The immune response White Blood cell types

Myeloid stem cells Lymphoid cells Pluripotent stem cells (in bone marrow) Monocyte Mast cells Basophils Neutrophils Eosinophils Macrophage Granular Lymphocytes (NK cells) T- Lymphocytes (mature in thymus) Dendritic cells B- Lymphocytes (mature in bone marrow) Cytotoxic T-cell Helper T-cell Suppressor cell T-memory cell Plasma b cell Memory b cell

Mast cells Found in connective tissues of the body Release histamine to start inflammation response Return

Basophils Effectively circulating mast cells Send signals to activate / recruit other myeloid cells Return

Neutrophils Phagocytosis Most common of the myeloid cells Perform phagocytosis Return

Phagocytosis Release chemical to reduce inflammation response Eosinophils Return

Monocyte Very inactive until stimulated by antigen with non self HMC Will differentiate into either dendritic or macrophage Very large Dendritic cells Phagocytosis Antigen presenting cell (engulf foreign objects and displays antigen markers to T and B cells) Found outside body on mucus membranes, etc Macrophage Phagocytosis Found in blood stream Antigen presenting cell (engulf foreign objects and displays antigen markers to T and B cells) Return

Natural killer cells Cause cell apoptosis on diseased cells These cells with have foreign antigens on surface Secretes two chemical 1. punches hole in cell 2. sends signal to self destruct Return

Cytotoxic T-Cell Destroys Virus infected / cancerous cells (similar to the NK cells) Return

Helper T-Cell Activate Cytotoxic T cells and Macrophages Return

Suppressor / Regulatory T cells Stops the immune response (opposite to T- cells) Return

T-memory cells Remain long after immune response Numbers increase rapidly when exposed to previously seen antigen (provide memory for immune system) Return

Plasma b cells Produce large amounts of antibodies (proteins) which assist in the phagocytosis process Return

Memory b cells Activate plasma b cells that create antibodies specific to the antigen detected Return

Clonal selection Both b and t cells under go a process by which their Antigen receptors are randomly altered during every division. This creates an array of different antigen binding sites in the body which is important due to binding specificity (much like enzymes)

The Humoral response Killing foreign cells Macrophage / Dendritic cells consume pathogens and place their antigen on their own surface These markers are delivered to the helper T cells in the lymph nodes Lymph nodes

In the lymph nodes The Macrophages / Dendritic cells present the antigens to the Helper T-cells

Cytotoxic t-cells and Plasma b cells B-cells will bind with antigens around the body however they will wait motionless unless a Helper T cell finds the same antigen

Helper T - Cells If the Helper T cell is presented with the same antigen as a b-cell has found it will send an INTERLUKEN which is a signal for action

B-cell proliferation Once given the signal, The b cells clone themselves into more plasma b-cells and start producing antibodies at a rapid rate (10k per second) The antibodies - Neutralise toxins - Prevent further binding - attract phagocytic cells

Antibodies 5 classes of antibodies G,M,A,D,E G – lots made, can cross membranes easily M – type made first E – Attach to mast cells and make them more sensitive. Over production can lead to allergies

Memory b-cells Some of the b-cells created are called memory b-cells These cells are long lasting (up to 10 years) and will act as the “memory” of the immune system The next time that particular type of antigen enters the body, it only needs to come in contact with one memory b cell and the proliferation process will occur again This will result in a far faster destruction of the pathogen in future

When a pathogen enters the body for the first time it will go un challenged until both a helper T cell and a b-cell find it After memory b-cells have been created, the pathogen is far more likely to be discovered quickly and eliminated

The Cell Mediated Response Killing our bad cells T-cell receptor - Antigen receptor CD8 receptor - MHC recognition Cytotoxic T-cells have two receptors The CD8 receptor helps the cell identify whether a cell belongs to the body or not by checking the cells MHC The Antigen receptor allows the t-cell to determine whether a pathogen has been present and left its markers on the cell

Diseased cell If the CD8 Receptors match – means it is a self cell If the T-cell receptor matches – means the t cell will wait for a signal from a helper t cell to indicate that this is in fact an antigen that needs to be destroyed

Diseased cell If a helper t cell has been presented with an antigen that is the same as the markers on the cell it will send a CYTOKINE to allow the destruction of the cell

Diseased cell The cytotoxic t-cell will then use two chemicals to destroy the cell, as well as create many copies of itself which will seek out other identical cells and do the same

overview