Identification and Isolation of Type II NKT Cell Subsets in Human Blood and Liver

Area of Science:

• Immunology
• Transplantation Immunology
• Cell Biology

Background:

• Steatotic livers, prone to rejection, are frequently transplanted due to organ scarcity.
• The role of Type II NKT (T2NKT) cells in fatty liver transplant rejection remains unclear due to low frequency and lack of markers.
• Liver-resident T2NKT cells are lymphocytes that respond to CD1d-presented lipids.

Purpose of the Study:

• To quantify human T2NKT cells in blood and liver tissue.
• To develop strategies for T2NKT cell enrichment and expansion.
• To investigate the characteristics of T2NKT cells, including potential novel subsets.

Main Methods:

• Human T2NKT cells identified as CD3+ CD56+ CD161+ TCR-γδ− TCRVα7.2− TCRVα24−.
• Enrichment of T2NKT cells from blood via CD56 and CD3 microbead selection.
• FACS-sorting for purity, followed by 3-week *in vitro* expansion with anti-CD3/CD28 beads and TGF-β1.

Main Results:

• T2NKT cells were rare in blood (0.8%) but more abundant in liver (6.3%).
• Enriched T2NKT cells expressed the transcription factor PLZF.
• A novel FoxP3+ T2NKT cell subset was identified in both blood and liver tissue.

Conclusions:

• New strategies for identifying and isolating human T2NKT cells from blood and liver were established.
• Rare T2NKT cells can be expanded *in vitro* to achieve experimentally useful numbers.
• A novel, stable FoxP3+ T2NKT subset may regulate innate-like lymphocyte responses in steatotic liver transplants.