Immune SystemImmune SystemWorking around the clock to endorse and fortify our healthWorking around the clock to endorse and fortify our health

Antigen presentationAntigen presentation

Macrophage cuts the pathogen into pieces and Macrophage cuts the pathogen into pieces and exposes itexposes it’’s antigen on its antigen on it’’s cell surface s cell surface membrane membrane

T-T-LymphocyteLymphocytessactivateactivateT-Lymphocytes activate by encountering their specific antigen T-Lymphocytes activate by encountering their specific antigen

either: 1) on a host cell that has either: 1) on a host cell that has been invaded by a pathogen e.g. (virus), 2) macrophage that been invaded by a pathogen e.g. (virus), 2) macrophage that has performed antigen presentation or, 3) pathogen has performed antigen presentation or, 3) pathogen laying on a host cell. laying on a host cell.

They divide by mitosis & develop into: They divide by mitosis & develop into: 1) T-helper cells (Th) & 2) T-cytotoxic (Tc) cells. 1) T-helper cells (Th) & 2) T-cytotoxic (Tc) cells. Which in turn, form clones of memory cells [for faster Which in turn, form clones of memory cells [for faster 2ry immune response] & clones of their own type of cells with 2ry immune response] & clones of their own type of cells with a specific function. i.e. (Th)cells secrete cytokines which a specific function. i.e. (Th)cells secrete cytokines which stimulate: 1) microphage [to eliminate pathogens more stimulate: 1) microphage [to eliminate pathogens more vigorously] & 2) appropriate type of B-cells to form clones of vigorously] & 2) appropriate type of B-cells to form clones of plasma cells [to release antibodies] .plasma cells [to release antibodies] .

B-LymphocytesB-Lymphocytes

1.1.(Th) cells secrete cytokines, which stimulate (Th) cells secrete cytokines, which stimulate the appropriate type of B-Lymphocyte cells, the appropriate type of B-Lymphocyte cells, to:to:

1.1.Form clone of [plasma cells] that synthesize Form clone of [plasma cells] that synthesize and produce antibodies which are and produce antibodies which are complementary to the pathogencomplementary to the pathogen’’s antigen & s antigen & mark it for itmark it for it’’s recognition by neutrophils to s recognition by neutrophils to manipulate phagocytosis. manipulate phagocytosis.

2.2.Form clone of [memory cells], which have an Form clone of [memory cells], which have an antibody complementary to the pathogenantibody complementary to the pathogen’’s s antigen for faster 2ry immune response.antigen for faster 2ry immune response.

What happens What happens during 2nd immune during 2nd immune response?response?

Memory Cells patrol the body cells via blood.Memory Cells patrol the body cells via blood.

They recognize a foreign antigen with They recognize a foreign antigen with complementary shape to itcomplementary shape to it’’s protein receptor. s protein receptor.

Forms clones of [plasma cells] which secrete Forms clones of [plasma cells] which secrete antibodies. antibodies.

Forms more [memory cells] for faster 3ry Forms more [memory cells] for faster 3ry immune response.immune response.

AntiAnti--bodbodyyAn antibody is a globular protein made of 4 polypeptide An antibody is a globular protein made of 4 polypeptide

chains and forms the group of plasma cells [immunoglobulins (Ig)].chains and forms the group of plasma cells [immunoglobulins (Ig)].

It consists of two regions:It consists of two regions:

It has two functions:It has two functions:

1.1. Marks foreign antigens for phagocytosis by neutrophils.Marks foreign antigens for phagocytosis by neutrophils.

2.2. Releases antitoxins to neutralize the toxicity of pathogenic materials.Releases antitoxins to neutralize the toxicity of pathogenic materials.

**Constant region:Constant region: Binds with the antigenBinds with the antigen

**Variable region:Variable region:

Binds with phagocytes (neutrophils).Binds with phagocytes (neutrophils).OR OR

Attaches to a mast cell & triggers the release Attaches to a mast cell & triggers the release of histamine which causes inflammation.of histamine which causes inflammation.

Neutrophils Neutrophils underogoing underogoing phagocytosisphagocytosis!!!!

1.1. Become attracted to site of Become attracted to site of infection by chemotaxis due to: infection by chemotaxis due to: 1.1. chemicals produced by chemicals produced by

pathogens in addition to, pathogens in addition to,

2.2. ““HistamineHistamine”” (produced by (produced by most cells, to leak capillaries, most cells, to leak capillaries, cause inflammation & allow cause inflammation & allow neutrophils to squeeze out of neutrophils to squeeze out of plasma & into the tissues).plasma & into the tissues).

1.1.Engulfs (intakes) Engulfs (intakes) pathogens by pathogens by ““EndocytosisEndocytosis””..

