Overview of T-cells Structures and functions

1. T-Cells

2. Development of T-Cells

3. Thymic selection of T-Cells

4. Types of T-Cells
• CD4+ cells or TH-Cells TH
0 , TH
1 , TH
2
• CD8+ cells or Cytotoxic T-Cells
• Regulatory T-Cells

5. Activation of T-Cell
Clonal
expansion
Signals: antigen, inter leukins,B7 protein co-stimulation

6. Functions of T-Cells
• TH-Cells: activation of B-Cells, secretion of cytokines,
delayed type hypersensitivity.
• Cytotoxic T-Cells: kills cells infected with bacteria and virus,
kills tumor cells and transplanted foreign cells during graft
rejection.
• Regulatory T-Cells: suppress immune response of T-Cells by
regulating the population of T-Cells, prevent pathological self
reactivity inhibiting auto immune diseases.

7. TH 1 T-Cells FUNCTION
IL-2 T-Cell growth factor
IL-3 Involved in hematopoesis
IFNγ Activates macrophages
TNFβ Inflammatory responses
TH 2 T-Cells FUNCTION
IL-3 Hematopoesis
IL-4 Activates B-Cells
IL-5 Ativates B-Cells
IL-10 Inhibits macrophages
IL-13 B-Cells growth factor
Cytokines produced by T-Cells

8. T-Cell mediated B-Cell
activation
Effector cells and
memory cells

9. Cell mediated immunity by CTL

10. Interaction of T-Cells with antigen
CD4+ T-Cells CD8+ T-Cells

11. Immuno receptor
tyrosine based
activation motif
Variable region
Constant region

12. T-cells and autoimmune diseases
• Insulin dependent diabetes mellitus-pancreatic-β cells
• Rheumatoid arthritis-connective tissue
• Multiple sclerosis-white matter
• Hashimoto’s disease-thyroid proteins and cells
Immune disorders involving the thymus
• Digeorge syndrome
• Nezelof syndrome
Immuno deficiency
• AIDS

13. Conclusion
T-Cells play crucial role in recognition of processed antigen and
it connects humoral immunity to cell mediated immunity