1. B.Sc BIOTECHNOLOGY – Semester IV
SRI HARSHINI DEGREE & PG COLLEGE.
ONGOLE-523001.
Dr Vemu Anil kumar M.Sc, Ph.D.nanobiotechanil@gmail.com
2. Immune system:
• Organisation of Organs, Tissues, Cells and other
Molecules.
• Work against all Micro organisms, Non self
proteins, Cancer cells.
• Immunity can be Specific and Non specific.
• Antibodies and Antigens.
8. Characters and Functions:
• Blood is supplied by Thyroid arteries.
• Lymphatic vessel along with Ateries and veins ends inLymphnodes.
• Nerve supplying thymus arise from Vagus nerve.
• Production of T – Lymphocytes or Thymic lymphocytes.
• T- Helper cells and T-Cytotoxic cells.
• Cell mediated Immunity and Humoral Immunity.
• Most important part – Lymphocyte proliferation.
• Immuno competant.
• Hormones – Thymosin, Thymopoietin, Thymulin.
• T-cells are circulated in to Lymph nodes, Spleen.
• Thymus is active at Neonatal age and becomes dull at Older age (Atropy -
Apoptosis)- replaced by Adipose.
9. 2. Bone marrow
• B – Cell maturation site.
• Bursa fabricius in Birds.
• Semi-solid tissue - spongy or cancellous portions of bones.
• Highly vascular region & Non vascular region.
• Site of hematopoiesis (new blood cell production).
• Red marrow & Yellow marrow – Birth to early adolescence.
• It is composed of hematopoietic stem cells, mesenchymal stem
cells.
• Hematopoietic cells – progenitor cells - Lymphoid stem cells &
Myeloid stem cells – B Lymphocytes and other blood cells.
• B cells with Self reactive antibody receptors were eliminated.
.
10.
11.
12. 3. Bursa of Fabricius
• B – Cell proliferation and differentiation site in Birds.
• The bursa develops as a Dorsal diverticulum of the cloaca.
• Lymphoid follicles.
• Stem cells from yolk sac, foetal liver and bone marrow – Immuno
competent B lymphocytes.
• B cells – Spleen and Lymph nodes (Peripheral lymphoid organs).
• Atrophy – 6 months.
13.
14. 1. Spleen
• Situated on Left abdominal cavity below the Dipahragm.
• Large ovoid organ.
• Surrounded by Tough connective tissue – Capsule.
• Smooth and convex towards the Diaphragm, Concave towards stomach.
• Projections – Trabeculae – Compartments.
• Hilum – Splenic Artery and Vein.
• Two zones: 1. Red pulp 2. White pulp.
• 1. Red pulp –
• Hematopoiesis – till 5th month of gestation.
• Contains Venous sinuses (cavities filled with blood - The spleen also stores blood)
• Splenic cords (connective tissues containing red blood cells and white blood cells).
• Old and defective RBC are destroyed – Iron - returns to the bone marrow.
15. 2. White pulp.
• Contains branches of Splenic artery – PALS – Peri Arteiolar Lymphoid
Sheath - T lymphocyte are present.
• Periphery – B cells.
• Antigens are presented to Spleen – Primary follicles – Secondary
follicles.
• The spleen also produces compounds called opsonins, such as
properdin and tuftsin, that help the immune system.
16.
17. 2. Lymph nodes or Gland
• Present through out the Body linked by Lymphatic vessels.
• Ovoid or Kidney shaped organ.
• Surrounded by Tough connective tissue – Capsule.
• Projections – Trabeculae – Compartments.
• Afferent Lymphatic vessel – Enters - Convex end.
• Efferent Lymphatic vessel - Exit- Concave end.
• Outer – Cortex , Inner – Medulla.
• Cortex :
• Inactivated B cells (Lymphoid follicles) – Proliferating Lymphocytes – Dendritic
macrophages – Antigen presentation – Bursa dependent areas.
• Deeper – Para cortex – T cells – Bursa independent areas.
18. Inner - Medulla
• Large blood vessels, Sinuses and Medullary cords (Bursa dependent areas) –
antibody secreting plasma cells.
