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Deficient tumor necrosis factor secretion by cord blood mononuclear cells upon in vitro stimulation with Listeria
B Serushago1, A C Issekutz, S H Lee
1Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada.
Abstract:
We examined the production of tumor necrosis factor (TNF) by mononuclear cells (MNC) after incubating adult or cord blood MNC with Listeria monocytogenes in vitro. With adult MNC cultures, we found that TNF activity reached a peak at 6 h (606 +/- 120 x 10(3) units/liter) and declined to the baseline by day 3. In contrast, using cord blood MNC, we found that TNF activity increased gradually reaching a peak at 24 h. In addition, the peak TNF activity using newborn MNC (189 +/- 26 x 10(3) U/liter) at 24 h was still lower than the peak using adult MNC at 6 h (p < 0.0002). In seeking an explanation for the decreased TNF secretion from newborn MNC, we examined the possibility that newborn cells produce TNF but failed to secrete it. However, lysates of newborn cells contained functionally and antigenically less TNF than adult cells. Based on these observations, we conclude that the overall TNF production by newborn cells incubated with L monocytogenes is decreased compared with similarly stimulated adult cells.
Insights
Newborns exhibit reduced tumor necrosis factor (TNF) production compared to adults when their mononuclear cells (MNC) are exposed to Listeria monocytogenes. This diminished TNF response in infants suggests a potential vulnerability to infections.
Area of Science:
- Immunology
- Cellular Biology
- Infectious Disease
Background:
- Tumor necrosis factor (TNF) is a crucial cytokine in the immune response.
- Mononuclear cells (MNC) are key players in innate and adaptive immunity.
- Understanding neonatal immune responses is vital for infant health.
Purpose of the Study:
- To compare TNF production by adult and cord blood MNC stimulated with Listeria monocytogenes.
- To investigate the kinetics and magnitude of TNF secretion in neonatal versus adult immune cells.
Main Methods:
- In vitro incubation of adult and cord blood MNC with Listeria monocytogenes.
- Measurement of TNF activity over time in cell cultures and lysates.
- Statistical analysis to compare TNF levels between adult and newborn groups.
Main Results:
- Adult MNC showed a rapid peak in TNF activity at 6 hours.
- Cord blood MNC exhibited a delayed peak in TNF activity at 24 hours.
- Peak TNF activity in newborn MNC was significantly lower than in adult MNC.
Conclusions:
- Neonatal MNC demonstrate a quantitatively reduced TNF production in response to Listeria monocytogenes compared to adult MNC.
- The decreased TNF levels are due to reduced production, not impaired secretion, by newborn cells.
- These findings highlight potential differences in neonatal immune defense mechanisms.