From the Guidelines
Elevated Natural Killer T (NKT) cells in flow cytometry are most commonly associated with conditions that trigger immune activation, such as viral infections, autoimmune disorders, and certain malignancies, particularly hematologic cancers like leukemias and lymphomas, as seen in Sézary syndrome 1. When considering the causes of elevated NKT cells, it's essential to look at the broader context of immune system dysregulation. Conditions like Sézary syndrome, a type of cutaneous T-cell lymphoma, demonstrate a progressive impairment of cellular immunity, which includes the functions of natural killer (NK) cells and their subsets like NKT cells 1. Key points to consider in the interpretation of elevated NKT cells include:
- Viral infections, which can lead to chronic immune activation and expansion of NKT cells
- Autoimmune disorders, where NKT cells may be elevated as part of the dysregulated immune response
- Hematologic malignancies, such as leukemias and lymphomas, which can directly or indirectly affect NKT cell populations
- Inflammatory conditions and genetic disorders affecting lymphocyte development, which may also lead to abnormal NKT cell levels Given the complexity and the variety of conditions that can lead to elevated NKT cells, the clinical context and other laboratory findings are crucial for accurate interpretation, as elevated NKT cells typically indicate ongoing immune activation or dysregulation 1.
From the Research
Elevated Natural Killer T (NKT) Cells in Flow Cytometry
Elevated NKT cells in flow cytometry can be caused by various factors, including:
- Immunophenotypic features of normal T and NK cells 2
- Technical issues in flow cytometry, such as approach to diagnosis and pitfalls in interpretation 2
- Presence of T and NK-cell lymphoproliferative disorders 2
- Activation of NK-cells through balance between inhibiting and activating receptors 3
- Cytotoxicity of NK-cells and production of cytokines, providing regulatory role of NK-cells as important participants of adaptive immune system 3
Role of NKT Cells in Immune Response
NKT cells play an essential role in the orchestration of the innate and adaptive immune responses against various diseases 4
- They recognize lipid antigens, unlike conventional T lymphocytes that recognize peptide antigens presented by class I or class II MHC 4
- Type I NKT cells can influence the differentiation of CD4+ T cells via cytokines in vitro, suggesting an important role in autoimmune diseases such as rheumatoid arthritis 5
Detection of NKT Cells by Flow Cytometry
Flow cytometry is an effective tool for detecting NKT cells, allowing immunophenotyping using fluorescently conjugated antibodies for the identification of subgroups of immune cells at a single-cell level 4, 6
- Multiparameter flow cytometer can be used to detect mouse NKT cells, including NKT follicular helper (NKT(FH)) cells 6