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10.SISTEM IMUN TIANA MILANDA

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10.SISTEM IMUN

TIANA MILANDA

SISTEM IMUN

Kekebalan/imunitas : resistensi suatu organisme

terhadap infeksi mikroba patogen tertentu

Sistem imun : mekanisme pertahanan diri suatu

organisme (sel inang) terhadap infeksi

Dasar imunitas : kemampuan sistem imun untuk

mengenali substansi asing/antigen (sel hewan, virus,

bakteri, toksin, toksoid, vaksin, dll) dari sel/

substansi sel inang

ANTIGEN

Antigen : suatu bahan asing yang dapatmenimbulkan respon imun.

Semakin asing komposisi atau struktur kimia suatuantigen, semakin menginduksi respon imun.

Antigen umumnya bahan dengan BM tinggi. Ada 2 senyawa alami antigenik :

1. Protein lebih efektif

2. Polisakarida, terutama polisakarida

kompleks berukuran besar, contoh : kapsul

bakteri

ANTIGEN

Antigen dapat berupa :

1. Bahan yang larut dalam air: toksin bakteri, toksoid

atau protein serum

2. Partikulat : sel hewan, virus, atau bakteri lebih

efektif

Antigen-

binding

sitesAntibody A

Antigen

Antibody BAntibody C

Epitopes

(antigenic

determinants)

Determinan antigen/epitop :

situs reaktif pada

permukaan atau bagian

dalam antigen yang

berikatan dengan antibodi

menentukan kespesifikan

respon imun

ANTIGEN

Jumlah epitop per antigen : sekitar 2-3, ada yg sampai

200

Bentuk epitop antigen biasanya spesifik untuk spesies

tertentu

Antigen heterogenetik/heterofil : kelompok antigen

yang terdapat pada spesies-spesies yang berbeda

Contoh : antigen Forssman pada sel darah merah

marmot, kuda, sapi, kucing, ayam dan beberapa bakteri

menginduksi antibodi yang sama/mirip

HAPTEN

Hapten : bahan-bahan yang tidak bersifat

antigenik, tetapi bila bergabung dengan molekul

antigen seperti protein, dapat berfungsi sebagai

epitop antigen

Contoh : oligosakarida, lemak dan asam nukleat

AJUVAN

Ajuvan : bahan yang ditambahkan pada antigen untuk

merangsang pembentukan antibodi,

Contoh :

- Alum dan garam-garam alumunium lainnya

- Natrium alginat

- Endotoksin bakteri

- Suspensi air-minyak dengan/tanpa mikroba

patogen yang telah dilemahkan/dimatikan, contoh :

ajuvan Freund yang berisi minyak mineral, zat

pengemulsi dan suspensi M. tuberculosis

SUMBER ANTIGEN

Antigen alami :

Antigen jaringan manusia : antigen pada sel

darah dan jaringan

Antigen bakteri dan virus

Antigen hewan dan tumbuhan

Antigen buatan :

Vaksin

Toksoid

ANTIGEN PADA SEL DARAH

Antigen pada sel darah manusia : antigen A, B, Rh, MN, Ss, P,

dll.

Antigen A dan B digunakan untuk penggolongan darah

berdasarkan reaksi isoantibodi

ANTIGEN PADA SEL DARAH

Transfusion with incompatible blood :leads to

destruction of the transfused cells can be fatal

Another red blood cell antigen, the Rh factor

Creates difficulties when an Rh-negative

mother carries successive Rh-positive fetuses

erytroblastosis fetalis

ANTIGEN PADA JARINGAN

The immune system’s ability to distinguish self from

nonself tissue transplantation

Transplanted tissues are usually destroyed by the

recipient’s immune system

MHC (major histocompatibility complex) molecules

are responsible for stimulating the rejection of tissue

grafts and organ transplants

The chances of successful transplantation are

increased :

If the donor and recipient MHC tissue types are

well matched

If the recipient is given immunosuppressive drugs

ANTIGEN PADA BAKTERI

Antigen bakteri terdiri dari komponen struktural sel, eksotoksin dan enzim

Komponen struktural sel :

1.1. Kapsul : kapsul pada pneumokokus, antigen kapsular

2. K atau Vi pada Salmonella typhi

3.2. Flagel : antigen H pada Salmonella typhi

4.3. Endotoksin : kompleks polisakarida-fosflipid-protein,

5. seperti antigen O pada Salmonella typhi.

6.

