IL16 (Interleukin-16) encodes a cytokine originally identified as a chemoattractant factor for CD4+ T cells, now recognized as a multifunctional cytokine with roles in immune regulation, neuroinflammation, and cell survival. IL-16 is unique among cytokines as it is synthesized as a propeptide that requires proteolytic processing to become active. In the nervous system, IL-16 is expressed in neurons, astrocytes, and microglia, where it modulates inflammatory responses and may play roles in neurodegenerative diseases[1][2].
| Symbol | IL16 |
| NCBI Gene ID | 3603 |
| Chromosome | 15q22.3 |
| Protein Class | Cytokine |
| Molecular Weight | ~14 kDa (mature form) |
IL-16 has diverse biological functions:
IL-16 is synthesized as a precursor (pro-IL-16) that undergoes proteolytic cleavage:
The unique processing mechanism links IL-16 to apoptosis regulation since caspase-3 is activated during programmed cell death[4].
IL-16 signals through CD4 (cluster of differentiation 4) as a co-receptor:
IL-16 activates multiple pathways:
IL-16 is widely expressed:
| Cell Type | Expression Level | Notes |
|---|---|---|
| Neurons | Moderate | Higher in cortical regions |
| Astrocytes | High | Upregulated in disease states |
| Microglia | High | Constitutive expression |
| T cells | High | Activated T cells |
| Monocytes | High | Constitutive expression |
| Dendritic cells | High | Immature and mature |
IL-16 targeting strategies:
Choi et al. IL-16 in neuroinflammation (2004). 2004. ↩︎
Smith et al. [IL-16 biology (2001)](https://doi.org/10.1016/S0092-8674(01). 2001. ↩︎
Center et al. IL-16 as lymphocyte chemoattractant (1996). 1996. ↩︎
Zhang et al. Caspase-3 and IL-16 processing (1998). 1998. ↩︎
Li et al. IL-16 in Alzheimer's disease (2016). 2016. ↩︎
Mogi et al. IL-16 in Parkinson's disease CSF (2009). 2009. ↩︎
Baranzini et al. IL-16 in multiple sclerosis (2000). 2000. ↩︎