immunology easy notes

7/23/2019 Immunology Easy Notes

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IMMUNOLOGY

ADAPTIVE AND INNATE IMMUNITY

ADAPTIVE IMMUNITY - highly specifc or a certain pathogen

- response improves with each successive encounters- remembers and prevents an inectious agent that had already been

encountered- 2 key eatures are specifcity and memory.

INNATE IMMUNITY

- Non-specifc- Same response ater repeated exposure- Has no memory

ELL! O" T#E IMMUNE !Y!TEM

- All cells o the immune system arise rom pluripotent stem cellsthrough two main line o dierentiation! "# the $ymp%oid $inea&e$produces lymphocytes#% 2# the mye$oid $inea&e $producesphagocytes and other cells#

&' P#AGOYTI ELL!' P#AGOYTE!' ANTIGEN-P(E!ENTINGELL! )AP*

- monocytes( macrophages( )*Ns- enguls pathogens( internali+es them and destroys them

within the cell- uses non-specifc recognition systems- mediate innate immunity

- considered the frst cellular line o deense

A' MONONULEA( ELL!' MONOYTE!- ,erived rom the bone marrow stem cells- unction is to engul particles( internali+e them and

destroy them- .ective in presentin& anti&ens to T

$ymp%ocytes- /ong-lived phagocytic cells

0' PMN!) POLYMO(P#ONULEA( !EGMENTE(!*'NEUT(OP#IL

- 1onstitutes the maority o blood leukocytes- !%ort-$i+ed p%a&ocytic ce$$s $ater internali+ing

and destroying pathogens( they die#-

&&' LYMP#OYTE!- 1entral cells in adaptive immunity' )roduced at a rate o

"345 per day'



- 6he adult constitutes about "34"2 lymphoid cells( and thelymphoid tissue as a whole is about 27 o the total bodyweight'

- 1an recogni+e individual pathogens whether inside oroutside o host cells

- Specifc immune recognition- ,erived rom the bone marrow stem cells( although the 6lymphocytes develop urther in the thymus $the bonemarrow and thymus are considered the primarylymphoid organs.#

D MA(,E(' LU!TE( O" DI""E(ENTIATION- 8eers to groups o monoclonal antibodies( each cluster

binding specifcally to a particular cell marker- ,epends on computer analysis o monoclonal antibodies

produced mainly in mice against human leukocyte

antigens'- .xample is D also known as the common leukocyte

antigen

A' / ELL! )/ 0 /U(!A1 23rsa o4 4a2rici3s in c%ic5ens*- D MA(,E(6

D78 9 main marker to identiy 0 cells'

D:; 9 main marker to identiy 0 cells'

D:7 9 also known as 182( which is the

complement receptor or 19d' 1ommonly oundin 0 cells' Associated with homing o cells'

D:: 9 main marker to identiy 0 cells' D< 9 also known as 18"( which is the

complement receptor or 19b' 1ommonly oundin 0 cells' Associated with homing o cells'

D<: 9 c receptors or exogenous &g:( which

play a role in negative signalling to 0 cells' D=: 9 ligand o 1,; in 6 cells'

- 8epresents ;-";7 o circulating lymphoid pool( andare classically defned by the presence o suraceimmunoglobulins( seen with <uorochrome-labelledantibodies specifc or the immunoglobulins resultingin a =ring-like> pattern $when cold# or cap-like $whenwarm# pattern'

- 6he main immunoglobulin seen on their surace are&g* and &g,

- Specifcally recogni+es a particular antigen using areceptor molecule on its surace

- ,evelops in the 4eta$ $i+er or ad3$t 2one marro>.



- 0 cells are occasionally seen with a de+e$opin&ro3&% endop$asmic retic3$3m'

- 1ombats e?trace$$3$ar pat%o&ens by release oanti2odies( that bind to a particular target moleculecalled anti&en

- ,ivide and dierentiate into p$asma ce$$s( whichproduce large amounts o receptor molecule insoluble orm which are also otherwise known asantibodies

♦ ANTI/ODIE! 9 large glycoproteins ound in

blood and tissue <uid that unction primarily tobind to antigens( to initiate an immuneresponse against that specifc antigen' &t canalso act to activate other parts o the immunesystem' &t is produced by p$asma ce$$s.

0' T LYMPOYTE!) T 0 T#YMU!1 >%ere t%ey de+e$op*

- D MA(,E(6 D7 ? maturation marker or 6 cells1 on$y

4o3nd in ce$$s de+e$opin& in t%e t%ym3s(and is not present in circulating 6 cells

D: ? ability o 6 cells to bind to sheep

erythrocytes also known as rosette4ormation'

D< 9 e?c$3si+e 4or T ce$$s( and is involved

in cell triggering' D 9 marker or T %e$per ce$$s

D 9 ligand o 1,@2 in 0 cells'

D@ 9 marker 4or T cytoto?ic ce$$s or Ts3ppressor ce$$s

D: 9 activation marker or 6 cells( also

known as the 6 cell growth actor receptor orIL: receptor.

