Impaired production of gamma-interferon by newborn cells in vitro is due to a functionally immature macrophage

Area of Science:

• Immunology
• Neonatal Immunology
• Cellular Immunology

Background:

• Leukocytes from normal newborns exhibit decreased production of gamma-interferon (IFN) following phytohemagglutinin (PHA) stimulation.
• This diminished IFN production may stem from functional immaturity in T cells, macrophages, or both.

Purpose of the Study:

• To investigate the specific contributions of macrophages and T cells to impaired gamma-IFN production in neonatal leukocytes.
• To compare the gamma-IFN producing capacity of neonatal and adult immune cells in vitro.

Main Methods:

• Macrophages and T cells were isolated from 50 cord blood samples and 14 adult blood samples.
• Adherent macrophages were cultured for 7 days, followed by the addition of T cells.
• Supernatants from PHA-stimulated macrophage-T cell co-cultures were assayed for gamma-IFN using a microassay.

Main Results:

• Adult macrophage-T cell co-cultures showed significantly enhanced IFN production compared to Ficoll-Hypaque separated mononuclear cells.
• No IFN was detected in PHA-stimulated cord blood cell cultures, alone or in combination.
• Neonatal macrophages co-cultured with adult T cells produced minimal IFN, while neonatal T cells with adult macrophages showed enhanced IFN production.

Conclusions:

• The primary cause of impaired gamma-interferon response in newborns is a functional defect in neonatal macrophages.
• This macrophage dysfunction is not due to an inhibitory substance and can improve with in vitro cultivation.
• Understanding this neonatal macrophage defect is crucial for neonatal immune system development and function.