• Include plasma cells, macrophages, and B cells.
19.
20. • The mucosa-associated lymphoid tissue (MALT), also called mucosa-associated
lymphatic tissue, is a diffuse system of small concentrations of lymphoid tissue
found in various submucosal membrane sites of the body, such as the
gastrointestinal tract, oral passage, nasopharyngeal tract, thyroid, breast, lung,
salivary glands, eye, and skin.
• MALT constitute about 50% of the lymphoid tissue in human body.
• Contains Phagocytic cells and B&T Lymphoid cells.
• Immunoglobulins are produced – IgA, IgG, IgM, IgE.
3. MALT
21. The components of MALT subdivided into the following:
• GALT (gut-associated lymphoid tissue. Peyer's patches are a component of
GALT found in the lining of the small intestines.)
• BALT (bronchus-associated lymphoid tissue)
• NALT (nasal-associated lymphoid tissue)
• CALT (conjunctival-associated lymphoid tissue)[1]
• LALT (larynx-associated lymphoid tissue)
• SALT (skin-associated lymphoid tissue)
• VALT (vulvo-vaginal-associated lymphoid tissue)
22. Cells of Immune system
Lymphocytes
B - Lymphocytes
T - Lymphocytes
T –Regulator
cells – TH/TS
T –Cytotixic
cells
Null cells
Natural Killer cells
(NK)
Killer cells
(K)
Lymphokine
activated killer cells
(LAK)
23. Lymphocytes
• Recognise the Antigen
• Humoral Immunity
• Cell mediated Immunity
• Hypersensitive reactions
• Found Peripheral blood, lymph, lymph nodes and lymphoid
organs.
• Develop immunocompetence.
24. Functions of Lymohocytes
1. Recognition of antigen – Specific.
2. Induction of Immune response –
Tolerance to specific organs.
3. Immunological memory.
25. T - Lymphocyte
• Pro T cells – Haematopoietic stem cells.
• Development/ Maturation at Thymus.
• Blood stream - 70 to 80%.
• Lymphnodes and Spleen.
• Childhood stage – Thymus dependent differentiation.
• Adults – Secondary lymphoid organs.
• Cell Mediated Immunity.
• Surface antigens - specific – Immunocompetence.
• Presence of glycoproteins – CD – Cluster of differentiation – CD3,
CD4, CD8
26. Two groups:
1. T – Regulator cells (TR) : TH or TS
• Enhancement and Suppression of Antibody formation.
• T Helper cells – B cell activation and T effector cells activation.
• T suppressor cells – Suppress the activation of TH and B cells.
2. Effector T- Cell :
• T – Cytotoxic cells (TC) – Cytolysis - Non self and parasite infected
cells.
• T – Delayed type hypersensitivity (TDTH) – Infectious antigens,
Inflammation, activate macrophages in Delayed type IV
hypersensitivity.
27.
28. B - Lymphocyte
• Derived from Bone marrow.
• Birds – Bursa of Fabricius.
• Low concentration in Blood 20-30%.
• High in Secondary lymphoid organs.
• Primary development in Bone marrow. Secondary development – TH cells –
germinal centre of secondary lymphoid organs – Plasma cells and Memory
cells.
• Humoral immunity or antibody mediated immunity.
• Contains surface glycoprotein – Immunoglobulin – IgM and IgD – Receptor
for FC piece of antibody.
• APC – Antigen presenting cells.
• More than 10,000 antigen receptor site – Later- Specific.
29. • B cells are activated – Plasma cells & Memory cells.
• Plasma cells – 5 to 7 days.
30. Null cells
• Neither T nor B cell.
• Develops inside the bone marrow.
• No surface markers.
• No MHC.
• Non phagocytic.
• Kill the malignant tumor cells, transplanted cells, any abnormal cells
and Virus infected cells.
• Contains Azurophilic granules Large Granular Lymphocytes (LGL).
1. Natural killer cells.
2. Killer cells.
3. Lymphokine activated killer cells.
31. 1. Natural killer cells :
• Severe combined immunodeficiency disease – B&T cells are
absent.