Struktur antigen digunakan sebagai dasar klasifikasi suatubakteri

ANTIGEN ALAMI LAINNYA

Antigen pada struktur terluar virus yang terdiri

dari protein, lipoprotein atau glikoprotein

Antigen hewan dan tumbuhan dapat berbahaya

bagi kesehatan.

Contoh : antigen regweed (sejenis rumput-

rumputan) yang menyebabkan hay fever

ANTIGEN BUATAN

Vaksin :

- suspensi mikroba hidup yang dilemahkan (contoh :

vaksin poliomielitis Sabin) atau

- mikroba mati (contoh : vaksin demam tifoid,

vaksin poliomielitis Salk) atau

- produk-produknya (contoh : toksin bakteri)

- bagian dari selnya (contoh : fragmen struktur terluar

virus hepatitis B vaksin hepatitis B)

yang dapat menimbulkan kekebalan sel inang terhadap

infeksi mikroba tersebut

Toksoid : toksin yang telah dirusak, tanpa mengubah

antigenisitasnya menghasilkan antibodi antitoksin

TIPE SISTEM IMUN

Imunitas non spesifik/alamiah (innate immunity)

Is present before any exposure to pathogens

and is effective from the time of birth

Involves nonspecific responses to pathogens

Imunitas spesifik/dapatan (acquired/adaptive

immunity)

Develops only after exposure to inducing agents

such as microbes, toxins, or other foreign

substances

Involves a very specific response to pathogens

Innate and acquired immunity

INNATE IMMUNITY

Rapid responses to a

broad range of microbes

ACQUIRED IMMUNITY

Slower responses to

specific microbes

External defenses Internal defenses

Skin

Mucous membranes

Secretions

Phagocytic cells

Antimicrobial proteins

Inflammatory response

Natural killer cells

Humoral response

(antibodies)

Cell-mediated response

(cytotoxic

lymphocytes)

Invading

microbes

(pathogens)

Innate immunity

Innate immunity provides broad defenses against

infection : external and internal defenses

External defenses

Intact skin and mucous membranes

Form physical barriers that bar the entry of

microorganisms and viruses

Certain cells of the mucous membranes produce

mucus

A viscous fluid that traps microbes and other

particles

Innate immunity

In the trachea, ciliated epithelial cells

Sweep mucus and any entrapped microbes upward,

preventing the microbes from entering the lungs

Secretions from the skin

Give the skin a pH between 3 and 5, which is acidic

enough to prevent colonization of many microbes

Also include proteins such as lysozyme, an enzyme

that digests the cell walls of many bacteria

External

Defenses

Internal Defenses

Internal defenses :

1. Phagocytic cells

2. Antimicrobial proteins

3. Inflammantory respons

4. Natural killer cells

Homeopoietic system

Leukosit

Granulosit :

Neutrofil : pertahanan tubuh terhadap infeksi bakteri serta

proses peradangan kecil melalui fagositosis. Aktivitas dan

matinya neutrofil dalam jumlah besar menyebabkan nanah.

Eosinofil : pertahanan tubuh terhadap infeksi parasit.

Basofil dan mast cell bertanggung jawab terhadap reaksi

alergi dengan mengeluarkan histamin yang menyebabkan

peradangan.

Monosit membagi fungsi fagositosis dengan neutrofil.

Monosit dikenal sebagai makrofag, setelah meninggalkan

aliran darah serta masuk ke dalam jaringan.

Sel natural killer: sel yang dapat membunuh sel tubuh yang

telah terinfeksi virus atau telah berubah sel kanker.

Leukosit

Agranulosit :

Sel B: membuat antibodi yang akan berikatan dengan

antigen utuh, lalu menghancurkannya. Sel B

menghasilkan sel memori

Sel T: terdiri dari dari sel T helper dan sel T sitotoksik.

Kedua sel T mengkoordinasi sistem imun dan

menghancurkan antigen/bakteri yang telah

menginfeksi sel.

Adenoid

Tonsil

Lymph

nodes

Spleen

Peyer’s patches

(small intestine)

Appendix

Lymphatic

vesselsMasses of

lymphocytes and

macrophages

Tissue

cells

Lymphatic

vessel

Blood

capillary

Lymphatic

capillaryInterstitial

fluid

Lymph

node

The lymphatic system

Macrophages, can be found migrating through the body and in various

organs of the lymphatic systemInterstitial fluid bathing the

tissues, along with the white

blood cells in it, continually

enters lymphatic capillaries.

1

Fluid inside the

lymphatic capillaries,

called lymph, flows

through lymphatic

vessels throughout

the body.

