Recent article summarizing immunological abnormalities in Long COVID
Hey all,
This is a study from December 2025 which investigates a variety of immune biomarkers in Long COVID patients. Previous studies have investigated these markers in isolation; this study conducts a broad investigation of them all. I will be providing my summary and synthesis below, as well as the link to the article. Hopefully it is of value to you.
SUMMARY: The study investigated a Long COVID cohort (n = 28) for immunological, virological, transcriptomic and proteomic abnormalities. I will be focusing on the immunological abnormalities here.
The core finding was abnormal upregulation of the IL6 and JAK-STAT pathways. This is the general-purpose, acute-phase cytokine response the immune system mounts when first encountering an infection (whether viral, bacterial, or parasitic). The fact that this is still upregulated in LC patients many months after the acute infection is over means the immune response that was triggered initially is failing to shut-down completely and is persisting in a chronic, low-grade state.
Secondly, the study found evidence of T Cell exhaustion, with upregulated exhaustion-associated genes in cytotoxic (CD8+) T Cells. Cytotoxic T cells are the T cells responsible for antiviral immunity and keep chronic viruses in the body in check, so this implicates insufficient viral control and potentially higher-than-normal viral reservoirs.
Lastly, many innate immunity biomarkers were abnormally upregulated as well, such as IL1B, the NLRP3 inflammasome, and complement proteins.
As a whole, these findings paint a picutre of a persistently activated, skewed immune response. The innate branch of the immune system is upregulated (IL6, inflammasome, complement) but the cytotoxic T cells of the adaptive branch are exhausted, with downregulation of their cytoxicity. This pattern is common in diseases like Hepatitis C, where essentially after a failed attempt to clear the Hepatitis C virus, the body downshifts the activity of the immune response to prevent excessive damage to the organs.
LINK to article - Long COVID involves activation of proinflammatory and immune exhaustion pathways - https://www.nature.com/articles/s41590-025-02353-x