• Kill Tumor cells, abnormal cells, virus infected cells.
• Activated in response to interferons or macrophage-derived
Cytokines.
• Small granules - special proteins - Perforin and Proteases known as
granzymes.
• Perforin forms pores in the cell membrane of the target cell -
granzymes - Apoptosis.
32. 2. Killer cells :
• Surface receptor for FC of IgG.
• Kill cells sesitised with IgG.
• ADCC – Antibody Dependent Cell Cytotoxicity.
3. Lymphokine activated killer cells :
• Activated with Interleukin-2.
• Capable of acting against cells - major histocompatibility complex.
• Cancer treatment.
33. Monocytes Macrophages
1. Macrophages or Phagocytes :
• Lymphnodes – Dendritic
• Lung – Alveolar macrophages
• Liver – Kupffer cells
• Bone marrow – Osteoclasts
• Nervous system – Microglial cells
• Sinovium – Type A lining cells
Blood
34. Important Functions:
1. Phagocytosis.
2. Scavengers.
3. Non – specific immunity.
4. APC.
5. Removes Immune complexes or debris.
6. Become giant cells – epithelioid cells – Pathogens.
7. Produce – IL1, IL6 and TNFα/β –antigen specific activation of CD4 – TH
cells.
8. Produce – hydrolytic enzymes, binding proteins, complement proteins.
35. 2. Neutrophils:
• 60% of leucocytes.
• Phagocytosis – Pinocytosis.
• Granules contain antimicrobial effectors - Body's natural antibiotics.
• ADCC.
• Non specific – Except for Opsonins.
• Acute inflammation – first cells to reach the site of infection.
• Rapid activation towards – Bacterial products or C5a,activated
compound.
36. 3. Eosinophils:
• 3 to 5% of leucocytes.
• Allergic, inflammation, parasitic infections, Ag-Ab complex – Tissues.
• Granules – Hydrolytic enzymes – Extra cellular killing of parasite.
• Phagocytosis – Pinocytosis.
• ADCC – receptor for Fc.
4. Basophils and Mast cells :
• 1% of leucocytes, In tissues – Mast cells. Activated – Allergy.
• Pharmacological mediaters – Histamine, heparin, seratonin, hydrolytic enzymes
mediate Type I hypersensitivity.
• Fc – IgE.
38. Humoral Immunity
Activation phase:
• Invading Bacteria is phagocitized by APC like Dendritic cells, Macrophages, B
cells.
• Lysosome – Phagosome, contains Digestive enzymes to process the Antigen
(Ag).
• Processed Ag are combined with MHC-Class II proteins, and presented on the
surface of APC.
• CD4+ / T helper cells recognize and bind to the Ag –MHC class II protein
complex.
• Now APC release IL1 to activate the T helper cell, Now T cell release IL2 to
proliferate the T cell to produce many T cells with same receptors.
39. Effector phase:
• B cell with IgM that can bind to the same Ag are in activation.
• B cell engulfs the Complex (IgM – Ag) by receptor mediated endocytosis.
• Lysosome – Phagosome, contains Digestive enzymes to process the Antigen.
• Processed Ag are combined with MHC-Class II proteins, and presented on the
surface of B cell.
• Activated CD4+ / T helper cells binds the Ag – MHC class II protein complex.
• T cell releases Cytokines to activate B cell to proliferate.
• B cell – Plasma cell (Ab), with same receptors for Ag and Memory cells.
• Ag-Ab complex – makes easier for Killer cell to destroy the bacteria by
phagocytosis – Killer cell releases proteins to kill the bacteria.
• Complement – Kills the bacteria.
42. Cell mediated Immunity
Activation phase:
• Invading Virus is phagocitized by APC like Dendritic cells, Macrophages, B
cells. Virus also attacks the other epithelial cells.
• Lysosome – Phagosome, contains Digestive enzymes to process the Antigen
(Ag).
• Processed Ag are combined with MHC-Class II proteins, and presented on the
surface of APC.
• Processed Ag in the epithelial cells are combined with the MHC Class I and
presented on to the surface.
