immune system & humoral immunity
TRANSCRIPT
-
8/4/2019 Immune System & Humoral Immunity
1/55
Dr.P.S.N.RajuP.G in PhysiologyAndhra Medical CollegeVisakhapatnam
A.P , India
-
8/4/2019 Immune System & Humoral Immunity
2/55
THE IMMUNE SYSTEM
The Latin term IMMUNIS means EXEMPT, referring to
protection against foreign agents. Immunity is the ability of the bodyto specifically counteract foreign organisms or substances, called antigens.
-
8/4/2019 Immune System & Humoral Immunity
3/55
S pecific Defenses of the Host:The Immune Response
Acquired immunity Developed during anindividual's lifetime
-
8/4/2019 Immune System & Humoral Immunity
4/55
A NATOMY OF THE IMMUNE SYSTEM
-
8/4/2019 Immune System & Humoral Immunity
5/55
DEFENCECOUNTRY
ATTACKED
TWO WAYS
TO FIGHTHIRE A TRAINED FORCE - QUICK
PREPARE OWN FORCE TAKES TIME
WHICH IS BEST?
-
8/4/2019 Immune System & Humoral Immunity
6/55
ATTACK INFECTION
INFECTIONINFECTION
INFECTION
-
8/4/2019 Immune System & Humoral Immunity
7/55
DEFENCE
HIRE(PASS IVE)MAKE OWN(ACTIVE)
PHYSICAL(SKIN)
-
8/4/2019 Immune System & Humoral Immunity
8/55
Cells of Immune System
-
8/4/2019 Immune System & Humoral Immunity
9/55
Lymphocytes
Large nucleiCapable of proliferationExtensive Rough ER
Synthesize antibodies Phagocytosis
Direct killing of targetcells Modulation of the
immune response
-
8/4/2019 Immune System & Humoral Immunity
10/55
Naturally Acquired immunity.
B-cells : humoral immunity (blood-specificimmunity )
Secrete antibodies into blood stream
Ingest, digest and display parts of antigens
T-cells : cell mediated immunity T cells secretelymphokines - activate / repress immune
response. (e.g. interleukin-2) Direct cell-cell contact Bind to infected cells, deliver toxins, Induce apoptosis
-
8/4/2019 Immune System & Humoral Immunity
11/55
Distinct Cells in Immune System
Lymphocytes ( B cells, T cells ) Determining specificity of immunity
Monocyte/macrophage, dendritic cells, natualkiller cells and other members of myeloid cells
Antigen presentation Mediation of immunologic functions
Specialized epithelial and stromal cells Providing anatomic environment
-
8/4/2019 Immune System & Humoral Immunity
12/55
Acquired immunity.
Characteristics:
Immunological recognition .
Discrimination between self & non-self.Depending on displaying of specific markersCapacity to make Immune response to foreign A g is developed in latefoetal stage or after birth. Immunilogical Silence.
Immunological specificity .Immunological memory .
-
8/4/2019 Immune System & Humoral Immunity
13/55
Acquired immunity.
Immune system mounts immune response .
Immune response must:
R ecognise micro-organism / parasite as foreign.
R espond by production specific antibodies &lymphocytes.
Mediate elimination of organisms.
-
8/4/2019 Immune System & Humoral Immunity
14/55
The discovery of B cell immunity
1954 - Bruce Glick, Ohio S tate University
S tudies on the function of the bursa of Fabricius, a lymphoid organ in thecloacal region of the chicken
Bursectomized chickenswere later used in
experiments to raise
antibodies to Salmonellaantigens
None of thebursectomized
chickens made anti-Salmonellaantibodies
Bursa was later found to be the organ in which antibody producing cells developed antibody producing cells were thereafter called B cells
Mammals do not have a bursa of Fabricius
-
8/4/2019 Immune System & Humoral Immunity
15/55
1 . Cellular immunity - B
lymphocytes.Found in lymph nodes, liver & spleen.
Bone marrow-derived.
Mature in Peyers Patches of Intestine.
During maturation, antigen-specified Abdisplayed on cell surface.
If the cell activated by antigen, B cells secreteantibody.
