iAge (immune age clock)

iAge is an inflammatory-age metric introduced by Sayed and colleagues (2021, Stanford) that uses a deep-learning model trained on a panel of 50 circulating cytokines and chemokines from 1,001 healthy individuals across the decade-long Stanford 1000 Immunomes Project. The model compresses the immunome profile into a single inflammatory-age score that predicts cardiovascular risk, multimorbidity, and all-cause mortality independently of chronological age. CXCL9—a chemokine associated with T-cell recruitment and endothelial dysfunction—was identified as the single most informative driver. The clock highlights the immune system as a distinct, targetable dimension of biological ageing.