2.2.Packs the pathogens Packs the pathogens in a in a phagocytic phagocytic vesiclevesicle (Phagosome). (Phagosome).

3.3.1ry Lysosomes fuse 1ry Lysosomes fuse with the phagosome with the phagosome to generate the 2ry to generate the 2ry lysosomes & lysosomes & ““Phago-Phago-lyso-somelyso-some””. .

4.4.Lysosomes secrete Lysosomes secrete hydrolytic enzymes, hydrolytic enzymes, which digest the which digest the pathogens. pathogens.

Immune system Immune system DysfunctionDysfunction

*Under-reaction*Under-reaction

CancerCancer InfectionsInfections

*Over-reaction*Over-reaction

Auto-immune Auto-immune problemproblem AllergyAllergy

Maybe caused byMaybe caused by::•StressStress•Environmental factorsEnvironmental factors•Drugs Drugs •Lack of sleepLack of sleep•Unbalanced dietUnbalanced diet

Brief Brief Illustration.. Illustration..

WBCs are made by stem cells at the bone WBCs are made by stem cells at the bone marrow.marrow.

*Phagocytes*Phagocytes *Lymphocytes*Lymphocytes

1) 1) MacrophageMacrophage

Antigen PresentationAntigen Presentation(Largest)(Largest)

4) Neutrophils4) NeutrophilsPhagocytosisPhagocytosis

(Large)(Large)

2) T-cells2) T-cellsActivates, then forms clones of Th Activates, then forms clones of Th

& Tc. & Tc. ThTh: releases cytokines that : releases cytokines that

stimulate appropriate type of B-stimulate appropriate type of B-cells to form clones & cells to form clones &

macrophages to operate more macrophages to operate more vigorously.vigorously.

TcTc: eliminates infected & : eliminates infected & cancerous cells displaying foreign cancerous cells displaying foreign

antigenantigen(recognize-attach-punch holes-(recognize-attach-punch holes-

secrete toxic (H2O2)).secrete toxic (H2O2)).Memory T-cellsMemory T-cells: activate quickly : activate quickly

during 2ry immune response.during 2ry immune response.

3) B-cells3) B-cellsForms clones of memory & Forms clones of memory &

plasma cells (Ig).plasma cells (Ig).MemoryMemory: Quick immune : Quick immune

response to antigens that are response to antigens that are recognized as having entered recognized as having entered

the body before.the body before.PlasmaPlasma: releases antibodies.: releases antibodies.Antibody: marks antigen & Antibody: marks antigen &

secretes secretes ““antitoxinsantitoxins””

Released from bone Released from bone marrow into blood as marrow into blood as monocytes then, mature monocytes then, mature at different organs such at different organs such as: Lungs, liver, spleen & as: Lungs, liver, spleen & lymph nodes.lymph nodes.

(Long-lived)(Long-lived)

During infection, they are During infection, they are attracted via chemotaxis attracted via chemotaxis to infected tissue by: to infected tissue by: histamine (form mast histamine (form mast cells) & pathogenic cells) & pathogenic chemicals. chemicals.

(Short-lived)(Short-lived)

+Made at the bone +Made at the bone marrow &marrow &+Mature at the thymus +Mature at the thymus gland. +Each TCR is gland. +Each TCR is complementary to a complementary to a specific antigen, but specific antigen, but similar to the antibody.similar to the antibody.

After they mature, B-cells After they mature, B-cells spread throughout body, spread throughout body, +but conc. in: Lymph nodes +but conc. in: Lymph nodes & spleen.& spleen.+Antibodies are secreted +Antibodies are secreted into: blood, lymph & onto into: blood, lymph & onto lining of lungs & guts. lining of lungs & guts. +They run down due to: +They run down due to: phagocytosis & urination.phagocytosis & urination.

Figural embodiment..Figural embodiment..overviewoverview

Macrophage recognize the virusMacrophage recognize the virus’’s antigens antigen

T-cells trigger the T-cells trigger the proliferation of plasma proliferation of plasma cellscells

Macrophage trigger the t-cellsMacrophage trigger the t-cells

T-cells trigger the correct type of T-cells trigger the correct type of B-cells to get activated and B-cells to get activated and initiate the proliferation of pasma initiate the proliferation of pasma cellscells

Plasma cells release Plasma cells release antibodiesantibodies

Antibodies contain antigen binding sites which Antibodies contain antigen binding sites which bind to the foreign body and mark it to be bind to the foreign body and mark it to be engulfed and hydrolysed by macrophagesengulfed and hydrolysed by macrophages ’’ hydrolytic enzymeshydrolytic enzymes’’ activity activity

SummarySummary

Have a safe and immunized Have a safe and immunized life...life...