- &nvolved in the control o 0 lymphocyte developmentand production

- 6 helper and 6 cytotoxic cells are smaller( non-granular and with high N!1 ratio' 6hey also carry astructure called a =Ga$$ /ody>( which consists o a

c$3ster o4 primary $ysoymes( seen incytochemistry'- &nteracts with phagocytic cells and helps them

destroy pathogens- 8ecogni+es inected cells by viruses and destroys

them- ses the T() T ELL (EEPTO(* to recogni+e

antigens'



- Has the ability to release cytokines 1A6.:B8&.S B 6 1.//S!

"' T #ELPE( ELL )DB ELL!*- )ositively in<uence the response o

6 and 0 cells

- Helper cell unction which isD:8B

- 2 6C).S B 6 H./).8 1.//!a# T#7 ? mediate several

unctions related tocytotoxicity and localin<ammatory reactions' 6hese are important incombating intracellularpathogens' &t produces &/2and &N gamma'

b# T#: ? more eective instimulating 0 cells toprolierate and produceantibodies'( and unctionthereore to protect againstree living microorganisms'

2' T YTOTOCI ELL )D@B ELL!*9' T(-7B T ELL!

- *inor subpopulation o 6 cells thatare ound in mucosal suraces'

1' LA(GE G(ANULA( LYMP#OYTE! )LGLs*' N, ELL

)NATU(AL ,ILLE(*- D MA(,E(6

D= 9 ound in almost all o ND cells'

D7 9 monoclonal antibodies used to identiy

ND cells( also involved in the activation o NDpathway'

D 9 defnitive marker o ND cells'

- Accounts or ";7 o blood lymphocytes( and can benegatively defned as lymphocytes having noconventional surace antigen'

- 8ecogni+es surace changes in tumour cells and

virally inected cells- 1an be distinguished rom the 6 and 0 cells( by their

ability( in vitro( to $yse t3mo3r ce$$ $ines >it%o3tprior sensitiation.

- ses a non-specifc recognition system- ,oes not express antigen receptors- Has the ability( ANTI/ODY-DEPENDENT ELLULA(

YTOTOCIITY )AD*.



- &t is neit%er a T $ymp%ocyte nor / $ymp%ocyte.

LYMP#OYTE ATIVATION- 0oth 6 and 0 cells utili+e a :6)-dependent component $or :-protein#

to induce signalling reactions' 6hese :-proteins stimulate

phosphatidylinositol metabolism( at the same time a number osurace receptors or cytokines such as &/2 are produced'

&&&' OT#E( IMPO(TANT ELL! O" T#E IMMUNE !Y!TEM

A' EO!INOP#IL! )EO!IN 0 (ED 0 AIDOP#ILI*- Has the ability to engage and damage extracellular

parasites0' AUCILLA(Y ELL!

- &nvolved in the development o immune response by

the production and release o mediatorsa# Mast e$$s 9 cells that lie close to the blood

vessels in all tissues' &t unctions inhypersensitivity reactions

b# /asop%i$s 9 cells in the blood circulation thatunction similarly to the mast cells

c# P$ate$ets 9 attracts leukocytes to site o inury

!OLU/LE MEDIATO(! O" IMMUNITY I. AUTE P#A!E P(OTEIN!

- )roteins produced by the $i+er that are increased

rapidly during inectionA' (P' -(EATIVE P(OTEIN

- Name comes rom the ability to bind with the 1protein o pneumococci

&&' OMPLEMENT- D MA(,E(6

D:7 9 also known as 182( which is the

complement receptor or 19d' 1ommonly oundin 0 cells'

D< 9 also known as 18"( which is the

complement receptor or 19b' 1ommonly ound

in 0 cells- :roup o 23 serum proteins that control in<ammation

♦ :enerates the ollowing eects!"' Bpsoni+ation2' 1hemotaxis9' &ncreased blood <ow and permeability o

capillaries



E' ,amages plasma membranes o cells(gram $-# bacteria( and enveloped viruses

♦ 2 *AFB8 )A6HGACS B 1B*)/.*.N6

A16&A6&BN!"' LA!!IAL PAT#AY 9 initiated by

antigen-antibody reaction2' ALTE(NATIVE PAT#AY 9 initiated by

certain microorganisms&&&' YTO,INE!

- *olecules involved in the signalling between cellsA' INTE("E(ON! )I"N*

- 1onsidered the frst $ine o4 resistance to many+ir3ses'

- ,etermines how eective tissue cells interact withlymphocytes

- &nduces a state o4 anti-+ira$ resistance in

3nin4ected ce$$s- &mportant in limiting certain viral inactions

♦ 9 1A6.:B8&.S B &N6.8.8BNS!

