immunology introduction

1. IMMUNOLOGY
SAFOORA TARIQ
MICROBIOLOGY AND IMMUNOLOGY THEORY
BAQAI MEDICAL UNIVERSITY
PHARMACY PRACTICES

3. DEFINITIONS
• IMMUNOLOGY
• IMMUNOLOGY IS AN EMERGING BRANCH OF MEDICAL SCIENCE THAT DEALS
WITH STUDIES RELATED TO DIFFERENT ASPECTS OF THE IMMUNE SYSTEM LIKE
THE CELLS, STRUCTURE, FUNCTION, RESPONSE AGAINST ANTIGENS, AND
DISORDERS.
• THE BRANCH OF BIOMEDICAL SCIENCE CONCERNED WITH THE RESPONSE OF THE
ORGANISM TO ANTIGENIC CHALLENGE, THE RECOGNITION OF SELF FROM NON-
SELF, AND ALL OF THE BIOLOGICAL (IN VIVO), SEROLOGICAL (IN VITRO), AND
PHYSICAL CHEMICAL ASPECTS OF IMMUNE PHENOMENA.

4. IMMUNOLOGY ( CONT..)
IMMUNOLOGY IS THE STUDY OF OUR PROTECTION FROM FOREIGN
MACROMOLECULES OR INVADING ORGANISMS AND OUR RESPONSES TO
THEM.
HOST – E.G. ME!!!!
FOREIGN MACROMOLECULE, ANTIGEN – E.G. VIRUS PROTEIN, WORM,
PARASITE (EVERYTHING THAT SHOULD NOT BE IN MY BODY).
PROTECT AGAINST PATHOGENS
ELIMINATE DAMAGED OR MALIGNANT CELLS

5. DEFINITIONS (CONT..)
IMMUNITY
STATE OF PROTECTION FROM INFECTIOUS DISEASES.
IMMUNE SYSTEM
THE IMMUNE SYSTEM CONSISTS OF A COLLECTION OF
CELLS, TISSUES, MOLECULES, CHEMICALS, PROCESSES,
AND MECHANISMS THAT FUNCTION TO PROTECT THE
BODY FROM FOREIGN ANTIGENS, SUCH AS MICROBES
(ORGANISMS SUCH AS BACTERIA, FUNGI, AND PARASITES),
VIRUSES, CANCER CELLS, AND TOXINS.

6. DEFINITIONS (CONT..)
•IMMUNE RESPONSE = COLLECTIVE AND
COORDINATED RESPONSE TO THE
INTRODUCTION OF FOREIGN
SUBSTANCES IN AN INDIVIDUAL
MEDIATED BY THE CELLS AND
MOLECULES OF THE IMMUNE SYSTEM.

7. ORGANS OF IMMUNE
SYSTEM
• PRIMARY LYMPHOID ORGANS
– BONE MARROW AND THYMUS
– MATURATION SITE
• SECONDARY LYMPHOID ORGANS
– SPLEEN, LYMPH NODES,
– MALT (MUCOSAL ASSOCIATED LYMPH TISSUE)
– GALT (GUT ASSOCIATED LYMPH TISSUE)
– TRAP ANTIGEN, APC, LYMPHOCYTE PROLIFERATION

9. MAJOR ORGANS OF IMMUNE
SYSTEM
A. THYMUS: THE THYMUS IS AN ORGAN LOCATED IN THE UPPER CHEST.
IMMATURE LYMPHOCYTES LEAVE THE BONE MARROW AND FIND THEIR WAY TO
THE THYMUS WHERE THEY ARE “EDUCATED” TO BECOME MATURE T-
LYMPHOCYTES.
B. LIVER: THE LIVER IS THE MAJOR ORGAN RESPONSIBLE FOR SYNTHESIZING
PROTEINS OF THE COMPLEMENT SYSTEM. IN ADDITION, IT CONTAINS LARGE
NUMBERS OF PHAGOCYTIC CELLS WHICH INGEST BACTERIA IN THE BLOOD AS IT
PASSES THROUGH THE LIVER.
C. BONE MARROW: THE BONE MARROW IS THE LOCATION WHERE ALL CELLS OF
THE IMMUNE SYSTEM BEGIN THEIR DEVELOPMENT FROM PRIMITIVE STEM CELLS.