-
8/4/2019 Immune System & Humoral Immunity
16/55
-
8/4/2019 Immune System & Humoral Immunity
17/55
R
Markers of Self
Muscle cell
Nervecell
Epithelialcell
Leukocyte
Class I MHC self-marker protein
-
8/4/2019 Immune System & Humoral Immunity
18/55
R
Ma r r f - lf
- lf l t
A tib d
itlass I MHC r t i
it
A tib d
A tig
A tig
Bac t ri a
Non -se lf ne r e ce ll
AR ir s
-
8/4/2019 Immune System & Humoral Immunity
19/55
Major Histocompatibility Complex (MHC)
The major histocompatibility complex (MHC) is a largegenomic region or gene family found in the short arm of chromosome 6.HLA antigen system-Group of genes present in MHC mol.The proteins encoded by the MHC are expressed on thesurface of cellsClass MHC I found in every cell , presents Ag to Cytotoxic TcellsClass MHC II on B cells , otherAPC , Presents A g to TH cells
-
8/4/2019 Immune System & Humoral Immunity
20/55
Humoral Immunity
A ntibody ( A b) Proteins made in response to exposureto bacteria and other pathogens,
toxins, plant polen and red blood cellsthat the body recognized as alien, ornonself
A ntigen ( A g) A substances that causes thebody to produce specific
antibodies or sensitized T cells
-
8/4/2019 Immune System & Humoral Immunity
21/55
An antigen (or immunogen) is a chemical substance thatcauses the body to produce specific antibodies(anti body g e n eration)As a rule, antigens are proteins or large
polysaccharides .Antibodies are formed against specific regions onantigens called epitopes , or antigenic determinants.
The Nature of Antigens
-
8/4/2019 Immune System & Humoral Immunity
22/55
Haptens
A hapten is a low-molecular-weight substance that cannot cause theformation of antibodies unless combined with a carrier molecule;
once the antibody against hapten has been formed haptens willreact with their antibodies independent of the carrier molecule.
Figure 17 .4
-
8/4/2019 Immune System & Humoral Immunity
23/55
The Nature of Antibodies
An antibody, or immunoglobulin (Ig), is a protein producedby B cells in response to an antigen and is capable of combining specifically with that antigen .Antibodies recognize and react with antigenic determinantsor epitopes .
Figure 17 .3
-
8/4/2019 Immune System & Humoral Immunity
24/55
Antibody S tructure
Figure 17 .5 a-c
-
8/4/2019 Immune System & Humoral Immunity
25/55
Generation of immune response.
~ 4 -7 days to generate immune response.
> 7 days get primary immune response .1 st IgM produced then IgG.After ~3 weeks primary immune response turnedoff.Ab producing cells & memory B cells formed.
Memory B cells secrete ab when same agentencountered again.This is secondary immune response .Memory lasts weeks / years.
-
8/4/2019 Immune System & Humoral Immunity
26/55
Activation of B cells to produce antibodies
F i u re 17 .4 - O v er vie w
T- de e n de n t an ti e n
-
8/4/2019 Immune System & Humoral Immunity
27/55
Activation of B cells to produce antibodies
T independent antygen -Antigens that stimulate B cells
without help of T cellsRepeating subunits polisaccharides or lipopolisaccharidesCan bind multiple receptors
F ig r e
.6
-
8/4/2019 Immune System & Humoral Immunity
28/55
Helper T Cells
Figure 17 .1 3
-
8/4/2019 Immune System & Humoral Immunity
29/55
S tages of Humoral Immune Response
-
8/4/2019 Immune System & Humoral Immunity
30/55
Two-Signal Model of Humoral Immune R esponse
-
8/4/2019 Immune System & Humoral Immunity
31/55
-
8/4/2019 Immune System & Humoral Immunity
32/55
FUNCTIONING OF THE IMMUNE SYSTEM
-
8/4/2019 Immune System & Humoral Immunity
33/55
Antigen ReceptorsThe humoral andcell-mediated responsesboth rely on antigen
receptorsReceptor versus LigandAn antigen receptor is a receptor whose
ligand is an antigenAntibodies are only one class of antigenreceptors
-
8/4/2019 Immune System & Humoral Immunity
34/55
BINDINGBINDING NO BINDING NO BINDING
BACTE R IABACTE R IA
R ECEPTO R R ECEPTO R
L IGANDL IGAND
LYM PHOC Y TELYM PHOC Y TE LYM PHOC Y TELYM PHOC Y TE
R ECOGNIZES BACTE R IAR ECOGNIZES BACTE R IA DOES NOT R ECOGNIZE BACTE R IADOES NOT R ECOGNIZE BACTE R IA
Receptor-ligand interactions lock and key
-
8/4/2019 Immune System & Humoral Immunity
35/55
Monomer80% of serum antibodiesFix complementIn blood, lymph, intestineCross placentaEnhance phagocytosis;neutralize toxins &viruses; protects fetus &newborn
Half-life = 23 days
IgG antibodies
-
8/4/2019 Immune System & Humoral Immunity
36/55
Pentamer5 -1 0% of serumantibodiesFix complement
In blood, lymph, on BcellsAgglutinates microbes;first Ab produced inresponse to infectionInvolved in response toABO blood group
Half-life = 5 days
IgM antibodies
-
8/4/2019 Immune System & Humoral Immunity
37/55
Dimer1 0-15 % of serumantibodiesIn secretions, mucus,salvia, tears, and brestmilkMucosal protection
Half-life = 6 days
IgA antibodies
-
8/4/2019 Immune System & Humoral Immunity
38/55
Monomer0.2% of serumantibodies
In blood, lymph, on BcellsOn the surface of B
cells, initiate immuneresponseHalf-life = 3 days
IgD antibodies
-
8/4/2019 Immune System & Humoral Immunity
39/55
Monomer0.002% of serumantibodies
On mast cells andbasophils, in bloodAllergic reactions; lysis
of parasitic wormsHalf-life = 2 days
IgE antibodies
-
8/4/2019 Immune System & Humoral Immunity
40/55
Ag-Ab Binding
Antigen-antibody complex A ffinity Specificity
-
8/4/2019 Immune System & Humoral Immunity
41/55
The Results of Ag-Ab Binding
Figure 17 .9
-
8/4/2019 Immune System & Humoral Immunity
42/55
-
8/4/2019 Immune System & Humoral Immunity
43/55
-
8/4/2019 Immune System & Humoral Immunity
44/55
General Categories of ImmunityDisorders
1.Hypersensitivity2.Autoimmunity3.Immunodeficiency
-
8/4/2019 Immune System & Humoral Immunity
45/55
HYPERSENSITIVITY
overactive or hyperactive state of theimmune system.
