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Medical News: COVID-19 Severity and Immune System Changes
Researchers from George Emil Palade University of Medicine, Pharmacy, Science, and Technology, Romania, have discovered that lymphocyte (white blood cell) shifts in COVID-19 patients can indicate disease severity and predict outcomes. This
Medical News report explores their findings, which shed light on how immune cells respond in severe cases of COVID-19. By studying lymphocyte changes, the team aimed to better understand why some patients experience mild symptoms while others face life-threatening complications.
Lymphocyte Shifts in COVID-19 Linked to Severity and Outcomes
The Study and Its Findings
The study included 53 COVID-19 patients at Târgu Mureș, Romania, classified into mild, moderate, and severe groups. Blood tests tracked the types and numbers of lymphocytes, including CD3+, CD4+, CD8+, and NK cells. The results revealed that patients with severe COVID-19 had significantly lower CD3+ (T cells), CD4+ (T-helper cells), and CD8+ (T-cytotoxic cells) counts compared to those with mild or moderate cases. The researchers discovered a striking correlation between lower lymphocyte levels and more severe outcomes, and this study highlights that dynamic changes in these immune cells can be an indicator of disease progression.
Differences Between Severity Groups
The study showed that the immune response varied considerably depending on disease severity. Patients with mild COVID-19 retained relatively stable lymphocyte levels throughout hospitalization. However, moderate and severe cases saw substantial drops in CD3+ cells early in hospitalization, with slight recoveries over time. In severe cases, patients also had reduced CD3+/CD19+ ratios (the balance between T and B cells) and CD3+/NK ratios (T cells to natural killer cells). Lower NK cell counts and CD4+ cells were noted from day one, further highlighting the weakened immune response in severe cases.
Lymphocyte Changes During Recovery
The study monitored lymphocyte counts over ten days to observe recovery trends. Patients with moderate and severe disease showed an increase in CD4+ and CD8+ cells by day 10, suggesting that a gradual return of these cells may be associated with recovery. However, in severe cases, CD8+ T-cell levels remained lower than in milder cases, a pattern that potentially signaled delayed immune function recovery.
Another key finding was the relationship between these immune markers and mortality risk. Patients who did not survive COVID-19 had significantly fewer CD3+ and CD4+ cells. Using the CD3+ lymphocyte count, researchers were able to predict disease outcomes with an area under the curve (AUC) score of 0.723, a measure of the model’s accuracy. When combined with biomarkers like ferritin and the neutrophil-to-lymphocyte ratio (NLR), as well as factors like age and oxygen saturation (SpO2), the prediction model's AUC rose to 0.927, suggesting that these markers together could be a strong tool in assessing patient risk.
Immune Exh
austion and PD-1 Markers
An important factor the study looked at was immune cell exhaustion, a condition in which T cells lose their effectiveness due to prolonged activation. The PD-1 marker, an indicator of this exhaustion, was more prominent in CD4+ and CD8+ cells of non-survivors, pointing to a compromised immune response. Elevated PD-1 levels in severe cases align with previous studies on SARS-CoV-2 infection and immune cell exhaustion, reinforcing that the body’s defense system might become overwhelmed in more severe COVID-19 cases.
Implications for Predicting Patient Outcomes
The study's insights could prove helpful for healthcare providers in determining which COVID-19 patients might face more severe outcomes. By monitoring T-cell and NK cell counts early on, physicians may be able to assess disease severity and make quicker, more effective treatment decisions. This approach could become a valuable addition to hospital protocols, particularly for high-risk patients.
Broader Applications and Future Directions
Researchers hope to expand this work to examine long-term immune response changes in COVID-19 patients, especially those with lingering symptoms, often called “long COVID.” Additionally, studying how various SARS-CoV-2 variants influence immune cells might help tailor treatments for future waves of COVID-19 or similar diseases.
The study findings were published in the peer-reviewed journal: International Journal of Molecular Sciences.
https://www.mdpi.com/1422-0067/25/22/11921
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Read Also:
https://www.thailandmedical.news/news/the-role-of-cytotoxic-lymphocyte-monocyte-complexes-in-covid-19-immune-responses
https://www.thailandmedical.news/news/azvudine-shows-potential-in-shortening-hospital-stays-and-improving-lymphocyte-counts-in-patients-with-non-severe-covid-19
https://www.thailandmedical.news/news/decoding-long-covid-19-how-interferon-lambda-modulates-t-lymphocyte-pd-1-via-the-akt-gsk3beta-pathway
https://www.thailandmedical.news/news/breaking-covid-19-news-brazilian-researchers-discover-that-sars-cov-2-uses-cd4-to-infect-t-helper-lymphocytes
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