Lymphoid Tissue Inducer Cells (LTi cells)

LTi Cells Build Secondary Lymphoid Organs

Lymphoid Tissue Inducer (LTi) cells are a specialized subset of group 3 innate lymphoid cells (ILC3s). They are crucial for developing secondary lymphoid organs, including lymph nodes and Peyer’s patches. LTi cells also support the activation and function of T and B cells. Their distinct gene-expression profile, developmental origin, and functions distinguish them from other ILCs and conventional natural killer cells, supporting their recognition as a separate innate lymphoid lineage (1, 2).

Lymphoid Tissue Inducer Cells Markers Identify Their Immune Phenotype

Key phenotypic markers used to identify LTi cells include CCR6+, CD117+, CD127+, C-X-C chemokine receptor type 6 (CXCR6)+, NKp46−, and Thy1.2+. These markers help distinguish LTi cells from related immune-cell populations and clarify their roles in immune responses (3).

RORγt and PLZF Control LTi Cell Development

The transcription factors RAR-related orphan receptor gamma/t (ROR-gamma/t) Isoform 2 (NR1F3) and PLZF / zinc finger and BTB domain-containing protein 16 regulate gene expression associated with immune-cell development and function. These factors are important for establishing and maintaining the LTi-cell program (3).

IL-1β and IL-23 Activate LTi Cells

LTi-cell activity is influenced by inflammatory stimuli, particularly interleukin-1 beta (IL-1β) and interleukin-23 (IL-23). These cytokines activate and modulate immune responses and contribute to inflammatory signaling (3)

IL-17 and IL-22 Drive LTi Effector Function

LTi cells produce signature cytokines, including interleukin-17 (IL-17), interleukin-22 (IL-22), and lymphotoxin. These mediators help coordinate host defense against pathogens and other external threats (3).

LTi Signals Connect Development and Immunity

The relationships among LTi-cell markers, transcription factors, activating stimuli, and effector cytokines provide a framework for understanding innate immune regulation and for developing targeted therapeutic strategies (3).

References

(1) Zhong et al. 2018 Cytokine Growth Factor Rev. 42: 5-12
(2) Willey et al. 2023 McGraw Hill, USA, ISBN 978-1-265-12303-1
(3) Ng & Belz 2023 Trends in Cancer 9(2): 158-171

see also:
Citrobacter rodentium
Common Lymphoid Progenitor Cells / Lymphopoiesis (CLPS)
Immune responses