2

Within lymph nodes,

microbes and foreign

particles present in

the circulating lymph

encounter macro-

phages, dendritic cells,

and lymphocytes,

which carry out

various defensive

actions.

3

Lymphatic vessels

return lymph to the

blood via two large

ducts that drain into

veins near the

shoulders.

4

1. Phagocytic Cells

Phagocytes attach to

their prey via surface

receptors

And engulf them,

forming a vacuole

that fuses with a

lysosome

Pseudopodia

surround

microbes.

1

Microbes

are engulfed

into cell.

2

Vacuole

containing

microbes

forms.

3

Vacuole

and lysosome

fuse.

4

Toxic

compounds

and lysosomal

enzymes

destroy microbes.

5

Microbial

debris is

released by

exocytosis.

6

Microbes

MACROPHAGE

Vacuole Lysosome

containing

enzymes

2. Antimicrobial Proteins

Numerous proteins function in innate defense

By attacking microbes directly of by impeding

their reproduction

About 30 proteins make up the complement

system

Which can cause lysis of invading cells and help

trigger inflammation

Interferons

Provide innate defense against viruses and help

activate macrophages

3. Inflammatory Response

In local inflammation, histamine and other chemicals

released from injured cells promote changes in blood

vessels that allow more fluid, more phagocytes, and

antimicrobial proteins to enter the tissuesPathogen Pin

Macrophage

Chemical signals

CapillaryPhagocytic cells

Red blood cell

Blood

clotting

elements

Blood clot

Phagocytosis

Fluid, antimicrobial proteins,

and clotting elements move

from the blood to the site.

Clotting begins.

2Chemical signals released

by activated macrophages

and mast cells at the injury

site cause nearby capillaries

to widen and become more

permeable.

1 Chemokines released by various

kinds of cells attract more

phagocytic cells from the blood

to the injury site.

3 Neutrophils and macrophages

phagocytose pathogens and

cell debris at the site, and the

tissue heals.

4

4. Natural Killer Cells

Natural killer (NK) cells

Patrol the body and attack virus-infected body

cells and cancer cells

Trigger apoptosis in the cells they attack

Acquired immunity

In acquired immunity, lymphocytes provide

specific defenses against infection

Lymphocytes

Arise from stem cells in the bone marrow

The vertebrate body is populated by two main

types of lymphocytes

B lymphocytes/B cells

T lymphocytes/T cells

Newly formed

lymphocytes are all alike

But they later develop

into B cells or T cells,

depending on where

they continue their

maturation

Lymphocyte Development

As B and T cells are

maturing in the bone and

thymus

Bone marrow

Lymphoid

stem cell

B cell

Blood, lymph, and lymphoid tissues

(lymph nodes, spleen, and others)

T cell

Thymus

Acquired immunity

Acquired immunity includes two branches

The humoral immune response involves the

activation and clonal selection of B cells,

resulting in the production of secreted

antibodies

The cell-mediated immune response involves the

activation and clonal selection of T cells

Clonal selection : binding of antigen to a mature

lymphocyte induces the lymphocyte’s

proliferation and differentiation

The humoral immune response

Generates a clone of short-lived activated effector

cells and a clone of long-lived memory cells

Antigen molecules

Antigen

receptor

B cells that

differ in

antigen

specificity

Antibody

molecules

Clone of memory cellsClone of plasma cells

Antigen molecules

bind to the antigen

receptors of only one

of the three B cells

shown.

The selected B cell

proliferates, forming

a clone of identical

cells bearing

receptors for the

selecting antigen.

Some proliferating

cells develop into

short-lived plasma

cells that secrete

antibodies specific

for the antigen.

Some proliferating cells

develop into long-lived

memory cells that can

respond rapidly upon

subsequent exposure

to the same antigen.

In the secondary immune response

Memory cells facilitate a faster, more efficient

responseA

ntib

ody c

on

ce

ntr

ation

(arb

itra

ry u

nits)

104

103

102

101

100

0 7 14 21 28 35 42 49 56

Time (days)

Antibodies

to AAntibodies

to B

Primary

response to

antigen A

produces anti-

bodies to A

2Day 1: First

exposure to

antigen A

1 Day 28:

Second exposure

to antigen A; first

exposure to

antigen B

3 Secondary response to anti-

gen A produces antibodies

to A; primary response to anti-

gen B produces antibodies to B

4

B Cell Receptors for Antigens

B cell receptors

Bind to specific, intact antigens

Are often called membrane antibodies or

membrane immunoglobulin (Ig)

Antibodi : substansi khusus yang dibentuk sel B

sebagai respon terhadap antigen

ANTIBODI

Antigen-

binding

site

Antigen-

binding siteDisulfide

bridge

Light

chain

Heavy chains

Cytoplasm of B cell

A B cell receptor consists of two identical heavy

chains and two identical light chains linked by

several disulfide bridges.

