Immunity

Introduction.

we are vaccinated against deadly/terminal diseases.

Examples of diseases: Viruses Pathogens Bacteria eg vibrio cholerea

All cells have molecules on their membranes that act as 'markers' for cell recognition, these are usually glycoproteins. If the cell is recognised as 'non-self' white blood cells are activated and destroy the invading cell

Phagocytes are a type of white blood cell, they patrol all cells and tissues, recognise the antigen as being non-self, are attracted to it and then engulf it via phagocytosis, then release lytic enzymes to break the pathogen down.

Antigens are molecules that trigger an immune response.

We are adapted to have barriers that prevent entry to the body: Mucus in trachea Skin Scabs Acid in stomach.

T Cells.

Phagocytes are a non-specific immune response. When pathogen multiply too quickly for phagocytes to remove them, we stimulate a specific immune response. We do this by activating other types of white blood cell that are specific to recognise one antigen. These are called lymphocytes.Some phagocytes become antigen presenting cells - they present the antigen of the engulfed pathogen to the specific lymphocytes called T helper cells.Cell mediated response.T helper cells have a complimentary shape to the antigen and are activated by them, they then divide to form clones that have different roles. More T helper cells to repeat the process and help activate B cells. T Killer cells patrol body for infected cells displaying the pathogen's antigen and kill the cell. T Memory cells for specific antigen to help immunity for the next time the antigen is presented.

T killer cells.These cells kill infected body cells by producing a protein that makes holes in the cell surface membrane of the infected cell. These holes mean the cell becomes freely permeable to all substances and dies as a result. T cells are most effective against viruses because they live inside cells as they need living cells in which to reproduce, thus the body cell is sacrificed.

B Cells.

Humoral Immune Response.

T helper cells are activated, which then activates specific B cells with the same complimentary receptors. The B cell then divides to form clones: Plasma cell that produces antibody proteins that patrol blood B memory cells which help immunity against the antigen.

This and the cell mediated response happen simultaneously. The T Killer cells punch holes into cells to release the virus/bacterium and the antibodies produced by the plasma cells remove it. Antibodies work via; Agglutination - antibodies bind onto the surface of several pathogens creating a bundle, Phagocytes are attracted to the antibodies and phagocytosis occurs Neutralisation - Antibodies surround one pathogen preventing it from attaching and entering other cells. Phagocytes engulf the surrounded pathogen.

Vaccinations.

Stimulate production of antibodies and memory cells against a specific pathogen without causing illness.

Vaccinations contain pathogenic material such as: Dead pathogens killed by heat treatment attenuated pathogen (unable to reproduce) isolated antigens

A vaccination is given and specific T/B memory cells are activated. 1st clones of memory cells are produced. Boosters are then given to make memory cells divide even more, acquiring immunity.

Snakes and spider's biters contain venom, which contains antigens. Antivenom is then needed which is full of antibodies to counteract the venom. We also have general temporary immunity as a foetus and via breast feeding.

Infection then become immune

Vaccination

Maternal

Antibody transfer in pregnancy

Monoclonal Antibodies.

Monoclonal antibodies are antibodies produced from clones of a single plasma cell and are therefore all identical in structure. They all bind with one specific antigen.

They have many uses: Treatment of cancer and other diseases Drug screening Home pregnancy kits Diagnosing diseases. They work by attaching things to the constant region of the antibody such as: Fluoresent Drugs Radioactive markers Enzymes, which when encountering their substrate show a colour change.

INtroduction

T CELLS

B cELLS

vaccinations

Monoclonal antibodies