What are Türk Cells?
Türk cells, also known as reactive lymphocytes, variant lymphocytes, atypical lymphocytes, or Downey cells, are a type of cytotoxic (CD8+) lymphocyte that increases in size due to antigen stimulation. These cells are significantly larger than typical lymphocytes, often exceeding 30 μm in diameter, with variations in both size and shape. Their appearance is a key characteristic used in identifying them under a microscope. The Merriam-Webster dictionary defines a Türk cell as "a large cell resembling a lymphocyte, having densely basophilic cytoplasm and eccentric nucleus with peripheral chromatin".
- Size: Larger than typical lymphocytes ( >30 μm)
- Shape: Variable, not uniform like typical lymphocytes
- Cytoplasm: Densely basophilic (darkly staining with basic dyes)
- Nucleus: Eccentric (off-center) with peripheral chromatin (chromatin clustered at the edges)
- Cytotoxic (CD8+) Lymphocytes: These cells are involved in killing infected or cancerous cells.
Significance of Türk Cells
The presence of Türk cells often indicates an active immune response to an infection or other antigen. Their identification in a blood smear can help diagnose various conditions, though it is important to note that they are not specific to any single disease. Further investigation is needed to determine the underlying cause of their increased presence.
The research of the Turk lab at Dartmouth, for example, focuses on the response of T cells, including CD8+ T cells which are directly relevant to Türk cell function, to progressive cancers. Their work investigates the mechanisms underlying T cell responses in the context of tumor immunology.