• CD4+ / T helper cells recognize and bind to the Ag –MHC class II protein
complex. Activated T cell produces IL2 and IFN-γ.
43. Effector phase:
• CD8+ / Tc cells are activated by IL2, recognise and bind to the MHC I- Ag
complex on epithelial cells.
• Killer T cells are attracted to the site.
• Tc cell releases Perforin to lyse the infected cell.
• Viral infection is controlled.
• T Cell is deactivated by T – Regulatory cells.
• Memory T cell remains .
44.
45. Innate Immunity Mechanism
1. Epithelial surfaces.
2. Anti bacterial substances in blood and tissues.
3. Microbial antagonism.
4. Cellular factors.
5. Inflammation.
6. Fever.
7. Acute phase proteins.
46. 1. Epithelial surfaces.
• Acts as Mechanical barrier.
• Skin and mucous membrane covering the body protect from invasion of
microorganisms.
• High salt concentration, sebaceous secretions and long chain fatty acids posses
Bactericidal activity.
• Mucosa and cilia of the respiratory tract prevent entry of microorganisms at
nasal orifices, those passed behind swept back to the pharynx.
• Cough reflex protects the respiratory tract.
• Nasal and respiratory secretions contains Mucoplysaccharides capable of
combining with Influenza and other viruses.
47. • Mouth is constantly bathed in Saliva and inhibits many micro organisms, and
which are swallowed are killed by gastric juices.
• Conjuctiva of eye is freed from foreign particles by the flushing action of
lachrymal secretions (lysozyme).
• Flushing action of urine eliminates bacteria from the urethra.
2. Anti microbial substances in blood and tissues.
• Complement system posses bactericidal activity Eg : Beta lysin, leukins etc…
• Defense against viral infections is by Interferon.
• Microbial antagonism.
3. Microbial antagonisms:
• Resident bacterial flora prevents colonization by Pathogens.
48. 4. Cellular factors:
• Phagocytic cells ingest and digest the pathogens - Phagolysosome have lytic
enzymes to kill the micro organisms.
• Reticuloendothelial system removes the foreign particles.
• Natural killer cells are defense against viral infections and tumors.
5. Inflammation:
• Non specific defense mechanism activated during tissue injury or irritation.
• Leads to Diapedesis – Increased blood flow through the capillaries.
• Outpouring of plasma helps to dilute the toxins.
49. 6. Fever :
• Rise in temperature – Natural defense mechanism.
• Accelerates the physiological processes.
• Fever stimulates the production of interferons and helps in recovery from
viral infections.
7. Acute phase proteins :
• Sudden increase in plasma proteins during infection or injury. – C Reactive
proteins (CRP), mannose binding proteins, alpha-1-acid glycoprotein, serum
amyloid P etc…
• They activate the Alternate pathway of complements.
• APP Enhance resistance, prevent tissue injury and promote repair of
inflammatory lesions.
50. The Complement system
• Bordet and Gengou (1901) described the Complement fixation test.
• Wasserman complement fixation test for syphilis is the most popular serological
test.
• Complement is present in the sera of all mammals.
• Complement are Heat liable.
• Cytolytic activity undergoes denaturation slowly at room temperature and being
destroyed (inactivated) in 30 minutes at 56°C.
• Complement (C) does bind to Ag – Ab complex only.
• Combination of C with Immunoglobulins (Ig) – Fixation, binding, consumption.
• Only IgM, IgG3, 1 and 2 fix to C but not IgG4, IgA, IgD, IgE.
• C bind to Fc. C not influenced by antigen but only Immunoglobulin class.
51. Components of complement system :
• Complement is a complex of nine different fractions C1 to C9.
• Fraction C1 yields 3 protein subunits – C1q, C1r, C1s.
• Thus C is made up of 11 different proteins.
• C fractions are named C1 to C9 in the sequence of Cascading reaction, Except
C4 comes after C1 before C2 i.e., C1 – C4 – C2…..- C9.
• Factors B, D, P, H, I are involved in Alternative pathway.
• Enzymatically activated C1 is shown as Cī.