10. MAJOR ORGANS OF IMMUNE SYSTEM
D. TONSILS: TONSILS ARE COLLECTIONS OF
LYMPHOCYTES IN THE THROAT.
E. LYMPH NODES: LYMPH NODES ARE COLLECTIONS
OF B-LYMPHOCYTES AND T-LYMPHOCYTES
THROUGHOUT THE BODY. CELLS CONGREGATE IN
LYMPH NODES TO COMMUNICATE WITH EACH
OTHER.

11. MAJOR ORGANS OF IMMUNE SYSTEM
F. SPLEEN: THE SPLEEN IS A COLLECTION OF T-
LYMPHOCYTES, B-LYMPHOCYTES AND MONOCYTES. IT
SERVES TO FILTER THE BLOOD AND PROVIDES A SITE
FOR ORGANISMS AND CELLS OF THE IMMUNE SYSTEM
TO INTERACT.
G. BLOOD: BLOOD IS THE CIRCULATORY SYSTEM THAT
CARRIES CELLS AND PROTEINS OF THE IMMUNE SYSTEM
FROM ONE PART OF THE BODY TO ANOTHER.

12. CELLS OF IMMUNE SYSTEM

14. HISTORY OF IMMUNOLOGY
• IN 1798, JENNER’S WORK ON VACCINATION, DESCRIBING A RELATED, YET SAFE PROCEDURE.
NOTED PEOPLE, WHO HAD COW POX, WERE SPARED IN SMALL POX
EPIDEMICS,
INOCULATED BOY WITH PUS FROM MILK MAID WITH COW POX,
AND
RE-INOCULATED SAME BOY WITH INFECTIOUS PUS FROM A
PATIENT IN THE ACTIVE SMALL POX.
NO DISEASE STATE FOLLOWED THESE INOCULATIONS, AND
EXPERIMENT WAS REPEATED SEVERAL TIMES WITH GREAT SUCCESS!

15. HISTORY OF IMMUNOLOGY (CONT..)
• LOUIS PASTEUR- DEMONSTRATING
• THAT IT WAS POSSIBLE TO
ATTENUATE, OR WEAKEN, A
PATHOGEN AND ADMINISTER THE
ATTENUATED STRAIN AS A VACCINE.
• IN 1885, PASTEUR ADMINISTERED HIS
FIRST VACCINE TO A HUMAN, A
• YOUNG BOY WHO HAD BEEN BITTEN
REPEATEDLY BY A RABID DOG

16. HISTORY OF IMMUNOLOGY (CONT..)
• JENNER`S PROVIDED FIRST CLEAR EVIDENCE THAT ACTIVE IMMUNIZATION
COULD BE USED SAFELY TO PREVENT AN INFECTIOUS DISEASE.
• ALMOST 70 YEARS LATER, PASTEUR - INTRODUCED PASTEURIZATION ALSO
RECOGNIZED AND EXPLOITED THE GENERAL PRINCIPLE UNDERLYING VACCINATION
• AT ABOUT 1900, ROLE OF PHAGOCYTES AND CELLULAR IMMUNITY WERE ELUCIDATED
• KILLED VACCINES WERE INTRODUCED
• COMPLEMENT WAS DESCRIBED

17. HISTORY OF IMMUNOLOGY (CONT..)
• IN 20TH CENTURY,
• ACQUIRED IMMUNITY RESULTED FROM BOTH CELLULAR AND HUMORAL ELEMENTS
WERE DEMONSTRATED.
• OPSONIZATION WAS DESCRIBED
• THE TERM ANTIGEN CAME IN TO REGULAR USE

