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Neonatal invariant Valpha24+ NKT lymphocytes are activated memory cells
A D'Andrea1, D Goux, C De Lalla
1IRIS Research Center, Chiron, Siena, Italy.
European Journal of Immunology
|July 18, 2000
Summary
Newborn NKT cells, or natural killer T cells, possess an activated memory phenotype but are polyclonal and do not produce cytokines. They require further priming to function as innate immunity cells.
Area of Science:
- Immunology
- Innate Immunity
- T cell subsets
Background:
- Natural Killer T (NKT) cells are a distinct T lymphocyte subset recognizing glycolipids via CD1d.
- Adult NKT cells exhibit a memory phenotype, oligoclonal expansion, NK cell markers, and cytokine production upon stimulation, classifying them as innate immunity lymphocytes.
Purpose of the Study:
- To investigate the characteristics of NKT cells in human cord blood, representing their state before exogenous stimuli.
- To compare neonatal NKT cells with their adult counterparts.
Main Methods:
- Analysis of NKT cell frequency and phenotype (CD45RO, CD62L, CD25) in cord blood versus adult peripheral blood mononuclear cells.
- Assessment of NKT cell cytokine production upon primary stimulation.
- Evaluation of NKT cell clonality (polyclonal vs. oligoclonal).
Main Results:
- NKT cells are found at comparable frequencies in cord blood and adult peripheral blood.
- Both neonatal and adult NKT cells share a memory phenotype (CD45RO+CD62L-).
- Neonatal NKT cells differ by expressing activation markers (CD25), being polyclonal, and lacking primary cytokine production.
Conclusions:
- Human NKT cells emerge in newborns with an activated memory phenotype, likely from endogenous ligand recognition.
- Despite their activated memory phenotype, neonatal NKT cells are polyclonal and lack primary effector functions.
- Neonatal NKT cells require additional priming or differentiation to achieve full innate immunity cell functionality.