm appropriate-for-gestational age (AGA) infants, represent a vulnerable population.
- Understanding the development of cell-mediated immunity in these infants is crucial for assessing their health outcomes and infection risk.
Purpose of the Study:
- To investigate the development of cell-mediated immunity in healthy SGA and preterm AGA infants.
- To evaluate the role of thymic hormone (TH) activity and T lymphocyte parameters in low birth weight infants.
Main Methods:
- Longitudinal study of healthy SGA and preterm AGA infants from birth to 12 months.
- Assay of serum thymic hormone (TH) activity.
- Quantification of peripheral blood T lymphocytes.
- Evaluation of in vitro lymphocyte stimulation responses to phytohemagglutinin (PHA).
Main Results:
- Decreased TH activity observed in 1-month-old SGA infants.
- Reduced T cell counts noted in all low birth weight infants, normalizing by 3 months in preterm AGA infants but remaining low in SGA infants up to 12 months.
- Impaired lymphocyte stimulation responses correlated with reduced T cell numbers in low birth weight infants.
Conclusions:
- Cell-mediated immunity is impaired in low birth weight newborns.
- Reduced TH activity is a potential pathogenetic factor in immune dysfunction.
- Persistent immune deficiency in SGA infants may contribute to increased susceptibility to infections.
Abstract:
Groups of healthy, small-for-gestational age (SGA) and preterm appropriate-for-gestational age (AGA) infants were studied at birth, 1 month, 3 months, and 12 months of age. Serum thymic hormone (TH) activity was assayed, the number of T lymphocytes in the peripheral blood was counted, and in vitro lymphocyte stimulation responses to phytohemagglutinin (PHA) were evaluated. TH activity was decreased in 1-month-old SGA infants. T cells were reduced in all low birth weight infants; the number reverted to normal by 3 months of age in preterm AGA infants, whereas it remained low for at least 12 months in the SGA group. Lymphocyte stimulation response was decreased in low birth weight infants; the extent of depression paralleled reduction in T lymphocyte number. These observations indicate that cell-mediated immunity is impaired in low birth weight newborns and reduced TH activity may be one of the pathogenetic factors involved. Persistent depression of immunocompetence may underlie the increased susceptibility of SGA infants to infection-related morbidity and mortality.