From the Guidelines
A high percentage of CD8 cells typically indicates an active immune response, particularly against viral infections or other intracellular pathogens. CD8 cells, also known as cytotoxic T lymphocytes, are white blood cells that destroy infected or abnormal cells in the body. Elevated CD8 levels can occur during acute viral infections like HIV, hepatitis, or CMV, as well as in certain autoimmune disorders, some cancers, and following organ transplantation. The significance depends on the clinical context and should be interpreted alongside other immune markers like the CD4/CD8 ratio, which is normally between 1.5-2.5 in healthy adults. A persistently inverted ratio (below 1.0) with high CD8 counts may suggest chronic immune activation or immunodeficiency. Some key points to consider when evaluating CD8 cell counts include:
- The clinical context in which the CD8 cell count is being interpreted, as this can significantly impact the significance of the results 1.
- The use of other immune markers, such as the CD4/CD8 ratio, to provide a more comprehensive understanding of the immune response 1.
- The potential for elevated CD8 levels to occur in response to a range of conditions, including viral infections, autoimmune disorders, and cancers 1. If you have elevated CD8 cells, your healthcare provider may recommend additional testing such as viral studies, complete blood counts, or other specialized immune testing to determine the underlying cause. No specific medication is typically prescribed solely for high CD8 counts, as treatment targets the underlying condition causing the elevation. It's worth noting that recent studies have highlighted the importance of considering the activation status of CD8 T cells, as well as their absolute counts, when evaluating immune function 1. Overall, the interpretation of CD8 cell counts requires careful consideration of the clinical context and the use of other immune markers to provide a comprehensive understanding of the immune response.
From the Research
CD8 Cells and Autoimmunity
- CD8+ T cells can contribute to the initiation, progression, and regulation of autoimmune responses by killing target cells directly or indirectly, and by secreting cytokines and chemokines 2.
- These cells can also downregulate autoimmune responses, highlighting their complex role in autoimmunity 2.
- The importance of CD8+ T cells in autoimmune diseases is being increasingly recognized, with studies showing that they can promote or prevent disease development through various mechanisms 3.
CD8 Cells and Infection
- CD8+ T cells play a crucial role in defense against viral and bacterial infections, as well as in tumor immunity 4.
- However, their functionality can be impaired in certain conditions, leading to a state of dysfunction 4.
- A high percentage of HLA-DR+CD38high CD8+ T cells has been associated with immune disorder and disease severity in COVID-19 patients, suggesting a potential link between CD8+ T cell dysfunction and disease outcome 5.
CD8 Cell Subsets and Functionality
- CD8+ T cells are heterogeneous and can be divided into different subsets with distinct characteristics, such as HLA-DR+CD38dim and HLA-DR+CD38hi 5.
- These subsets can have different functional activities, with HLA-DR+CD38hi CD8+ T cells being associated with overactivation, dysregulation, and impaired killing potential 5.
- Understanding the different CD8+ T cell subsets and their functional activities can provide valuable insights into their role in autoimmunity and infection 6.