7. I"N ALP#A:. I"N /ETA<. I"N GAMMA

I0oth &N A/)HA and 0.6A are producedby virally inected cells

/. INTE(LEU,IN! )IL*- )roduced mainly by T $ymp%ocytes( some by

mononuclear cells

- *ost are involved in directing cells to divide anddierentiate

. OLONY !TIMULATING "ATO(! )!"s*- ,irect division and dierentiation o bone marrow

stem cells- 6he balance o the dierent 1Ss partly determines

the proportion o dierent cell types which will beproduced

D. TUMO( NE(O!I! "ATO( )TN" ALP#A and TN"/ETA* and T(AN!"O(MING G(OT# "ATO( )TG"/ETA*

- &mportant in mediating in<ammation and cytotoxicreactions

.' ANTI/ODIE!- Serum molecules produced by plasma cells- Soluble orm o 0 cell antigen receptor

♦ )A86S!



"' "a2 9 part o the antibody where theantigen can be bound

2' "c 9 part that interacts with the cells othe immune system

N./. )hagocytes can recogni+e antigens using either an activated $19b# orantibody that act as opsonins( but phagocytosis is more eective i both arepresent'

Anti&en9 any molecule which can be specifcally recogni+ed by adaptive

elements

♦ )A86S B AN AN6&:.N!

"' EPITOPE 9 )art o the antigen where the antibody bindsto'

LONAL !ELETION- .ach lymphocyte is capable o recogni+ing only one particular antigen- A specifc antigen selects or the specifc clones o its own antigen-

binding cells

IMMUNE E""ETO( ME#ANI!M!A. Anti2ody /indin&

- Antibodies bind to the outer membrane o somerhinoviruses $those that cause common colds# canprevent viral paricles rom binding to host cells

/. Acti+ation o4 omp$ement 2y Anti2ody

- Antibodies in circulation can activate the classicalcomplement pathway in order to cause lysis tooreign antigens

. Anti2odies act as Opsonins- Bpsonins are antibodiesJ complement that can coat a

pathogen and make phagocytosis more eectiveD. P%a&ocytosis

- )hagocytic cells proceed to engul antigen-carryingmicrobe by extending their pseudopodia around it'the microbe is then internali+ed in a phagosome andreactive oxygen intermediates $8B&s# produced by

monocytes are toxic to bacteria( or neutrophils cansecrete transerrin which chelates iron and preventsbacteria rom acKuiring this vital nutrient( or fnallygranules rom lysosomes can use with thephagosome( pouring digestive en+ymes into thephagolysosome( digesting its contents'

E. ytoto?ic (eactions



- ,irected against >%o$e ce$$s which are too large orphagocytosis

- Attacking cells direct their granules towards thetarget cell( in contrast to phagocytosis where it isdirected against the phagosome'

- 6 cells contain molecules called perorins which canpunch holes in the outer membrane o the target- Some cytotoxic cells can signal to the target to sel-

destruct by ragmentation o ,NA or otherwiseknown as Apoptosis.

IN"LAMMATION- *aniestation o inection( wherein the body concentrates immune

products toward the site o inection' MAFO( EVENT! T#AT OU( DU(ING IN"LAMMATION

7. &ncreased blood supply to site o inection

:. &ncreased capillary permeability due to the retraction oendothelial cells' 6his permits larger molecules to escaperom capillaries and allows soluble mediators to reach thesite o inection

<. /eukocytes migrate out o the capillaries into surroundingtissues $diapedesis*'

DE"EN!E! AGAIN!T ECT(AELLULA( AND INT(AELLULA(PAT#OGEN!

- &n dealing with extracellular pathogens( the immune system aims todestroy the pathogen itsel( or neutrali+e its products'

- &n intracellular pathogens( there are two options' .ither the 6 cells candestroy the inected cell $cytotoxicity# or they can activate the cell todeal with the pathogen itsel'

VAINATION- )8&N1&)/.! based on the two key elements o adaptive immunity(

namely specifcity and memory'- 6he aim in vaccine development is to alter a pathogen or its toxins in

such a way that they become innocuous without losing theirantigenicity'

IMMUNOPAT#OLOGY - 6he immune system itsel is the cause o disease or other undesirable

conseKuences' 9 GACS B &**NB)A6HB/B:C

"' Mista5en reco&nition o4 se$4 anti&ens'AUTOIMMUNITY - 6he body reacts to not only oreign pathogens but also tohost cells



2' An ineHecti+e imm3ne response'IMMUNODE"IIENY - ,eective immune elements( unable to fght inection

9' An o+eracti+e imm3ne response' #YPE(!EN!ITIVITY - 6he immune response causes more damage than the

pathogen itsel'

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