(a)

Variable

regions

Constant

regions

Transmembrane

region

Plasma

membrane

B cell

C C

Struktur imunoglobulin terdiri dari unit monomer yang terdiri

dari 2 rantai polipeptida ringan (sekitar 25.000 dalton) dan 2

rantai polipeptida berat (sekitar 50.000 dalton)yang

dihubungkan dengan ikatan sulfida

DNA of

undifferentiated

B cell

DNA of differentiated

B cell

pre-mRNA

mRNA Cap

B cell

B cell receptorLight-chain polypeptide

Intron

Intron

Intron

Variable

regionConstant

region

V1 V2 V3

V4–V39

V40 J1 J2 J3 J4 J5

V1 V2 V3 J5

V3 J5

V3 J5

V C

C

C

C

C

Poly (A)

Deletion of DNA between a V segment

and J segment and joining of the segments1

Immunoglobulin gene rearrangement

Transcription of resulting permanently rearranged,

functional gene2

RNA processing (removal of intron; addition of cap

and poly (A) tail)3

4 Translation

JENIS ANTIBODI

Berdasarkan urutan asam amino

dalam rantai beratnya, antibodi

terbagi menjadi :

1. Imunoglobulin G (IgG)

tipe (gamma)

2. Imunoglobulin M (IgM)

tipe (mui)

3. Imunoglobulin A (IgA)

tipe (alfa)

4. Imunoglobulin D (IgD)

tipe (delta)

5. Imunoglobulin E (IgE)

First Ig class produced after initial exposure to

antigen; then its concentration in the blood declines

Most abundant Ig class in blood; also present in

tissue fluids

Only Ig class that crosses placenta, thus conferring

passive immunity on fetus

Promotes opsonization, neutralization, and agglutination

of antigens; less effective in complement activation than

IgM (see Figure 43.19)

Present in secretions such as tears, saliva, mucus,

and breast milk

Triggers release from mast cells and basophils of

histamine and other chemicals that cause allergic

reactions (see Figure 43.20)

Present primarily on surface of naive B cells that have

not been exposed to antigens

IgM

(pentamer)

IgG

(monomer)

IgA

(dimer)

IgE

(monomer)

J chain

Secretory

component

J chain

Transmembrane

region

IgD

(monomer)

Promotes neutralization and agglutination of

antigens; very effective in complement activation

(see Figure 43.19)

Provides localized defense of mucous membranes by

agglutination and neutralization of antigens (see

Figure 43.19)

Presence in breast milk confers passive immunity on

nursing infant

Acts as antigen receptor in antigen-stimulated

proliferation and differentiation of B cells (clonal

selection)

IgG

- 70-80 % dari Ig total

- IgG terbagi menjadi 4 sub kelas IgG1

(59%), IgG2 (30%), IgG3 (8%) dan IgG4

(3%), semuanya berbentuk monomer.

- IgG diwariskan ibu ke janin melalui

plasenta dan kolostrum .

- Fungsi IgG : pertahanan diri utama

pada bbrp minggu pertama setelah

kelahiran, pertahanan diri setelah IgM

IgM

- 6 % dari Ig total

- Makroglobulin berukuran 5 kali lebih besar

dari IgG, karena terdiri dari 5 unit

monomer dengan suatu peptida tambahan

(rantai J berfungsi menstabilkan

struktur IgM.

- Adanya 5 monomer membuat ikatan IgM-

antigen lebih dari 1 situs, sehingga

efektif thd bakteri/virus.

- Situs IgM : sebagian besar pada aliran

darah

- Fungsi IgM: merupakan antigen pertama

yang muncul setelah stimulasi antigen.

IgA

- 10% dari Ig total

- Struktur dasar : 2 rantai berat dan 2 rantai ringan

dalam bentuk polimer (sebagian besar dimer,

sebagian kecil trimer) melalui ikatan disulfida.

