Linoleoyl-lysophosphatidylcholine drives non-inflammatory apoptosis in neutrophils via lipid rafts.

Lysophosphatidylcholines (LPCs) are among the most abundant circulating bioactive lipids, whose fatty acid compositions critically influence their immunomodulatory functions. Alterations in circulating LPC species have been implicated in inflammatory settings, including immune checkpoint blockade-associated immune-related adverse events (ICB-irAEs), yet how individual LPC species shape innate immune cell fate remains poorly defined. Here we investigated how unsaturated linoleoyl-LPC (LPC 18:2) and saturated palmitoyl-LPC (LPC 16:0) differentially regulate neutrophil survival and inflammatory responses through distinct cell-intrinsic mechanisms in vitro. In mature peripheral human neutrophils, LPC 18:2 markedly increased intracellular reactive oxygen species (ROS) generation and caspase-3/7 activation accompanied by mitochondrial membrane depolarization and cytochrome c release, consistent with activation of the intrinsic apoptotic pathway. In contrast, LPC 16:0 induced lower levels of ROS and elicited caspase-3/7 activation with a distinct dose-response profile to LPC 18:2. These were accompanied by lactate dehydrogenase (LDH) and high mobility group box 1 (HMGB1) release, as well as increased myeloperoxidase (MPO) activity, neutrophil elastase (NE) release, and citrullinated H3, indicating membrane rupture, NETosis-associated activity, and induction of a lytic form of cell death with damage-associated molecular pattern (DAMP) release. Bulk RNA sequencing revealed that LPC 16:0 strongly upregulated inflammatory and cytokine-associated gene expression programs, whereas LPC 18:2 treatment was largely transcriptionally quiescent. Disruption of lipid raft integrity through cholesterol depletion abolished LPC 18:2-induced intracellular ROS production and apoptosis, demonstrating a requirement for membrane organization in mediating these effects. Collectively, these findings identify LPC 18:2 as a non-inflammatory, lipid raft-dependent inducer of mitochondria-driven neutrophil apoptosis, whereas LPC 16:0 promotes inflammatory and lytic death pathways. These results highlight lipid saturation as a key determinant of neutrophil fate and immune tone, providing insight into how distinct LPC species may shape inflammation and tissue injury, including in the context of neutrophilic immunotherapy-associated toxicities.