(White Blood Cells)(White Blood Cells)

LeucocytesLeucocytes

Specific – 3rd line

Non- specific – 2nd line

Blood films – Romanowsky stainBlood films – Romanowsky stain

Red Blood Cells Eosinophil

LymphocyteBasophil

Neutrophil

Macrophage

Lymphocytes - TypesLymphocytes - Types

B cellsB cells

MemoryMemory Plasma PlasmaBBMM BBPP

T cellsT cells

HelperHelper Cytotoxic CytotoxicTTHH TTCC

Immunity WordsImmunity Words AntigenAntigen – causes an – causes an

immune response immune response (usually a pathogen)(usually a pathogen)

AntibodyAntibody – protein – protein produced by B cells to produced by B cells to destroy specific destroy specific antigensantigens

B cellsB cellsResponsible for Responsible for Humoral Immunity Humoral Immunity

Produces Produces antibodiesantibodies which circulate in the which circulate in the blood and destroy specific antigensblood and destroy specific antigens

Usually effective against pathogens that do Usually effective against pathogens that do not invade cells (eg, bacteria)not invade cells (eg, bacteria)

B cellsB cellsMemory cells Memory cells

Survive for many years (decades)Survive for many years (decades) ‘‘Remember’ how to make antibodies to a Remember’ how to make antibodies to a

specific disease so that if re-infection occurs, specific disease so that if re-infection occurs, immune reaction is quickerimmune reaction is quicker

Plasma cellsPlasma cellsAntibody factoriesAntibody factoriesProduce a specific type of antibodyProduce a specific type of antibodyHave a shorter life span than memory cellsHave a shorter life span than memory cells

T cellsT cellsResponsible for Responsible for Cell-mediated immunityCell-mediated immunity

Destroys cells of the body that have been Destroys cells of the body that have been invaded by specific pathogensinvaded by specific pathogens

Destroy cells mainly by Destroy cells mainly by phagocytosisphagocytosis or or ‘eating’ them and also by activating other ‘eating’ them and also by activating other immune cellsimmune cells

T cellsT cellsCytotoxic T cells (TCytotoxic T cells (TCC or T or TKK) )

Kill cells that contain an antigenKill cells that contain an antigenGenerally kill intracellular pathogens such as Generally kill intracellular pathogens such as

virusesviruses

Helper T Cells (THelper T Cells (THH))Activate other T cells and B cells by releasing Activate other T cells and B cells by releasing

chemical messengers called lymphokineschemical messengers called lymphokinesTriggers white cell replication by releasing Triggers white cell replication by releasing

cytokinescytokines

The Immune ResponseThe Immune Response

B

Y

Y

Y

Y B

I

I

I

I B

I

I

I

IThere 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

II

I

The antigen will bind to the appropriate B cell, triggering an immune response

Monoclonal SelectionMonoclonal Selection

B

I

I

I

I

B

I

I

I

IB

I

II

I

B

I

I

I

I

B

I

I

I

I B

I

I

I

I

B

I

I

I

IB

I

I

I

I

II

I

III

I

I

I

I

I

I

I

I

I

I

I

B

I

I

I

I

Plasma Cells

Memory Cells

B

I

I

I

IAntibody

production

Proliferation

AntibodiesAntibodies

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

Lymphocyte interactionLymphocyte interaction

Antigen

B TH TC

TH TH

BM BP I

ITC TC

Chemical Activation

Chemical Activation

Directly attack infected cells

Other T cellsOther T cells Two other types of T cells exist:Two other types of T cells exist:

T suppressor cellsT suppressor cells De-activate immune response when the antigen is gone De-activate immune response when the antigen is gone

(opposite of helper cells)(opposite of helper cells)

Natural Killer CellsNatural Killer Cells Specifically kill tumour cells in a similar way to cytotoxic cells Specifically kill tumour cells in a similar way to cytotoxic cells

killing infected cellskilling infected cells

Both cell types are not well understoodBoth cell types are not well understood