18. THE IMMUNE SYSTEM
Immune
System
Innate
(Nonspecific)
Cellular
Components
Humoral
Components
Adaptive
(Specific)
Cell-
Mediated
Humoral
(Ab)

19. TYPES OF IMMUNITY
• INBORN OR INNATE IMMUNITY: IT IS PRESENT AT BIRTH; THIS IS OUR FIRST LINE
OF DEFENSE.
• ACQUIRED OR SPECIFIC: IT IS NOT PRESENT AT BIRTH BUT BECOMES PART OF
OUR IMMUNE SYSTEM AS THE LYMPHOID SYSTEM DEVELOPS.
• 1970: WHO DEFINED IMMUNITY AS IMMUNE RESPONSE TO ANTIGEN
( FOREIGN BODY) IN FORM OF
• HUMORAL ( ACTIVATION OF B-LYMPHOCYTES)
• CELLULAR (BY ACTIVATION OF T-LYMPHOCYTES

20. THE IMMUNE SYSTEM

21. DISTINCTION BETWEEN INNATE AND
ADAPTIVE IMMUNE RESPONSES
• INNATE IMMUNITY IS NON-ADAPTIVE AND HELPS TO INITIATE ADAPTIVE IMMUNE
RESPONSES (= FIRST LINE OF DEFENSE – BUT LIMITED)
• ADAPTIVE IMMUNITY PROVIDES A MORE UNIVERSAL LINE OF DEFENSE AND HAS
LONG-LIVED MEMORY TO PROVIDE PROTECTION UPON RE-INFECTION

24. 1. THE INNATE IMMUNITY
NATURAL IMMUNE SYSTEM (INNATE IMMUNITY)
 NON – SPECIFIC
 FIRST LINE OF DEFENSE
 REPEATED EXPOSURE - NO AUGMENTATION
 – IMMEDIATE (0-4 HOURS)
COMPONENTS
 BIOCHEMICAL
 PHYSICAL
 CELLS

25. 1. COMPONENTS
a. BIOCHEMICAL
• ENZYMES, C’, ETC.
• SECRETIONS
• PH
b. PHYSICAL
• SKIN
• CILIA
c. CELLS
• PHAGOCYTES, NK
2. EXAMPLE
a. BURN RESPONSE
Lysozymes
Mucus
Sebaceous glands
Skin
Cilia: trachea
Acid in
stomach
Commensal
organisms in
gut & vagina
Spermine in semen
cont…

26. INNATE IMMUNITY
• NONSPECIFIC HOST DEFENSES THAT EXIST PRIOR TO EXPOSURE TO AN ANTIGEN.
INVOLVES THE FOLLOWING COMPONENTS:
– ANATOMIC – SKIN AND MUCUS MEMBRANE
– BIOCHEMICAL – CHEMICAL SECRETIONS
– PHAGOCYTIC – CERTAIN CELLS WHICH ENGULF THE PATHOGEN
– INFLAMMATORY RESPONSE.

27. CONT…
1. ANATOMIC BARRIER-PREVENT ENTRANCE OF PATHOGEN IN THE BODY.
• STRUCTURAL BARRIERS – EFFECTIVE WITH MOST MICROORGANISMS
• SKIN - EPIDERMIS = LAYERS OF TIGHTLY PACKED EPITHELIAL
CELLS. OUTER LAYER IS DEAD CELLS AND KERATIN,
WATERPROOFING PROTEIN
• INNER LAYER SKIN - DERMIS = BLOOD VESSELS, HAIR FOLLICLES,
SWEAT GLANDS, AND SEBACEOUS GLANDS THAT PRODUCE AN
OILY SECRETION CALLED SEBUM
• CILIA AND COUGH REFLEX – HELPS EXPEL MICROBE CONTAINING
MUCOUS
• SNEEZE

