New Study Identifies Spleen As Vital Extra-Medullary Hub Supplying Neutrophils For Pulmonary Antiviral Defense

New research reveals the spleen acts as a major reservoir for lung neutrophils during viral infections, offering new targets for treating severe pneumonia.

By: AXL Media

Published: Mar 21, 2026, 7:54 AM EDT

Source: Information for this report was sourced from Immunity & Inflammation

Mapping the Inter-Organ Immune Supply Chain

A groundbreaking study published in the journal Immunity & Inflammation has redefined the scientific understanding of how the body mobilizes immune defenses against respiratory viruses. By utilizing a golden hamster model of SARS-CoV-2 infection, a research team from the Chinese Academy of Medical Sciences tracked the movement of neutrophils—the body's first-responder white blood cells. The team integrated single-cell RNA velocity analysis with spatial transcriptomics to reveal that the spleen acts as a critical reservoir and proliferation hub, sending a continuous stream of neutrophils to the lungs at the height of infection.

Evidence of Splenic Neutrophil Proliferation

The investigation began with a kinetic analysis of lung immune cells, which initially suggested that local lung proliferation was insufficient to account for the total number of neutrophils present during peak inflammation. Between days five and seven post-infection, researchers observed a synchronized spike in neutrophil populations within both the spleen and the lungs. Detailed transcriptomic profiling showed that these splenic and pulmonary neutrophils shared nearly identical gene expression across three stages: proliferative, non-activated, and activated. This molecular signature strongly indicated that the cells accumulating in the spleen were destined for deployment to the lung.

Spatial Deconvolution Confirms Splenic Origin

To prove that splenic cells were seeding the lung tissue, the team employed a sophisticated algorithm known as Redeconve to perform spatial transcriptomic deconvolution. This allowed them to pinpoint the exact origin of various immune cell subsets within the architecture of the lung. The results were definitive: by the seventh day of infection, the proportion of spleen-derived neutrophils in the lung rivaled or even surpassed the number of locally derived cells. Notably, this phenomenon was unique to neutrophils; other immune cell populations remained predominantly lung-derived with minimal splenic input.