Innate and adaptive immunity

What are the different forms of first line of defence

• Mechanical

• Molecular and cellular

• Microbiological and environmental

What are the different mechanical first line of defences

• Body surface

• Cilia in respiratory tract

• Air movement in respiratory tract

• Flushing by liquids

• Mucus as barrier

What are the different physiological first line of defences

• pH changes and extremes

• Pyrexia kills some infectious agents

What are the different cellular innate defences

• Macrophages - function by ingesting and killing microorganisms

• Neutrophils - also phagocytic and degranulate

• Mast cells, basophils and eosinophils - have receptors for antibodies and increase vascular permeability

Which one is a monocyte

Which one is a macrophage

Which one is a neutrophil

Which one is a basophil

Which one is an eosinophil

What are the different molecular defences

• Defensins

• Lysozyme and sweat gland secretions

• Myeloperoxidase system

• Acute phase proteins

• Complement systems

• Interferons

What are defensins

Small 15-20 aa proteins

Where are defensins found

In many tissues and cells, especially phagocytes and epithelial cells

What are defensins active against

• Bacteria

• Fungi

• Viruses

What are defensins important in

Skin barrier to infections

What are lysozymes

Family of enzymes which attach peptidoglycan cell walls of bacteria

What are the sites of action of lysozymes

• Cellular

• Secreted from epithelial cells

• Sebum

How do lysozymes act on cells

In cytoplasmic granules of macrophages

How are lysozymes secreted from epithelial cells

• Tears

• Saliva

• Mucus

How do lysozymes act in sebum

• From sebaceous glands

• Waxy fatty acids stop bacterial attachment to skin

• Hydrates and lubricates skin

What is myeloperoxidase

An enzyme found mainly in lysosomes in granulocytes and macrophages

What do myeloperoxidases do

Kill bacteria and other pathogens by production of toxic hypochlorite and singlet oxygen

How do commensal bacteria work

• Inhabit mucosal surfaces, especially in GI and respiratory tracts and skin

• Prevent attachment of pathogenic bacteria and hence block their invasion and infection

What husbandry factors effect innate immunity

• Diet

• Temperature

• Humidity

What are the defining features of adaptive immunity

• T and B cells

• Specificity

• Self and non self discrimination

• Memory

What is an antigen

Any molecule that can bind specifically to an antibody or antigen receptor

What is an epitope

A site on an antigen recognized by an antibody or an antigen receptor

What is an antibody

A protein that binds specifically to a particular substance

What are the stages of action of defending against microbial invasion

1. Invading microorganism passes physical barriers

2. Innate immunity such as inflammation, defensins and lysozymes

3. Specific immunity such as antibody production and cell mediated immunity