28. CONT…
• MUCUS - CONJUNCTIVAE, ALIMENTARY, RESPIRATORY, AND UROGENITAL
TRACTS
• SALIVA, TEARS, AND MUCOUS SECRETIONS WASH AWAY INVADERS
AND CONTAIN ANTIBACTERIAL OR ANTIVIRAL SUBSTANCES.
• ACIDITY (PH 5.6) OF SWEAT, SEBACEOUS GLANDS, VAGINA (PH 5)
AND STOMACH (PH 1) – UNFRIENDLY TO MANY MICROORGANISMS
• ENZYMES PRESENT IN THE SKIN AND STOMACH, TEARS
• NORMAL FLORA - OUT COMPETE PATHOGENS FOR ATTACHMENT SITES
ON THE EPITHELIAL CELL SURFACE AND FOR NECESSARY NUTRIENTS.

29. CONT…
2. PHYSIOLOGIC BARRIERS
• CHEMICAL SECRETIONS PRODUCED BY THE BODY THAT INHIBIT MICROBIAL
GROWTH.
• FOR EXAMPLE, KERATIN , HYDROCHLORIC ACID AND BILE SALT IN GIT,
LYSOZYME ENZYME IN TEARS, CAN CLEAVE THE PEPTIDOGLYCAN LAYER OF
BACTERIAL CELL WALL..
• COMPLEMENT IS A FAMILY OF MORE THAN TWENTY DIFFERENT PROTEINS IN
SERUM THAT FUNCTION AS A NON-SPECIFIC DEFENSE AGAINST INFECTION.
THEY NORMALLY CIRCULATE IN AN INACTIVE FORM
• MAY BE ACTIVATED BY THE CLASSICAL OR ALTERNATE PATHWAYS
• CAN RESULT IN LYSIS OR ENHANCED PHAGOCYTOSIS OF CELLS

30. CONT…
• ACUTE PHASE REACTANTS -A GROUP OF PLASMA PROTEINS WHICH
INCREASE RAPIDLY FOLLOWING INFECTION EG. CRP, WHICH IS
PROBABLY PRODUCED BY THE LIVER, RECOGNISES AND BINDS TO A
WIDE VARIETY OF BACTERIA & FUNGI, ACTS AS AN OPSONIN,
ENHANCING PHAGOCYTOSIS, AND ACTIVATES COMPLEMENT.
• ACUTE PHASE REACTANTS ARE CHEMICALLY VARIED AND INCLUDE:
• C-REACTIVE PROTEIN, SERUM AMYLOID A, MANNOSE BINDING PROTEIN, ALPHA-1
ANTI-TRYPSIN, HAPTOGLOBULIN, FIBRINOGEN, CERULOPLASMIN, ALPHA-1 ACID
GLYCOPROTEIN, COMPLEMENT

31. CONT…
EARLY ACUTE INFLAMMATION INDICATOR:
• INCREASES WITHIN 4-6 HRS OF INFECTION OR TRAUMA
• 100 TO 1000 FOLD INCREASE SERUM CONCENTRATION
• CONCENTRATION DROPS RAPIDLY IN SERUM WHEN STIMULUS REMOVED
• ENHANCES OPSONIZATION, AGGLUTINATION, PRECIPITATION, AND CLASSICAL
PATHWAY COMPLEMENT ACTIVATION – ENHANCES REMOVAL OF IRRITANT

32. CONT…
2.PHAGOCYTOSIS
• IS A FORM OF ENDOCYTOSIS.
• IMPORTANT BODY DEFENSE MECHANISM AND IS A
PROCESS IN WHICH SPECIALIZED CELLS ENGULF AND
DESTROY FOREIGN PARTICLES SUCH AS
MICROORGANISMS OR DAMAGED CELLS.
• MACROPHAGES AND SEGMENTED NEUTROPHIILS ARE
THE MOST IMPORTANT PHAGOCYTIC CELLS.

