Immunity

IMMUNITY BY DR.MOHAMMAD KHALID FCPS (Medicine) 4th MPH PHSA PESHAWAR

OBJECTIVES: To make the participants understand 1: the basics of immunity ? 2: innate vs. acquired immunity ? 3: active vs. passive immunity ? 4: immunity and immunization ? 5: disordered immunity ?

WHY TO KNOW IMMUNITY •CDC •C=CONTROL •HOW TO CONTROL AN ATTACK?

DEFENCE • COUNTRY • ATTACKED • TWO WAYS TO FIGHT • HIRE A TRAINED FORCE - QUICK • PREPARE OWN FORCE – TAKES TIME • WHICH IS BEST?

ATTACK

INFECTION

INFECTION

INFECTION

INFECTION

• DEFENCE

MAKE OWN (ACTIVE)

HIRE (PASSIVE)

PHYSICAL (SKIN)

What Is Immunity Immunity is the ability of the body to specifically counteract foreign organisms or substances, called antigens. Antigen? - foreign compounds which initiate an immune response Antibody? - proteins produced by B lymphocytes which attack antigens

What Is Immune System (DEFENCE)?

The immune system is the system of specialized cells and organs that protect an organism from outside biological and chemical influences.

Organs of the Immune System: 1:Primary organs:

Thymus: Responsible for maturation of the T cells. Bone Marrow: Responsible for maturation of B cells.

2: Secondary organs:

- Spleen -Lymphatic system -Highly organized follicles are present in small intestine (Peyerís patches) and tonsils -Mucosa-Associated Lymphoid Tissue

THE IMMUNE SYSTEM HAS A SERIES OF DUAL NATURES, -

self / non-self recognition, general / specific, natural/adaptive=innate/acquired, cell-mediated / humoral, active / passive, primary / secondary.

 INNATE IMMUNITY: - faster-acting - non-specific - no stimulation needed for activation - It is genetically based and we pass it on to our offspring. - present from birth - active round the clock

-

INNATE IMMUNITY:

First-line defenses:

1: physical and chemical barrier – skin and mucus coating of the gut and airways 2: the stomach secretes

gastric acid

-Second-line defense:

Phagocytic cells: 1: Phagocytic cells ( macrophages and neutrophil granulocytes) that can engulf (phagocytose) 2: Phagocytosis involves chemotaxis – chemotactic chemicals – adhesion -by opsonization, opsonins-ingestion-reactive oxygen species and proteases

- Anti-microbial proteins: -several classes of antimicrobial proteins a: acute phase proteins (C-reactive protein) b: lysozyme, and the complement system c: The complement system is a very complex group of serum proteins - interferons - secreted by virus-infected cells

RBCs

macrophage

 ACQUIRED IMMUNITY -adaptive immune system -ensure full/partial immunity against reinfection by the same organism -based on specialized cells called lymphocytes ,produced by stem cells in the bone marrow -Lymphocytes - two major types: B cells and T cells.

- Roughly 80% of them are T cells, - 15% B cells and - 5 % are null Lymphocytes. - B cells produce plasma cells which then produce antibodies - T cells become T helper (CD4) or cytotoxic (CD8) lymphocytes

- If acquired immunity is due to B cells or antibodies (IgA,IgG,IgM,IgD and IgE) it is also called Humoral immunity. - If acquired immunity is due to T cells it is also called Cellular immunity

Acquired Immunity A. Is either active or passive B. Either , naturally acquired or artificially acquired

Active acquired immunity - Long-lasting (usually life-long) - Develops after exposure to antigen - The body manufactures antibodies or sensitized lymphocytes itself – actively

1.This exposure may occur "naturally" (NATURALLY ACQUIRED ACTIVE IMMUNITY) a) It is accidental b) That is, the host unintentionally comes in contact with the antigen c)  Examples are naturally acquired diseases and infections (1)    primary antibody response   IgM appear first followed much later by IgG (2)    secondary antibody response IgG is produced in high concentrations as a result of memory cell formation

2.This exposure may occur artificially (ARTIFICIALLY ACQUIRED ACTIVE IMMUNITY) a)    It is deliberate and planned b)    That is, the host is intentionally exposed to the antigen c)    For example, the infant (or adult) receives          immunizations at  the doctor's office          The individual undergoes a primary and secondary          antibody response

Passive acquired immunity 1. 2. 3. 4. 5.

Is short-lasting Is a "gift" of antibodies produced outside the host's body Mother to newborn Emergency – ATS , ARG Protection for sometime until active immunity develops

1. This acquisition of antibodies may occur "naturally" (NATURALLY ACQUIRED PASSIVE IMMUNITY) a)

also known as congenital immunity

b) 

maternal antibodies transferring to the fetus through the placenta - IgG

c)    maternal antibodies transferring to baby through mother's milk -IgA, with trace amounts of IgG and IgM

2.This acquisition of antibodies may occur "artificially" (ARTIFICIALLY ACQUIRED PASSIVE IMMUNITY) a)

This occurs as a result of antibodies to a particular antigen being deliberately injected into the host

b)

Antiserum – ATS, ARabiesS , Antidiptheria serum

c)

Gamma globulins – ATG, Gamma immune, ARG

APPLICATIONS OF IMMUNITY: -

Vaccination -active artificial immunity

- Serology is the use of laboratory tests to detect antigen and antibody reactions to diagnose infections or do many other tests - Herd immunity - ?

CONTROL OF INFECTION • Vaccine Vs Anti-serum Or Ig • TT Vs ATS or ATG • TOXIN – TOXOID • LIVE ATTENUATED VIRAL / BACTERIAL VACCINES • DEAD BACTERIAL VACCINES • SUB-UNIT VACCINES

Live vaccines:  viral infections. measles, mumps, rubella and chicken pox (varicella)  bacterial vaccine consisting of a strain of Mycobacterium bovis, Bacillus Calmet Geurin (BCG)  carry a serious risk of causing overt disease in some  Can revert to their pathogenic form and cause serious illness.

DEAD / Killed vaccines: • whole organisms inactivated by heat, chemicals or UV irradiation • influenza, hepatitis A, yellow fever, cholera, typhoid, Pertussis • Serious reaction as with Pertussis

Sub-unit vaccines:  subcomponents of the pathogenic organisms , usually proteins or polysaccharides.  Hepatitis-B, rabies vaccines consist of antigenic proteins Toxoid:  diphtheria, tetanus, cholera SYNTHETIC / RECOMBINANT MOLECULAR / DNA VACCINE ADJUVENTS

ROUTES OF ADMINISREATION OF VACCINES • I/D – BCG • I/M – HB VACCINE , DPT • S/C – MEASLES BCG MEASLES ________________________

SKIN

DPT

IM

BACTERIAL

HEP B VIRAL

IMMUNE DISORDERS: Attenuated Or Low Response: HIV,Steroids,Malnutrition,pregnancy Exaggerated Response : Autoimmune disorders, IDDM,RA,SLE,drug reactions,

THANKS