1. Cells and tissues of the immune system Lisbeth N. Fink Nutritional Immunology Group – CBS - DTU

2. Protecting borders to the outside world Challenges 1) Discrimination between self and non-self –bacteria –fungi –vira –parasites –(transplants) 2) Evolution 3) Dealing with non-pathogenic factors

3. First lines of defense Anatomical Skin Mucosae Ciliae Physiological Temperature pH Lysozyme

4. Lymphoid organs and lymphatics

5. Second line of defense: Humoral factors Humor = liquid (From greek, 4 humors controlling health and mood: blood, phlegm, yellow and black bile) Antibodies – specific pathogen recognition Complement system – non-specific recognition Reactive oxygen species (ROS) – bactericidal activity

6. Inflammation – recruitment of cells

7. Third line of defense: Immune cells

8. Haematopoieisis Adaptive/SpecificInnate/Non-specific Leukocytes/ White blood cells Red blood cells Lymphocytes

9. Characteristics of the two parts T cells B cells Antibodies Memory MHC - HLA Diversity Somatic hypermutation Polymorphism Granulocytes Monocytes Macrophages Dendritic cells NK cells NK T cells Complement Pattern recognition Adaptive/SpecificInnate/Non-specific

10. Characteristics of the two parts T cells B cells APC Antibodies Memory MHC - HLA Diversity Somatic hypermutation Polymorphism Granulocytes APC Monocytes APC Macrophages APC Dendritic cells APC NK cells NK T cells Complement Pattern recognition Adaptive/SpecificInnate/Non-specific

11. Antigen uptake - phagocytosis Phagocytic cells: Granulocytes Monocytes Macrophages Dendritic cells

12. Antigen uptake Preference for ”opsonized” bacteria

13. MHC I and II TcTc THTH

14. T cells Helps: B-cells T cells Macrophages Kills: Infected cells Tumour cells Recognizes MHC II on APC Recognizes MHC I on all cells

15. T cell receptor

16. Antigen presentation 3. Signal Cytokines ↔ Cytokine receptors Activation + Proliferation + Help or Killing

17. B cells – plasma cells

18. T cell help for B cell activation

19. B cells – memory cells

20. Meeting places (B – T – APC)

21. What about ’endogenous’ challenges? Cancer cells – tumor antigens Immune reactions within self-tissues: autoimmunity Discontinuation of immune responses …and reactions to harmless environmental factors: allergy (to food, pollen, fur etc.) Immunity vs. Tolerance