33. CONT…
• THERE ARE TWO TYPES OF PHAGOCYTIC CELLS.
A) MACROPHAGES OR MONOCYTES
B) POLYMORHONUCLEAR NEUTROPHILS
THESE TWO TYPES MAKE LAGE POOL OF PHAGOCYTIC CELLS CIRCULATING IN THE
BODY.
CIRCULATING MONOCYTES LEAVE THE BLOOD AND ENTER INTO TISSUES TO
BECOME MACROPHAGES.
NK- NATURAL KILLER CELLS ARE LARGE LYMPHOCYTES WHOSE FUNCTION IS TO
KILL UNDESIRABLE CELLS SUCH AS TUMOR CELLS AND VIRUS INFECTED CELLS

36. CONT…
• PHAGOCYTOSIS ...
• ADHERENCE – BINDING OF ORGANISM TO THE SURFACE OF PHAGOCYTIC CELL.
• ENGULFMENT:- IS THE INJESTION OF MICROORGANISMS AND FORMATION OF
PHAGOSOMES.
• DIGESTION – AFTER THE FOREIGN PARTICLE OR M/OS IS INGESTED, CYTOPLASM
LYSOSOME FUSE WITH PHAGOSOME. THE ENZYMES OF LYSOSOME THEN CONTRIBUTE
TO MICROBIAL KILLING AND LYSIS.

37. CONT…
• 4. INFLAMMATION- DESTROYS AND REMOVES M/O AND REPAIRS TISSUES.
• THE PROCESS OF INFLAMMATION MAY BE DIVIDED IN TO THE FOLLOWING
STAGES:
• INITIATION (DAMAGE TO TISSUE)
• TISSUE RESPONSE
• LEUKOCYTE RESPONSE
• TISSUE REPAIR (RESOLUTION)
• CURE.

38. IMPORTANT COMPONENT OF INNATE
PHARAMCY
Natural killer cells Kill virus infected cells
Neutrophils Ingest and destroy microbes
Macrophages and dendritic Ingest and destroy microbes, and
present cells antigen to helper T-cells
Interferons Inhibit viral replication
Complement C3b is an opsonin, membrane attack
complex creates holes in bacterial
membranes
Transferrin and Lactoferrin growth Sequester iron required for bacterial
Fever Elevated temperature retards bacterial
Inflammatory response Limits spread of microbes
APOBEC3G (apolypoprotein is RNA
editing enzyme)
Causes hyper mutation in retroviral DNA
and mRNA

39. CELLS OF INNATE IMMUNITY
• THE INNATE IMMUNE SYSTEM COMPRISES MOSTLY THE CELLS FROM MYELOID PROGENITOR.
• NEUTROPHILS- NEUTROPHILS ARE THE GRANULOCYTIC LEUKOCYTES, THAT HAVE MULTI-LOBED
NUCLEI. THEY ARE THE FIRST CELLS THAT ACT AT THE SITE OF TISSUE DAMAGE TO ELIMINATE
PATHOGENS ESPECIALLY BACTERIA BY PHAGOCYTOSIS. A TYPE OF CELL LOCATED IN THE
BLOODSTREAM, QUICKLY INGESTING AND DESTROYING MICROORGANISMS. NEUTROPHILS RISE IN
NUMBER IN THE BLOODSTREAM THROUGH ILLNESS AND ARE PRIMARILY RESPONSIBLE FOR THE
ELEVATED AMOUNT OF WHITE BLOOD CELLS ASSOCIATED WITH SOME INFECTIONS.
• EOSINOPHILS- EOSINOPHILS ARE ALSO GRANULOCYTIC LEUKOCYTES WITH A KIDNEY-SHAPED,
LOBED NUCLEUS. THEY RELEASE THE CONTENTS OF THEIR GRANULES TO KILL PATHOGENS. THEY
PRODUCE A VARIETY OF GROWTH FACTORS AND CYTOKINES AND HELPS OTHER IMMUNE CELLS.
• BASOPHILS- BASOPHILS ARE THE LARGEST GRANULOCYTIC LEUKOCYTES WITH A BILOBED NUCLEUS.
THEY HAVE HISTAMINE-RICH GRANULES AND INVOLVE IN INFLAMMATORY RESPONSES. THEY HELP IN
THE SECRETION OF CYTOKINES INVOLVED IN THE MATURATION OF T-HELPER CELLS.

