8. Inflammatory Cells And Their Functions Flashcards
Neutrophils
Phagocyte anddestory forgein antigens and microbial organisms
Main solders
Contain antimicrobial functions
Eosinophils
When stimulated release inflammatory factors which destroy parasites and trigger a histamine release from mast cells
Allergic reactions
Basophils
Role in allergic response, protective immunity in skin, eradication of parasites
High affinity for IgE
Mast cells
Source of mediators of immediate hypersensitivity
Have many receptors for IgE
Release mediators of allergic disease: histamine and prostaglandins
Monocytes/macrophages
In blood - in tissue become macrophages
Big eaters of immune system
ORIGIN: in adults hematopoietic stem cells in bone marrow
In fetus: hematopoietic stem cells in bone marrow and yolk sac, differentiate into a variety of organs
Three steps of Phagocytosis
Recognition and attachment
Engulfment
killing by ROS, NO or degraded by lysosome
Reactive Oxygen Species
Oxygen-derived free radicals (including H2O2 and hydroxyl radical) are released from a variety of inflammatory cells once activated
EFFECTS: endothelial cell damage cause it increased vascular permeability, injury through oxidative stress
Role of mediators of inflammation
Initiate and regulate inflammation
Secreted by cells or made from plasma proteins
Active mediators produced in response to stimuli
Short-lived
One mediator can stimulate release of other mediators
Principle mediators of inflammation
Histamine Prostaglandin Leukotrienes Cytokines (TNF, IL-1) Chemokines Complement system
Histamine
Source: mast cells
Action: vasodilation, increase vascular permeability
Prostaglandins
Source: Cell membrane phospholipid
Action: vasodilation, pain, fever
Leukotrienes
Source: cell membrane phospholipid
Action: increase vascular permeability
Cytokines (TNF, IL-1)
Source: macrophages, helper T cells
Action: Local- endothelial activation
Systemic- fever
Chemokines
Source: leukocytes, activated macrophages
Action: chemotaxis
Complement system
Source: plasma (produced in liver)
Action: direct target killing MAC
Vasoactive amines
Histamine and serotonin - first mediators of inflammation
Serotonin - main source are platelets not mast cells
histamine - stored in mast cells and released when they degranulate
Release of Histamine
Released through degranulation of mast cells
Binding of antibodies to mast cells (allergy/IgE0
Products of complement activation - anaphlytoxins (C3a and C5a) stimulate release of histamine
Arachidonic Acid Metabolites
Lipid mediators produced from arachnoidic acid in phospholipid
Prostaglandins
Leukotrienes
Lipotoixins
Prostaglandins
Generated by cyclooxygenases
COX-1 : expressed in tissue
COX-2: induced by inflammatory stimuli
Leukotrienes
Generated by lipoxygenase
Involved in vascular/smooth muscle response and leukocyte recruitment
Lipotoxins
Generated by lipooxygenase
Suppress inflammation by inhibiting recruitment of leukocytes - do not allow neutrophils to come to site of inflammation
Cytokines
Proteins produced mainly by activated macrophages and T cells
Significance: they mediate and regulate immune and inflammatory reactions
Chemokines
Proteins (sub family of cytokines) that stimulate recruitment of leukocytes
significance: induce chemotaxis - attract neutrophils to site of action
Sequential steps of inflammation
- Recognition of offending agent
- Recruitment of leukocytes and plasma proteins
- Removal of agent
- Resolution