• Fragments cleaved from C components during cascade are indicated by small
letters C3a, C3b.
• Inactivated forms are indicated by prefix ‘i’ (iC3b).
52. Complement system activation:
• Complement is activated by Ag-Ab complex and react in a specific sequence as
a Cascade.
• In C cascade Preceding component act as Enzyme on Succeeding component
and cleave them in to Larger fragment and Smaller fragment.
• Lager one usually joins in cascade, smaller one contribute to defense
mechanism by amplifying the inflammatory process, increasing vascular
permeability, inducing smooth muscle contraction, chemo-taxis of leucocytes,
promoting virus neutralization, detoxifying endotoxins and effecting the release
of histamine from mast cells.
• C cascade triggered by two parallel independent mechanisms which differs in
initial steps, once C3 is activated the subsequent steps are same.
53. I. Classical pathway :
• The chain of events in which C components react to activate C1 and lead to
cytolysis is known as the classical pathway.
• It consists of the following steps:
1. The first step is the binding of C1 to the antigen- antibody complex. The
recognition unit of C1 is C1q, which reacts with the Fc piece of bound IgM or
IgG. C1q has six combining sites. Effective activation occurs only when C1q is
attached to immunoglobulins by at least two of its binding sites. One molecule of
IgM or two molecules of IgG can therefore initiate the process. C1q binding in
the presence of calcium ions leads to sequential activation of C1r and s.
54. 2. Activated C1s is an Esterase (C1s esterase), one molecule of C1s can cleave
several molecules of C4. C4 is split into C4a, which is an Anaphylatoxin, and C4b,
which binds to cell membranes along with C1.
3. C14b in the presence of magnesium ions cleaves C2 into C2a, which remains
linked to cell-bound C4b, and C2b which is released into the fluid phase. C4b2a
has enzymatic activity and is referred to as the Classical pathway C3 convertase.
4. C3 convertase splits C3 into two fragments, C3a which is an Anaphylatoxin and
C3b which remains cell-bound along with C4b2a to form a trimolecular complex
C4b2a3b which has enzymatic activity called as C5 convertase.
55. 5. The membrane attack phase of complement activity begins at this stage, with C5
convertase cleaving C5 into C5a, an Anaphylatoxin which is released into the
medium, and C5b which continues with the cascade. C6 and C7 then join together.
• A heat stable trimolecular complex C567 is formed, part of which binds to the
cell membrane and prepares it for lysis by C8 and C9 which join the reaction
subsequently. Most of C567 escape and serve to amplify the reaction by
adsorbing onto unsensitised 'bystander cells' and rendering them susceptible to
lysis by C8 and C9.
• The unbound C567 has chemotactic activity. The mechanism of complement
mediated cytolysis is the production of 'holes', approximately 100 Å in diameter
on the cell membrane.
56. • This disrupts the osmotic integrity of the membrane, leading to the release of
the cell contents.
• Although the classical pathway is generally activated by the antigen-antibody
complex or aggregated immunoglobulin, activation may also be due to other
stimuli, such as DNA, C reactive protein, trypsin-like enzymes or some
retroviruses.
58. II. Alternate pathway or Properdin pathway :
• The central process in the complement cascade is the activation of C3.
• The activation of C3 without participation of C142 is known as the ‘Alternative
pathway'.
• The first step in the alternative pathway is the binding of C3b to an activator.
• C3b is continuously generated in small quantities in the circulation but in the free
state it is rapidly inactivated by the serum protein factors H and I.
• Bound C3b interacts with a serum protein called Factor B (also known as 'C3
proactivator') to form a magnesium-dependent complex 'C3b,B'. This complex is
cleaved by another serum protein Factor D (also called 'C3 proactivator
convertase') into two fragments, Ba and Bb.
59. • Fragment Ba is released into the medium. Fragment Bb remains bound to
C3b. forming the Esterase C3bBb complex, which is the alternative pathway
C3 convertase.
• This enzyme C3bBb is extremely labile. The function of Properdin (also called
Factor P) is to stabilise the C3 convertase. which hydrolyses C3, leading to
further steps in the cascade, as in the classical pathway.