40. CELLS OF INNATE IMMUNITY
• MONOCYTES- A TYPE OF PHAGOCYTIC CELL LOCATED IN THE BLOODSTREAM THAT, WHEN
MOVING TO TISSUES, TRANSFORMS INTO A MACROPHAGE. MONOCYTES ARE THE LARGEST
WHITE BLOOD CELLS THAT PRODUCE MACROPHAGES & DENDRITIC CELLS.
• MACROPHAGES ENGULF AND PROCESS CELL DEBRIS, PATHOGENS, AND CANCER CELLS. THEY
ARE INVOLVED IN WOUND HEALING, TISSUE REGENERATION, AND PRO-INFLAMMATORY
ACTIVITIES.
• DENDRITIC CELLS ARE PRESENT IN TISSUES LIKE SKIN, LUNGS, AND INTESTINES. THEY PRESENT
ANTIGENS TO B AND T CELLS AND ALSO SECRETES CYTOKINES. SENSITIVE CELLS INTRODUCE
ANTIGEN TO CELLS IN THE IMMUNE SYSTEM.
• MAST CELLS- ARE GRANULOCYTES, THAT SECRETE HEPARIN, HISTAMINE, OTHER FACTORS.
THEY HELP IN WOUND HEALING, ANGIOGENESIS, AND ELIMINATION OF PARASITES.
• NATURAL KILLER (NK) CELLS (MAY DEVELOP FROM BOTH MYELOID AND LYMPHOID
PROGENITOR). NK CELLS ARE PRODUCED FROM THE BONE MARROW AND ARE FOUND IN THE
BLOODSTREAM AND TISSUES IN REASONABLY LOW QUANTITIES. THEY ARE CYTOTOXIC CELLS
THAT HAVE SMALL GRANULES WITH PERFORINS AND GRANZYMES AND DESTROYS INFECTED
CELLS AND CANCER CELLS RAPIDLY.

42. 2. THE ADAPTIVE IMMUNITY
ADAPTIVE IMMUNITY
 SPECIFIC
 SECOND LINE OF DEFENSE
 REPEATED EXPOSURE - AUGMENTED – MEMORY
 FASTER RESPONSE
 MORE VIGOROUS RESPONSE
 LONGER LASTING RESPONSE
COMPONENTS
 CLASSIC IMMUNE SYSTEM
 CELLS (CELL MEDIATED) =CMI
 SOLUBLE FACTORS (HUMORAL IMMUNITY) = HI

43. ACUIRED IMMUNITY (CONT..)
ACTIVELY AQUIRED
IMMUNITY
• PRODUCED BY ACTIVE FUNCTIONING OF THE
IMMUNE SYSTEM.
• STIMULATED BY INFECTIONS, ANTIGENS
(VACCINES, ALLEREGNS).
• PROVIDES EFFECTIVE AND LONG-LASTING
IMMUNITY
• THERE IS A LAG PHASE REQUIRED FOR THE
FORMATION OF ANTIBODIES.
PASSIVELY AQUIRED
IMMUNITY
• RECEIVED PASSIVELY, NO INVOLVEMENT
OF IMMUNE SYSTEM.
• ACQUIRED BY ADMINISTRATION OF
ANTIBODIES OR SENSITIZED T-CELLS.
• IMMUNITY IS LESS EFFECTIVE AND
TRANSIENT.
• OFFERS IMMEDIATE PROTECTION.

