Th1
1. Neuroanatomy: Thoracic Spinal Segment 1 (T1)
Th1 refers to the first thoracic spinal segment.
Location
- Situated between cervical segment C8 and thoracic segment T2
- Corresponds approximately to the first thoracic vertebra (T1)
Function
- Origin of spinal nerves T1, which contribute to:
- Brachial plexus (particularly the inferior trunk)
- Sympathetic preganglionic neurons in the intermediolateral cell column (IML)
- Part of the thoracolumbar outflow of the sympathetic nervous system
Clinical Relevance
- Lesions at Th1 may cause:
- Horner syndrome (ptosis, miosis, anhidrosis) due to disruption of sympathetic fibers
- Motor or sensory deficits in the medial arm/forearm
2. Immunology: T Helper 1 Cells (Th1)
Th1 cells are a subtype of CD4+ T helper lymphocytes that orchestrate the cell-mediated immune response.
Function
- Activate macrophages and cytotoxic T cells
- Promote defense against intracellular pathogens (e.g., viruses, some bacteria)
Cytokine Profile
- Secrete Interferon-gamma (IFN-γ), IL-2, TNF-α
- Stimulated by IL-12 (from dendritic cells/macrophages)
Clinical Relevance
- Th1 dominance is associated with:
- Autoimmune diseases (e.g., type 1 diabetes, multiple sclerosis)
- Resistance to tuberculosis
- Imbalance between Th1/Th2 responses affects immunity and hypersensitivity patterns