Four Mechanisms of Hypersensitivity1.Type 1 Hypersensitivity (Anaphylactic)2.Type 2 Hypersensitivity (Cytotoxic)3.Type 3 Hypersensitivity (Immune Complex
Mediated)4.Type 4 Hypersensitivity (Cell Mediated)
-
8/4/2019 Immune System & Humoral Immunity
46/55
Type 1 Hypersensitivity (Anaphylactic)
mediated by IgE, formed in response to aparticular antigen (allergen) bound to mast
cells and basophils (release vasoactive aminesand cytokines)
2 phases:
Initial (rapid) responseSecond (delayed) phase
-
8/4/2019 Immune System & Humoral Immunity
47/55
Type 1 Hypersensitivity (Anaphylactic)
2 Types of AnaphylaxisLocal Anaphylaxis
Asthma, rhinitis, angioedema,urticaria
Systemic AnaphylaxisLife threatening
Laryngeal edema, bronchospasm,pulmonary edema, hypotension
-
8/4/2019 Immune System & Humoral Immunity
48/55
Type 2 Hypersensitivity (Cytotoxic)
mediated by antibodies against intrinsic orextrinsic antigens adsorbed on the cell surface
or on other tissue components.Transfusion reactionsErythroblastosis fetalisCertain drug reactions
Good Pasteure DiseaseMyasthenia GravisGraves Disease
-
8/4/2019 Immune System & Humoral Immunity
49/55
Type 3 Hypersensitivity (Immune-Complex)
Mediated by antigen-antibody complexes-immune complexes forming either in the
circulation or at extravascular sites of antigendeposition
Rheumatic fever
-
8/4/2019 Immune System & Humoral Immunity
50/55
Type 4 Hypersensitivity (Cell mediated)
Initiated by specifically sensitized T-lymphocytes
Delayed type of hypersensitivityTuberculosis
T-cell mediated cytotoxicity
Viral infections, graft rejection
-
8/4/2019 Immune System & Humoral Immunity
51/55
-
8/4/2019 Immune System & Humoral Immunity
52/55
IMMUNODEFICIENCY
Subdivided into:Primary
hereditary loss of immune systemSecondary
acquired
-
8/4/2019 Immune System & Humoral Immunity
53/55
IMMUNODEFICIENCY
Subdivided into:Primary
Brutons disease (deficient B cell)DiGeorge Syndrome (deficient T cell)Isolated IgA DeficiencySevere combined ImmunodeficiencyX-linked agammaglobulinemia (XL A )
patients don t have any mature B cell- can't make antibodies
-
8/4/2019 Immune System & Humoral Immunity
54/55
Autoimmunedisorder Symptoms
Target of Antibodies
Glomerulonephritis L ower back pain Kidney cell antigen that
resembles Streptococcusantigen
Graves disease R estlessness, weight loss, irritability,increased heart rate and blood
pressure
Thyroid gland antigen
M yasthenia gravis M uscle weakness Nerve message receptors onskeletal muscle cells
Pernicious anemia Fatigue and weakness Binding site for vitamin B oncells lining stomach
R heumatoid arthritis Joint pain and deformity Cells lining joints
Systemic lupuserythematosus
R ed rash on face, fever, weaknessand kidney damage
DNA, neurons, blood cells
Type I diabetes Thirst, hunger, weakness, emaciation Pancreatic beta cells
Ulcerative colitis L ower abdominal pain Colon cells
-
8/4/2019 Immune System & Humoral Immunity
55/55