physiology and immunology

what is the difference between innate and adaptive immunity?

Innate:

• non specific

• rapid

• does not improve on repeated contact with invading organism

• relies on generic pathogen associated molecular patterns (PAMP’s) and PRR’s

adaptive:

• specific

• slow

• acquired responses not encoded in the germline

• result from genetic rearrangements of genes involved in recognition

• a specific receptor for each invading organism is selected from a randomly created repertoire of receptors

Phagocytosis

• primarily innate immunity but also plays crucial role in initiating adaptive immune responses

• move towards pathogen

• make contact

• engulf - phagosome

• fusion with lysosome

• killing - toxic chemicals

• digest remains

innate immunity in invertebates

• found in all animals

• invertebrates with few exceptions only have innate immunity

proteins:

• antimicrobial peptides

• complement (system of proteins that help destroy proteins)

cells:

• phagocytes

• crystal cells (immune cell in insects, seal wounds)

• lamellocytes (type of immune cell found in insects that trap invaders)

innate immunity in vertebrates

• like invertebrates both humoural and cell mediated response

• circulatory system with blood delivers the response rapidly to where its needed

• molecules and cells diffuse out of capillaries into tissue fluid around cells

• interferons mediate viral innate immunity (send out warning signals when virus) - increase resistance of cells to infection, slow the spread of disease

• complement system - attacks and breaks down cell walls, attracts phagocytes and stimulates inflamation

• fever- body temp rises in repsonse to pyrogens, inhibits pathogens

• phagocytes- remove debris and pathogens

• extracellular killing - destroys abnormal cells

mammalian adaptive immunity

• specifity

• memory

• tolerance to self and harmless antigens

1. humoural immune reponse mediated by antibodies produced by B lymphocytes

2. cellular immune reponse mediated by T lymphocyes

what is an antigen?

• antigen = antibody generator

• substances that bind to receptors on immune cells

• typically a small subsection of an antigen, an epitope binds to the receptor

B lymphocytes

• mature to have a unique membrane receptor that recognises a specific antigen

• after interacting with the antigen the b cell proliferates

• these cells differentiate into specific antibody secreting B cells

• antibodies are immunoglobins that bind to specific antigens

• antibody tagged antigens are recognised for disposal by effectors such as complement or macrophages

• B memory cells are also made

T lymphocytes

• mature in thymus gland and produce t cell receptors

• there are subpopulations of t lymphocytes like t helper cells and cytotoxic t cells

• TCR’s and BCR’s only fir one key and open it

How is diversity in TCR and BCR’s produced?

• somatic recombination and splicing