NTA Level 5 • Semester 1 • PST05103

Introduction to Immunology

Pharmaceutical Microbiology • Source Session/Topic 45

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Session 45: Introduction to Immunology

Total Session Time: 60 minutes

Pre-requisites

• Human anatomy and physiology

Students Learning Tasks

By the end of this session students are expected to be able to:

• Explain e terms used in immunology and immunization

• Describe types of immunity

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board and chalk/whiteboard markers

SESSION OVERVIEW

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: Common Terminologies Used in Immunology (10 minutes)

• Immunity

o Immunity is the ability of the body to defend itself against

diseases

• Immunology

o Immunology is the study of immunity

• Immune response

o A response generated against a potential pathogen

• Granulocytes

o Are leukocytes that contain densely staining granules

• Monocytes

o Are small leukocytes that circulate in the blood

• Phagocytosis

o Is a process whereby cells of the immune system known as

phagocytic cell e.g. a neutrophil, recognize, ingests and destroys

a pathogen

• Antigens

o Are substances that are capable of stimulating the immune system

to produce specific immune response against them

• Antibodies

o Are specific substances produced by the immune system in response

to exposure to an antigen

STEP 3: The Immune System (10 minutes)

• The immune system is the system of specialized cells and organs that

protect the body from diseases

• The immune system functions to protect the body against bacterial and

viral infections and destroy cancer cells and foreign substances

• When the immune system is weakened, its ability to defend the body

also weakens. This allows pathogens to grow and flourish in the body,

and cause diseases

• The immune system also performs surveillance of tumour cells, and

immune suppression has been reported to increase the risk of certain

types of cancer

• The immune system protects the body from infection through various

lines of defence.

• The immune system is a complex system of structures and processes that

work together to protect the body

• The immune system is made up of two components derived from the

central (bone marrow and thymus) and peripheral (spleen, lymph nodes

and lymphatic channels, tonsils, adenoids, Peyer's patches, and

appendix) lymphoid organs;

o The molecular component

▪ This component uses specific and nonspecific molecules to

protect the body against foreign substances and pathogens

▪ Molecules of the immune system;

• Immunoglobulins

• Lymphokines

o The cellular components

▪ This component consists of immune cells that protect the

body

▪ Cells of the immune system are white blood cells

• Granulocytes

• Lymphocytes

• Monocytes

• Macrophages

STEP 4: Types of Immunity (25 minutes)

• There are basically two types of immunity, innate immunity and

acquired immunity

• Innate immunity

o It is an immunity that an individual is born with, it is pre-

existing in the body

o It is the first line of defence

o It is non-specific and non-adaptive

▪ It produces the same responses for all potential pathogens

o Innate immunity includes;

▪ Physicochemical barriers (e.g. skin, saliva, lysozymes etc.)

• These physical barrier kills or prevent entry of

pathogens

▪ Cells (e.g. macrophages, neutrophils, basophils, mast cells

etc.)

• These cells attack and kills foreign organisms and toxins

▪ Processes

• Processes such as inflammatory reactions and phagocytosis

limit spread of infection

o These components protect the body for the first few days of an

infection

o Sometimes innate immunity is enough to clear the pathogen

• Acquired immunity

o This is the type of immunity that is not present at birth

o It is the second line of defence which involves building up memory

of encountered infections so can mount an enhanced response

specific to the pathogen or foreign substance

o Acquired immunity is adaptive

o It involves

▪ Antibodies

• which generally target foreign pathogens roaming free in

the bloodstream

▪ T cells

• which are directed especially towards pathogens that have

colonised cells and can directly kill infected cells or

help control the antibody response

o Acquired immunity has two components; humoral immunity and cell-

mediated immunity

o Humoral immunity is mediated by antibodies while cell-mediated

immunity is mediated by immune cells

o Acquired immunity is either active or passive

o Active acquired immunity;

▪ It is induced after contact with a foreign substance or

pathogen (antigen)

▪ After exposure the body actively produces antibodies and

immune cells that will fight against the pathogens

▪ Active acquired immunity is acquired either artificially

e.g. by injection of antigen (e.g. vaccines) or naturally e.g.

after a clinical or subclinical infection

▪ Advantage:

• Produces long term immunity

▪ Disadvantages;

• Slow onset of immunity

• Requires prolonged contact with antigen

o Passive acquired immunity

▪ Passive acquired immunity is naturally acquired from the

mother or artificially produced e.g. by injection of an

antibody containing preparation

▪ Advantage:

• Immediate action

▪ Disadvantages

• Short lived

• Hypersensitivity reaction

STEP 5: Key Points (5 minutes)

• Immunity is the ability of the body to defend itself against invading

pathogens or toxin

• The immune system consists of innate and acquired components of the

immunity

• The innate component is pre-existing, comprised of physical barriers

such as skin and mucous membrane together with chemical substances

produce on these surfaces

• Acquired immunity is not inborn, but acquired after an exposure to

antigens. It is specific. It is comprised of molecules and cells.

• Active acquired immunity involves exposure to an antigen and

production of life long immunity

• Passive acquired immunity involves exposure to antibodies which

produce short term immunity

• Antigens are substances that elicit production of specific immune

response in the body

STEP 6: Evaluation (5 minutes)

• What is an antibody?

• What is active immunity?

• How is passive immunity acquired?

References

Hugo and Russell (2011), Pharmaceutical Microbiology 8th Edition, Willey-

Blackwel publications

Karen C. Carroll et al (2013); Jawetz, Melnick and Adelberg’s Medical

Microbiology 26th Ed. McGraw Hill Co. Inc.

Greenwood et al (2012); Medical Microbiology, 18th edition Churchill

Livingstone

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