- Situs IgA : serum, sekresi tubuh eksternal (air mata,

air liur, air mani, air seni dan kolostrum, dan sekresi

di selaput lendir paru-paru dan usus

- Fungsi IgA : perlindungan utama pada

bayi yang baru lahir, melindungi mukosa

dan permukaan luar tubuh

IgD Function not fully

understood

Found on B-cell surface

during different stages of

maturation

Possible involvement in

cell differentiation

IgE

Most IgE bound to IgE

receptor on mast cells

Antigen binding to IgE

releases inflammatory

substances

Histamine

Pathogenesis of hay fever,

allergic asthma

The allergic response

IgE antibodies produced in response to initial exposure to an allergen bind to receptors or mast cells.

1 On subsequent exposure to the same allergen, IgE molecules attached to a mast cell recog-nize and bind the allergen.

2 Degranulation of the cell,triggered by cross-linking of adjacent IgE molecules, releases histamine and other chemicals, leading to allergysymptoms.

3

1

2

3

Allergen

IgE

Histamine

Granule

Mast cell

NAMA FUNGSIONAL ANTIBODI

Pemberian nama antibodi menggambarkan reaksi in vitro/in vivo antibodi dengan antigen, yaitu :

1. Antitoksin : menetralkan toksin

2. Opsonin : membuat mikroba lebih peka

terhadap fagositosis

3. Aglutinin : menggumpalkan antigen

4. Presipitin : pengendapan/flokulasi antigen

5. Antibodi pengikat komplemen : penambatan

/fiksasi komplemen (protein antimikrobal)

6. Lisin : lisis/penguraian antigen

Jika multifungsi, antibodi dapat diberi beberapanama

Antibody-mediated mechanisms of

antigen disposalBinding of antibodies to antigens

inactivates antigens by

Viral neutralization

(blocks binding to host)

and opsonization (increases

phagocytosis)

Agglutination of

antigen-bearing particles,

such as microbes

Precipitation of

soluble antigens

Activation of complement system

and pore formation

Bacterium

Virus Bacteria

Soluble

antigens Foreign cell

Complement

proteinsMAC

Pore

Enhances

Phagocytosis

Leads to

Cell lysis

Macrophage

Acquired immunity

Acquired immunity includes two branches

The humoral immune response involves the

activation and clonal selection of B cells,

resulting in the production of secreted

antibodies

The cell-mediated immune response involves the

activation and clonal selection of T cells

Clonal selection : binding of antigen to a mature

lymphocyte induces the lymphocyte’s

proliferation and differentiation

Antigen-

Binding site

chain

Disulfide bridge

chain

T cell

A T cell receptor consists of one

chain and one chain linked by

a disulfide bridge.

(b)

Variable

regions

Constant

regions

Transmembrane

region

Plasma

membrane

Cytoplasm of T cell

T Cell Receptors for Antigens

Each T cell receptor

Consists of two different

polypeptide chains

T cells bind to small

fragments of antigens

That are bound to normal

cell-surface proteins

called MHC (major

histocompatibility

complex) molecules

V

C

MHC molecules

Infected cells produce MHC molecules

Which bind to antigen fragments and then are

transported to the cell surface in a process

called antigen presentation

A nearby T cell

Can then detect the antigen fragment

displayed on the cell’s surface

Depending on their source

Peptide antigens are handled by different

classes of MHC molecules

Class I MHC molecules

Infected cell

Antigen

fragment

Class I MHC

molecule

T cell

receptor

(a) Cytotoxic T cell

A fragment of

foreign protein

(antigen) inside the

cell associates with

an MHC molecule

and is transported

to the cell surface.

1

The combination of

MHC molecule and

antigen is recognized

by a T cell, alerting it

to the infection.

2

1

2

Found on almost all nucleated cells of the body

Display peptide

antigens to

cytotoxic T cells

Cytotoxic T cell

Perforin

Granzymes

CD8TCR

Class I MHC

molecule

Target

cell Peptide

antigen

Pore

Released

cytotoxic

T cell

Apoptotic

target cell

Cancer

cell

Cytotoxic

T cell

A specific cytotoxic T cell binds to a

class I MHC–antigen complex on a

target cell via its TCR with the aid of

CD8. This interaction, along with

cytokines from helper T cells, leads to

the activation of the cytotoxic cell.

1 The activated T cell releases perforin

molecules, which form pores in the

target cell membrane, and proteolytic

enzymes (granzymes), which enter the

target cell by endocytosis.

2 The granzymes initiate apoptosis within the

target cells, leading to fragmentation of the

nucleus, release of small apoptotic bodies,

and eventual cell death. The released

cytotoxic T cell can attack other target cells.

