Fever B-cells

Inflammation T-cells

Phagocytosis K cells

Physical Barrier NK cells

Complement Antibodies

Humoral Cell-Mediated

B-cells T-cells

Antibodies Cell-cell combat

• Humoral Immunity

B-cells

Antibodies

• Cell-Mediated Immunity

Lymphoid Stem Cells

Lymphoid Stem Cells NK-cells B-cells

T-cells

Cell-mediated Surveillance Ab-mediated

immunity immunity

1. T lymphocytes

• cells produced in marrow, specialized in thymus
• surface studded with T-receptors
• able to recognize antigens
• T-cells attack pathogens themselves
• self-tolerance

1. B lymphocytes

• produce antibodies
• made in marrow, mature in marrow
• surface studded with antibody the B-cell produces
• react to a specific antigen

1. Antibodies

• Y-shaped protein molecules

• 5 classes of Ab

1. Third population cells (null cells)

• cell killing
• K- cells
• NK- cells

D) The Immune Response

1. T-cells & Cell-Mediated Immunity

• stimulate response of both T-cells & B-cells
• activate B-cells to make Ab’s
• AIDS

1. T_s => suppressor T-cells

• inhibit T-cell & B-cell activity
• moderate immune response

1. T_c => cytotoxic T-cells

• responsible for cell-mediated immunity
• direct physical/chemical attack of Ag

1. T-cell Activation

1. Ag presentation

• MHC I or MHC II

1. Ag recognition by T-cells

• CD8 => T_c and T_s
• CD4 => T_H

1. T-cell Activation

T-cell (inactive)

T-cell (active)

T_C T_H T_S

1. B-cells & Ab-mediated immunity

1. B-cell Activation

1. B-cell sensitization
2. B-cell activation

• T_H cells, Memory B-cells & Plasma cells

B-cell (sensitized)

B-cell (activate)

1. Overview

T_C cells Specific Defenses Ab’s

of T-cells of B-cells

T_S cells

2. Therapeutic Applications of Immunity

1. Immunization

• Immunization => preventive techniques of artificially inducing an immune response
• stimulate the immune system without exposing the body to an infection
• killed, attenuated or killed vaccine
• rabies

1. Use of Antisera

• active immunity => immunity induced by vaccination
• passive immunity => protection imparted in the form of ready-made antibodies from outside the body

1. Natural passive
2. Artificial passive

• antiserum
• erythroblastosis fetalis

3. Immune-Mediated Tissue Injury

• hypersensitivity => "too much immunity"

1. Hypersensitivity reactions (four types)

• mast cells => skin, respiratory system, intestines

1. Type I: Immediate Hypersensitivity (Anaphylaxis)

• First exposure causes no noticeable reaction
• Second exposure => mast cells release histamine

• Phases:

1. early

• 5-45 minutes
• skin, eyes, nasal cavity, lungs

1. late

• 2 hours-3 days
• chemotactic factors
• forms:

• epinephrine
• treatment

1. Type II: Ab-Dependent Cytotoxicity

• Ab attach to surface of individual cells (RBC’s, kidney cells)
• Ab attract K-cells
• Myasthenia Gravis, Graves Disease, Erythroblastosis Fetalis

1. Type III: Immune-Complex-Meidated Hypersensitivity

• Immune complex => Aggregation of Ag & Ab’s
• removed from blood by liver and spleen
• Excess Ag or Ab
• Vasodilation, increased permeability, chemotaxis
• Rheumatoid Arthritis, Immune Complex Glomerulonephritis

1. Type IV: Cell-Mediated, Delayed -Type Hypersensitivity

• T_C cells, NK-cells, macrophage
• Tuberculosis, contact dermatitis, acute/chronic transplant rejection

Ag presentation + T_H cells

T_C cells, macrophage, NK cells

Lymphokines, cellular cytotoxicity

1. Tissue Transplantation

• cell surface protein "fingerprint" => chromosome 6 => MHC
• ABO, age, response/tolerance to immunosuppression drugs, further diseases, previous transfusion/transplant
• Tissue vary in immunogenicity

Least Most

Activation & T_H cells move T_H cells interact

Proliferation to graft site with B-cell

of T_C cells

Release lymphokines Ab production

Focused attack Monocyte/macrophage Ab attach to MHC

on tissues to graft site of graft tissue

Graft tissue Graft tissue Graft tissue

attacked attacked attacked

• Acute rejection
• Chronic rejection
• Improving graft survival

4. Immune Deficiency Syndromes

1. Primary Immune Deficiencies

• B-cell, T-cell, combined B & T-cell, defects in phagocytosis/cytotoxicity and complement components
• often determined genetically

1. B-cell deficiencies

• recurrent/overwhelming infections by viruses that are normally neutralized by Ab’s or by bacteria that can resist phagocytosis unless attacked by an Ab.
• Rubella, staphylococcus, influenza
• Isolated IgA defieciency

1. T-cell Deficiencies

• result in chronic or recurrent infections with viruses, yeast & fungi
• DiGeorge Syndrome

1. SCID (Severe Combined Immunodeficiency Disease)

• disorder of both T-cell and Ab production & function
• autosomal recessive or X-linked diseases
• common stem cell disorder
• opportunistic infections
• bone marrow transplant

1. Secondary Immune Deficiencies

1. Thymus

• atrophy after puberty
• decreased capacity to mount a T-cell mediated immune response with increasing age
• increase in self-reactive Ab’s

1. Diet
2. Primary Disorder

• tumor, extensive burns, diabetes mellitus

1. Medical Treatment

• immunosuppressant therapy, anaesthesia, chemotherapy and radiation therapy

1. Stress

• interaction between neuroendocrine and immune
• corticosteroids
• IL-2

1. AIDS (Acquired Immune Deficiency Syndrome)

1. HIV-1 (Human immunodefieciency virus)

Viral DNA merges with host DNA

1. Pathogenesis

• latent period => HIV present but inactive (may not really exist)

1. progression

1. Infection
2. Acute phase (30-50%)
3. Seroconversion
4. Chronic phase
5. Crisis phase

• AZT
• AIDS cocktail
• Vaccine

1. Impact of T_H cells

Decrease in T_H cells

Impaired Impaired Impaired

Ab production inflammatory cellular

response immunity

Increased rate & Tumor Growth

severity of infection

5. Autoimmune Disorders

1. Systemic Lupus Erythematosus
2. Rheumatoid Arthritis
3. Scleroderma

Immunity

Innate Acquired

Specific Immunity