Introduction to immunology Flashcards
What are the body’s physical barriers to pathogen?
Skin and epithelial mucosa
Secretions
Normal flora
Physiological (temperature, pH)
What are the mechanisms of innate immunity?
Inflammation Recruitment of immune cells Activation of complement Opsonisation Phagocytosis (and endocytosis)
What are some of the common causes of inflammation?
Damage to tissues (burns) Allergens Microbial infection Complement activation Autoimmunity
What is the mechanism of inflammation?
Vasodilation Loosening of endothelial tight junctions Increased cell adhesion molecules Chemotaxis Smooth muscle contraction
What are the different complement pathways?
Classical (via antibodies bound to microbe/antigen)
Lectin
Alternative (direct activation ny microbe)
What is the function of the complement pathways?
Activation of C3
What is opsonisation?
Reduces repellent negative charge of cell membrane to allow phagocyte to come closer. Opsonins include complement, antibodies and plasma proteins
What is the process of phagocytosis?
Phagocyte moves towards microbe
Phagocyte attaches to microbe via opsonin
Endocytosis of microbe within phagosome
Phagosome fuses with lysosome
Oxygen-dependent species result in microbe death
Release of microbe products
What are the antigen presenting immune cells?
Monocytes
Macrophages
Dendritic cells
What are the functions of neutrophils?
Phagocytosis
Degranulation
What are the neutrophil receptors?
Toll like receptors Complement IgG Chemokine IL-8 Chemoattractant C5a ICAM + VCAM - adhesion to endothelium
What are the functions of eosinophils?
Extracellular killing via degranulation, especially of mast cells and basophils
What is the function of basophils?
Degranulation of histamines, prostaglandins and cytokines
What are the basophil receptors?
Surface bound IgE
C3a, C5a
Toll-like receptors
What is the function of mast cells?
Degranulation through cross linking of IgE receptors
What are the mast cell receptors?
Surface bound IgE C3a and C5a Damage associated molecular patterns Toll like receptors Complement
What are the functions of macrophages?
Phagocytosis
Antigen presenting to T cells
Release TNF alpha, IL2 and IL6
What are the macrophage receptors?
Toll like receptors
Fc for IgG and IgA
C3b
MHC class I and II
What are the functions of dendritic cells?
Phagocytosis
Antigen presenting cells to CD4+ T cells via MHCII
Secrete TNF alpha
What are the functions of the natural killer cells?
Bind to and kill virus-infected and cancerous cells
Release of perforin and granzymes from granules
Induce apoptosis
Release INF alpha and TNF alpha
What are the natural killer cells receptors?
Killer activation receptors Killer inhibitory receptors – recognise MHC class I Toll-like receptors Fc receptors Adhesion molecules FasL
