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1


Adaptive vs Innate


Innate:  Defense against any pathogen

 

Adaptive:  Induced resistance to specific pathogen

2


Louis Pasteur


First to observe immunity in chickens

Injected weakened pathogen which did not cause disease

(weakened by lack of nutrients to multiply)

3


Emil von Behring

Diphtheria & Tetanus bacteria

Small amounts of toxin in rabbits survived and blood created Antitoxin

4


Paul Ehrlich


Special property in blood produced by antibodies

 

Serum factors - factors produced by exposure to bacteria and pathogens

5


Stem cell line


develops in bone marrow or fetal liver

Stem cell

Red bone marrow                                     Thymus

B-cells                                                        T-cells

both migrates to lymphoid tissue

(Spleen, Lymph nodes)

6

Humoral immunity vs Cellular immunity

Humoral

Bone marrow


Blood, phlegm, black bile, yellow bile

B- cells, lymphocyte

works against free circulating antigen except intracellular antigens (viruses and microbes)

 

 

Cellular

Thymus

T-cells, lymphocyte

Needed to combat intracellular pathogens & Cancer

T-Cells responds to antigen via TCR (t cell receptor)

T Cells need APC (Antigen presenting cells) via MCH

 

7

Antigen vs Antibodies

Immune system reponse

 

Antigen

Highly specific immune response

Are proteins or large polysaccharide

(Capsules, cell wall, flagella, toxin, fimbriae, viral coat)

 

Non microbe component

Pollen, egg whiate, blood cell surface, serum proteins, surface molecules of transplanted tissue/organs

8


Epitopes


This is how antibodies recognizes antigens

An antigen can have many epitopes

(Size, shape, chemical structure)

 

 

9


Hapten + carrier moleculs

=Hapten-carrier conjugate

 

Penicillin + host proteins = is an antigen, produces allergic response

10


Antibodies


Globular protein - soluble proteins, spherical to elliptical structure

 

Ig

 

 

11


Antibody monomers


Composed of 4 proteins

2 heavy chain

2 light chain

 

Each Antibody has 2 identical binding site that binds to eptiopes (antigen binding site)

 

Variable vs Constant region

Stem of antibody is Fc region

 

12

Ig

Has different immune reponse roles


IgG - Monomer, 80% of serum, Fixed complement, blood, lymph and intestine, crosses placenta, enhances phaogcytosis, neutralizes toxins/virus, protects fetus, 23 days half life

 

IgM - Pentamer, 5-10% serum, Fixed complement, blood lymph, b cells, Agglutinates microbes, 5 days half life, first antibody produced

 

IgA - Dimer, 10-15% of serum, Mucosal protection, secretion, 6 days half life

 

IgD - monomer, .2% of serum, blood, lymph, b cells, initiate immune response, 3 day half life

 

IgE - Monomer, .002% of serum, mast cell, basophils, blood, allergic reaction, lysis of parasitic worms, 2 day half life

13

Multimers


Aggregates of 2-5 monomers

 

 

14

B-cells

Produces antibodies when activated.

Need assistance from TH (T dependaent antigen)

MHC - Major histocompatibility complex - b cells fragments combine with MHC aka antigen processing & presentation

Clonal expansion - B cells divide & daughter cells are produced which synthesize and secretes antibodies

Carries Ig on cell surface

2 types of daughter cell

Plasma cell - Antibodies

Memory Cell - Long lived and responsible for secondary reponse

15


T-independent antigens


B cells w/o T cell stimulation

Binds to multiple receptors

Repeating subunits

16


Protective mechanism of binding antibodies to antigens


Agglutination

Opsonization (antigen is coated to enhance ingestion by phagocytes)

Activation of complement (causes inflammation & lysis)

Neutralization (Blocks Adhesion & Neutralize toxins)

Cytotoxicity (Antibody attaches to target cell causing macrophage, eosinophil, NK cell destruction)

17

T Cells

glycoproteins


T helper cells (CD4+)

helps humoral immunity

MHC Class II binds to B cells and APC

Effector cells

  • TH1 - produces IFN
  • TH2 - activates eosinophils/B cells to proudce IgE
  • Memory cells

 

T cytotoxic cells (CD8+)

becomes cytotoxic t lymphoctye (CTL)

Binds to MHC class I

Recognizes & destroys infected cells/cancer

Are Endogenous antigens

CTL releases perforin and granzymes (induce apoptosis)

 

T regulatory cell suppress t cells against self

18


Adaptive Immunity


Naturally acquired active immunity - resulting from infection

 

Naturally acquired passive immunity - Transplacental or colostrum

 

Artifically acquired active immunity - Injection of antigen (vaccination)

 

Artifically acquired passive immunity - injection of antibody

19


Vaccine types


Attenuated whole agent vaccines - use of live weakened microbes. Provides live long immunity w/o booster

(MMR, measles, mumps, rubella, polio)

It can revert to pathoglogical form

 

Inactivated whole agent vaccine - uses killed microbes

(cholera, Pneumococcal pneumonia)

 

Toxoids - inactivated toxins

(Tetanus, diptheria)

 

Subunit - fragments of microbe that stimulate an immune response. Has fewer adverse effects cuz they cannot reproduce

 

Conjugated - based on capsular polysaccharides

 

Nucleic Acid - DNA is injected in muscle producing protein encoded antigen. Stimulates humoral and cellular immunity

 

Adjuvants - use chemical additive when vaccines fail to stimulate immune response.