(White Blood Cells)

Leucocytes Specific – 3 rd line Non- specific – 2 nd line

Blood films – Romanowsky stain Red Blood Cells Eosinophil Lymphocyte Basophil Neutrophil Macrophage

Lymphocytes - Types B cells Memory Plasma B M B P T cells Helper Cytotoxic T H T C

Immunity Words Antigen – causes an immune response (usually a pathogen) Antigen – causes an immune response (usually a pathogen) Antibody – protein produced by B cells to destroy specific antigens Antibody – protein produced by B cells to destroy specific antigens

B cells Responsible for Humoral Immunity Responsible for Humoral Immunity Produces antibodies which circulate in the blood and destroy specific antigens Produces antibodies which circulate in the blood and destroy specific antigens Usually effective against pathogens that do not invade cells (eg, bacteria) Usually effective against pathogens that do not invade cells (eg, bacteria)

B cells Memory cells Memory cells Survive for many years (decades) Survive for many years (decades) ‘Remember’ how to make antibodies to a specific disease so that if re-infection occurs, immune reaction is quicker ‘Remember’ how to make antibodies to a specific disease so that if re-infection occurs, immune reaction is quicker Plasma cells Plasma cells Antibody factories Antibody factories Produce a specific type of antibody Produce a specific type of antibody Have a shorter life span than memory cells Have a shorter life span than memory cells

T cells Responsible for Cell-mediated immunity Responsible for Cell-mediated immunity Destroys cells of the body that have been invaded by specific pathogens Destroys cells of the body that have been invaded by specific pathogens Destroy cells mainly by phagocytosis or ‘eating’ them and also by activating other immune cells Destroy cells mainly by phagocytosis or ‘eating’ them and also by activating other immune cells

T cells Cytotoxic T cells (T C or T K ) Cytotoxic T cells (T C or T K ) Kill cells that contain an antigen Kill cells that contain an antigen Generally kill intracellular pathogens such as viruses Generally kill intracellular pathogens such as viruses Helper T Cells (T H ) Helper T Cells (T H ) Activate other T cells and B cells by releasing chemical messengers called lymphokines Activate other T cells and B cells by releasing chemical messengers called lymphokines Triggers white cell replication by releasing cytokines Triggers white cell replication by releasing cytokines

The Immune Response B Y Y Y Y B I I I I B I I I I There are many different types of B cells in our blood which have receptors on their surface that can recognise many different types of antigens Pathogens produce specific antigens B I I I I The antigen will bind to the appropriate B cell, triggering an immune response

Monoclonal Selection B I I I I B I I I I B I I I I B I I I I B I I I I B I I I I B I I I I B I I I I I I I I I I I I I I I I I I I I I B I I I I Plasma Cells Memory Cells B I I I I Antibody production Proliferation

Antibodies Antibodies bind to antigens and destroy them by puncturing them and attracting phagocytes and T cells to them

Lymphocyte interaction Antigen BTHTH TCTC THTH THTH BMBM BPBP I I TCTC TCTC Chemical Activation Directly attack infected cells

Other T cells Two other types of T cells exist: Two other types of T cells exist: T suppressor cells T suppressor cells De-activate immune response when the antigen is gone (opposite of helper cells) De-activate immune response when the antigen is gone (opposite of helper cells) Natural Killer Cells Natural Killer Cells Specifically kill tumour cells in a similar way to cytotoxic cells killing infected cells Specifically kill tumour cells in a similar way to cytotoxic cells killing infected cells Both cell types are not well understood Both cell types are not well understood