44. ACUIRED IMMUNITY (CONT..)
ACTIVELY AQUIRED
IMMUNITY
• IMMUNOLOGICAL MEMORY IS
PRESENT.
• NOT APPLICABLE IN
IMMUNODEFICIENT HOSTS.
• ACTIVE IMMUNIZATION IS MAINLY
EMPLOYED FOR PROPHYLAXIS.
PASSIVELY AQUIRED IMMUNITY
• NO MEMORY.
• APPLICABLE IN IMMUNODEFICIENT
HOSTS.
• PASSIVE IMMUNIZATION IS MAINLY
EMPLOYED FOR THERAPEUTIC AND
PROPHYLACTIC USES.

45. (CONT..)
SPECIFIC
IMMUNITY CAN BE
ACTIVE OR
PASSIVE, AND
EACH OF THESE
TYPES CAN IN
TURN BE
NATURALLY OR
ARTIFICIALLY

46. CONT…
• PASSIVE IMMUNITY-- IT IS AN IMMUNITY IN WHICH ANTIBODIES PRODUCED
ELSEWHERE ARE GIVEN TO THE INDIVIDUAL.
• I. NATURALLY ACQUIRED PASSIVE IMMUNITY: REFERS TO ANTIBODIES
TRANSFERRED FROM MOTHER TO FETUS ACROSS THE PLACENTA AND TO THE
NEWBORN IN COLOSTRUMS AND BREAST MILK DURING THE FIRST FEW MONTHS
OF LIFE.
• II. ARTIFICIALLY ACQUIRED PASSIVE IMMUNITY: IS INTRODUCTION OF
ANTIBODIES THAT ARE FORMED BY AN ANIMAL OR A HUMAN TO AN INDIVIDUAL
TO PREVENT OR TREAT INFECTION.

47. CONT…
• ACTIVE IMMUNITY IT IS A PRODUCT OF THE INDIVIDUAL’S OWN IMMUNE SYSTEM IN
RESPONSE TO A FOREIGN ANTIGEN.
• I. NATURALLY ACQUIRED ACTIVE IMMUNITY: IS IMMUNITY THAT COMES FROM
INFECTIONS ENCOUNTERED IN DAILY LIFE.
• II. ARTIFICIALLY ACQUIRED ACTIVE IMMUNITY: IT IS STIMULATED BY INITIAL
EXPOSURE TO SPECIFIC FOREIGN MACROMOLECULES THROUGH THE USE OF
VACCINES TO ARTIFICIALLY ESTABLISH A STATE OF IMMUNITY.

48. CONT…
SECOND LINE OF DEFENSE
– GENERATION OF AG-SPECIFIC EFFECTOR CELLS
– EARLY (4-96 HOURS)
– LATE (>96 HOURS)
• CAPABLE OF RECOGNIZING AND SELECTIVELY ELIMINATING SPECIFIC FOREIGN MICROORGANISMS AND MOLECULES(I.E., FOREIGN ANTIGENS).
• UNLIKE INNATE IMMUNE RESPONSES, ADAPTIVE IMMUNE RESPONSES ARE REACTIONS TO SPECIFIC ANTIGENIC CHALLENGES
• DIFFERENT POPULATIONS OF LYMPHOCYTES AND THEIR PRODUCTS ARE THE MAJOR ACTORS TOGETHER WITH ACCESSORY CELLS – ANTIGEN
PRESENTING CELLS (APCS)
• CARDINAL FEATURES ARE :
• SPECIFICITY
• DIVERSITY , MEMORY,