3

1

2

3

The activated cytotoxic T cell

Secretes proteins that destroy the infected target

cell

Class II MHC molecules

Located mainly on dendritic cells,

macrophages, and B cells

Display antigens

to helper T cells

1

2

Microbe Antigen-

presenting

cell

Antigen

fragment

Class II MHC

molecule

T cell

receptor

Helper T cell

A fragment of

foreign protein

(antigen) inside the

cell associates with

an MHC molecule

and is transported

to the cell surface.

1

The combination of

MHC molecule and

antigen is recognized

by a helper T cell, alerting it

to the infection.

2

(b)

The role of helper T cells

in acquired immunity

After a dendritic cell engulfs and degrades a bacterium, it displays

bacterial antigen fragments (peptides) complexed with a class II

MHC molecule on the cell surface. A specific helper T cell binds

to the displayed complex via its TCR with the aid of CD4. This

interaction promotes secretion of cytokines by the dendritic cell.

Proliferation of the T cell, stimulated

by cytokines from both the dendritic

cell and the T cell itself, gives rise to

a clone of activated helper T cells

(not shown), all with receptors for the

same MHC–antigen complex.

The cells in this clone

secrete other cytokines

that help activate B cells

and cytotoxic T cells.

Cell-mediated

immunity

(attack on

infected cells)

Humoral

immunity

(secretion of

antibodies by

plasma cells)

Dendritic

cell

Dendritic

cell

Bacterium

Peptide antigen

Class II MHC

molecule

TCR

CD4

Helper T cell

Cytokines

Cytotoxic T cell

B cell

1

2 3

1

2 3

B Cells: A Response to Extracellular

Pathogens

2

13

B cell

Bacterium

Peptide

antigen

Class II

MHC

molecule

TCR

Helper T cell

CD4

Activated

helper T cell Clone of memory

B cells

Cytokines

Clone of plasma cellsSecreted antibody

molecules

Endoplasmic

reticulum of

plasma cell

Macrophage

After a macrophage engulfs and degrades

a bacterium, it displays a peptide antigen

complexed with a class II MHC molecule.

A helper T cell that recognizes the displayed

complex is activated with the aid of cytokines

secreted from the macrophage, forming a

clone of activated helper T cells (not shown).

1 A B cell that has taken up and degraded the

same bacterium displays class II MHC–peptide

antigen complexes. An activated helper T cell

bearing receptors specific for the displayed

antigen binds to the B cell. This interaction,

with the aid of cytokines from the T cell,

activates the B cell.

2 The activated B cell proliferates

and differentiates into memory

B cells and antibody-secreting

plasma cells. The secreted

antibodies are specific for the

same bacterial antigen that

initiated the response.

3

The roles of the major participants in the

acquired immune response

Humoral immune response Cell-mediated immune response

First exposure to antigen

Intact antigensAntigens engulfed and

displayed by dendritic cells

Antigens displayed

by infected cells

Activate Activate Activate

Gives rise to Gives rise to Gives rise to

B cellHelper

T cellCytotoxic

T cell

Plasma

cells

Memory

B cells

Active and

memory

helper

T cells

Memory

cytotoxic

T cells

Active

cytotoxic

T cells

Secrete antibodies that defend against

pathogens and toxins in extracellular fluid

Defend against infected cells, cancer

cells, and transplanted tissues

Secreted

cytokines

activate

Autoimmune Diseases

In individuals with autoimmune diseases

The immune system loses tolerance for self and turns

against certain molecules of the body

Rheumatoid arthritis

Is an autoimmune disease that leads

to damage and painful inflammation

of the cartilage and bone of joints

• Other examples of autoimmune diseases include

- Systemic lupus erythematosus

- Multiple sclerosis

- Insulin-dependent diabetes

Immunodeficiency Diseases

An inborn or primary immunodeficiency

Results from hereditary or congenital defects that

prevent proper functioning of innate, humoral, and/or

cell-mediated defenses

In severe combined immunodeficiency (SCID)

Both the humoral and cell-mediated branches of

acquired immunity fail to function

An acquired or secondary immunodeficiency

Results from exposure to various chemical and

biological agents

Range from temporary states to chronic diseases

That physical and emotional stress can harm immunity

Acquired Immunodeficiency

Syndrome (AIDS)People with AIDS

Are highly susceptible to opportunistic infections

and cancers that take advantage of an immune

system in collapse

Because AIDS arises from the loss of helper T cells

Both humoral and cell-mediated

immune responses are impaired

The loss of helper T cells

Results from infection by the

human immunodeficiency virus (HIV)1µm