ILC (Innate lymphoid cells)

ILC1

Origin: CLP (common lymphoid progenitor) --> CILP (common innate lymphoid progenitor) --> CHILP (common helper innate lymphoid progenitor) --> ILCP (innate lymhoid cell precursor)--> ILC1

Location: the dominant ILC subset present in the liver. Their production of IFN–γ promotes the survival of hepatocytes.

Function: Type 1 immunity (macrophage activation, cytotoxicity)

Effector molecules: IFNgamma, Granzymes, Perforin (low levels)

Phenotypical characteristics: CD45, can express CD49a and TRAIL, but often lost upon cell activation and tissue dependent; NKp44, CD127

Functional characteristics:

  • TF: Tbet

ILC2

Origin: CLP (common lymphoid progenitor) --> CILP (common innate lymphoid progenitor) --> CHILP (common helper innate lymphoid progenitor) --> ILCP (innate lymhoid cell precursor)--> ILC2

Location; tissue-resident, imprinted by the tissue of residence ( generally presence of ILC in non-lymphoid tissue is ensured by recruitment of ILC progenitors from blood and maintained by the expression of local survival factors, such as IL-7. ... ILC2 generally circulates in bloodstream though

Function: innate counterpart to Th2, responds to large extracellular pathogens and allergens, they regulate adaptive immunity, tissue remodelling/repair and homeostasis of NHSCs / HSCs. Regulation of crosstalk of lymphoid cells with NHSc + spatial organization of immunity

Effector molecules: IL5 + IL 13 (type 2 cytokines)

Phenotypical characteristics: CD45+, CD127+, ST2+/-, CD278 (ICOS) ++, IL17-R-beta + , CD294 +

transcriptional characteristics:
specific for ILC2 = GATA3, ROR-alpha

NKcells

Origin: CLP (common lymphoid progenitor) --> CILP (common innate lymphoid progenitor) --> NKP (NK cell precursor) --> NK

Location: NK cells develop in bone marrow as well as in some extramedullar sites, such as lymph nodes, thymus, liver, and uterus.

Function: Type 1 immunity (macrophage activation, cytotoxicity)
mirror the functions of CD8+ cytotoxic T cells

Effector molecules: IFNgamma, Granzymes, Perforin

Phenotypical characteristics: CD45, KLRG1, NKp46, CD122, CD56

Functional characteristics:

  • TF:Tbet, Eomes

ILC3

Origin: CLP (common lymphoid progenitor) --> CILP (common innate lymphoid progenitor) --> CHILP (common helper innate lymphoid progenitor) --> ILCP (innate lymhoid cell precursor)--> ILC3

Location; tissue resident, however often migrates to intestinal lamina propria & draining mesenteric lymph node

Function counterpart to Th17: combat extracellular microbes (bacteria/funghi)

Effector molecules:
produce IL-17 or IL-22

Phenotypical characteristics: ILC3 3 subtypes (either LTi, NKp46+ / NKp46-)

transcriptional characteristics:
3 subtypes which all depend of ROR-gammaT transcription factor