Functional Differences between Human NKp44(-) and NKp44(+) RORC(+) Innate Lymphoid Cells.

Area of Science:

• Immunology
• Cell Biology

Background:

• Innate lymphoid cells (ILCs) are crucial for immune responses and tissue remodeling.
• Understanding human RORC(+) ILC subsets and their distribution is vital for assessing their role in health and disease.

Purpose of the Study:

• To characterize distinct subsets of human RORC(+) ILCs.
• To investigate the distribution and cytokine production profiles of these subsets in adults.

Main Methods:

• Flow cytometry to identify and distinguish ILC subsets based on NKp44 expression.
• Analysis of cytokine production (IL-17a, IL-22) by different ILC subsets.
• Examination of ILC distribution in fetal and adult human tissues (tonsils, lymph nodes, intestine).

Main Results:

• Two functionally distinct human RORC(+) ILC subsets were identified, secreting either IL-17a or IL-22.
• NKp44(+) ILCs primarily produce IL-22 and are found in adult intestines and tonsils.
• NKp44(-) ILCs, producing IL-17a, are found in fetal lymph nodes and can reside as resting cells in adult lymph nodes, capable of rapid cytokine production upon stimulation.

Conclusions:

• Human RORC(+) ILCs comprise distinct subsets with specific cytokine profiles and tissue distribution.
• NKp44(+) ILCs are key IL-22 producers in the adult intestine.
• Secondary lymphoid organs may serve as reservoirs for ILCs involved in inflammatory responses.