49. CONT…
CARDINAL FEATURES OF ADAPTIVE IMMUNE RESPONSES
• SPECIFICITY –
• SPECIFIC FOR DISTINCT ANTIGEN, AND
• FOR DIFFERENT STRUCTURAL COMPONENTS OF A SINGLE COMPLEX PROTEIN,
POLYSACCHARIDE, OR OTHER MACROMOLECULES.
• PORTIONS OF SUCH ANTIGENS RECOGNIZED BY INDIVIDUAL LYMPHOCYTES ARE CALLED
DETERMINANTS OR EPITOPES.
• THIS FINE SPECIFICITY EXISTS BECAUSE INDIVIDUAL LYMPHOCYTE EXPRESS MEMBRANE
RECEPTORS ABLE TO DISTINGUISH SUBTLE (SLIGHT) DIFFERENCES IN STRUCTURE BETWEEN
DISTINCT ANTIGENS.

50. CONT…
• DIVERSITY- TOTAL NUMBER OF ANTIGENIC SPECIFICITIES OF THE
LYMPHOCYTES IN AN INDIVIDUAL, CALLED THE LYMPHOCYTE
REPERTOIRE, IS EXTREMELY LARGE.
• ESTIMATED MAMMALIAN IMMUNE SYSTEM CAN DISCRIMINATE 109 TO 1011 DISTINCT
ANTIGENIC DATE RUMINANTS.
• THIS PROPERTY OF THE LYMPHOCYTE REPERTOIRE IS CALLED DIVERSITY. IT IS THE RESULT
OF VARIABILITY IN THE STRUCTURES OF ANTIGEN- BINDING SITES OF LYMPHOCYTE
RECEPTORS FOR ANTIGENS.

51. CONT…
• MEMORY- EXPOSURE OF THE IMMUNE SYSTEM TO FOREIGN
ANTIGEN:
• ENHANCES ITS ABILITY TO RESPOND AGAIN TO THAT ANTIGEN.
• RESPONSES TO SECOND AND SUBSEQUENT EXPOSURE TO THE SAME ANTIGEN,
CALLED SECONDARY IMMUNE RESPONSES, ARE USUALLY MORE RAPID AND LARGER
THAN THE FIRST OR PRIMARY IMMUNE RESPONSE.

52. CONT…
• AN EFFECTIVE IMMUNE RESPONSE INVOLVES THREE MAJOR GROUPS OF CELLS:
CELLULAR IMMUNITY (T LYMPHOCYTES), HUMORAL IMMUNITY (B CELLS), AND
ACCESSORY CELLS (ANTIGEN-PRESENTING CELLS).
• THE TWO MAJOR POPULATIONS OF LYMPHOCYTES—B LYMPHOCYTES (B CELLS)
OF HUMORAL IMMUNITY AND T LYMPHOCYTES (T CELLS) OF CELLULAR
IMMUNITY PROVIDE US WITH OUR SPECIFIC ADAPTIVE IMMUNITY

53. CONT…
• SPECIALIZATION –THE IMMUNE SYSTEM RESPONDS IN DISTINCT AND SPECIAL WAYS
TO DIFFERENT MICROBES, MAXIMIZING THE EFFICIENCY OF ANTIMICROBIAL DEFENSE
MECHANISMS. THUS, HUMORAL IMMUNITY AND CELL MEDIATED IMMUNITY ARE
ELICITED BY DIFFERENT CLASSES OF MICROBES OR BY THE SAME MICROBE AT
DIFFERENT STAGES OF INFECTION (EXTRA CELLULAR & INTRA CELLULAR)
• SELF –LIMITATION- ALL NORMAL IMMUNE RESPONSES RETURNING THE IMMUNE
SYSTEM TO ITS RESTING OR BASAL STATE WITH TIME AFTER ANTIGEN
STIMULATIONS, PROCESS CALLED HOMEOSTASIS.

54. Innate Immunity Adaptive Immunity
COMPARISON OF INNATE AND ADAPTIVE
IMMUNITY
• NO MEMORY
• No time lag
• Not antigen specific
• A lag period
• Antigen specific
• Development
of memory
Summary of innate and adaptive immunity