Immunology Lecture 1

The study of the body’s immune system—including its components, functions, and disorders.

What is immunology?

Injecting antigen to produce immunity by eliciting a protective immune response prior to exposure.

What is immunization/vaccination?

A foreign substance capable of eliciting an immune response.

What is an antigen?

A glycoprotein (immunoglobulin) produced in response to an antigen.

What is an antibody?

The ability to resist a particular infection; may increase after recovery.

What is immunity?

Study of non-cellular components in blood (antigen and antibody).

What is serology?

A foreign substance that induces an immune response.

What is an immunogen?

The antibody binding site; a single antigenic site.

What is an epitope?

Self vs non-self; two overlapping systems; specificity; diversity; clonal selection; memory; regulation.

Name the seven main concepts of immunity.

The body’s own cells and proteins recognized as safe.

What is self in immunology?

Foreign cells or molecules recognized as threats.

What is non-self in immunology?

The balance between immune defense and tolerance, preventing underreaction and overreaction.

What is immunological homeostasis?

Absence or reduced immune response leading to infection susceptibility (e.g., SCID).

What is hyporeactivity?

Excessive immune response, including autoimmunity and allergies.

What is hypereactivity?

Immune attack on self; example rheumatoid arthritis.

What is autoimmunity?

Excessive or uncontrolled immune cell growth causing damage (e.g., multiple myeloma).

What is immunopathology/immunoproliferative disease?

Innate/Natural and Adaptive/Acquired.

What are the two overlapping immune systems?

Non-specific recognition; always present; first line of defense; rapid; no immunological memory.

What are innate immunity characteristics?

Found only in vertebrates; induced; specificity for pathogens; longer to activate; induces memory; enhanced response with prior exposure.

What are adaptive immunity characteristics?

Humoral (B-lymphocyte–produced antibodies) and Cell-mediated (T-lymphocyte–mediated responses).

What are the two main types of acquired immunity?

Antibodies that neutralize and eliminate extracellular microbes and toxins.

What do B-lymphocytes produce?

Cytokines and other substances; activate phagocytes to destroy intracellular microbes.

What do T-lymphocytes do?

Administration of a tetanus booster.

In the Adam case, what action was taken because the wound was dirty?

Humoral (antibody-mediated) immunity.

Which branch of adaptive immunity neutralizes toxins?

Active: immune system responds and creates products after exposure or vaccination. Passive: antibodies transferred from another individual or animal.

How is acquired immunity obtained? Active vs Passive.

Immune system responds and creates protective products after exposure.

What is active immunity?

Immunity conferred by transfer of antibodies from another individual or animal.

What is passive immunity?

Activation occurs through interaction of antigen with specific lymphocyte receptors (BCRs and TCRs).

What is specificity in acquired immunity?

DNA rearrangement creates thousands to billions of different variable region sequences in receptors.

What is diversity in the immune system?

About 10 billion.

Approximately how many antibodies can humans produce?

A small number of B and T cell clones bind antigen; activate, proliferate, differentiate into plasma cells and memory cells.

What is clonal selection?

Differentiated B cells that secrete antibodies.

What are plasma cells?

Memory B and T cells that respond rapidly upon re-exposure.

What are memory cells?

Response to first exposure to antigen; mediated by naïve lymphocytes.

What is the primary immune response?

A faster and stronger response upon subsequent encounters with the same antigen; mediated by memory lymphocytes.

What is the secondary (anamnestic) immune response?

Primary is slower and smaller; secondary is faster and larger in magnitude.

What are the primary differences between primary and secondary antibody responses?

Elimination; permanent inactivation; inhibition.

What are the three regulation mechanisms of the adaptive immune system?

Extracellular bacteria/parasites/fungi; intracellular bacteria/parasites; viruses; parasitic worms.

What major pathogen categories does the immune system respond to?

Bacteria causing pneumonia or tetanus; fungi like Candida.

Give examples of extracellular pathogens.

Bacteria and parasites such as those causing leprosy, malaria, Leishmaniasis.

Give examples of intracellular pathogens.

Smallpox, chickenpox, influenza.

Give examples of viruses.

Schistosomiasis and Ascaris.

Give examples of parasitic worms.

Detect host and foreign substances and maintain immune homeostasis.

What is the role of the immune system in health?

B-lymphocytes (humoral) and T-lymphocytes (cell-mediated).

Who are the main cellular players in adaptive immunity?

Exposure to antigen that activates the adaptive immune response.

What triggers the formation of memory lymphocytes?

Activation, proliferation, and differentiation of antigen-bound B/T cell clones into effector and memory cells.

What is clonal expansion?

A secondary immune response with higher magnitude upon re-exposure.

What is an anamnestic response?

It informs testing types, interpretation, and correlation with other disciplines.

Why is immunology important in the clinical laboratory?

To induce a protective immune response against a specific organism or toxin before exposure.

What is the main aim of vaccination?

An epitope is the specific antigenic site that an antibody recognizes and binds.

What is the role of epitopes in antibody binding?

Rheumatoid arthritis.

What is an example of an autoimmune condition?

Multiple myeloma.

What is an example of an immunoproliferative disorder?

Innate is rapid; adaptive is slower but specific and memory-based.

What is the difference between innate and adaptive immunity in time to respond?

They provide a faster and stronger response upon re-exposure to the same antigen.

What is the role of memory cells in vaccination?

Failure to properly distinguish self from non-self can lead to autoimmunity.

What happens when self and non-self cannot be distinguished?

Innate immunity.

Which type of immunity provides immediate, non-specific defense?

Humoral immunity (B cells).

Which branch is responsible for antibody production?

Extracellular bacteria, parasites, and fungi.

What constitutes the extracellular immune response category?

Intracellular bacteria and parasites.

Which pathogens are addressed by intracellular immune responses?

Immune system (overall) with regulatory mechanisms.

Which part of the immune system detects host vs foreign substances to maintain homeostasis?

To provide immediate protection against tetanus via antibody/a toxin-neutralizing response.

What is the role of tetanus boosters in dirty wounds?

Memory is one of the seven main concepts of immunity.

How many main concepts of immunity focus on memory?

Clonal selection expands antigen-specific clones; memory cells ensure rapid secondary responses.

What is the significance of clonal selection and memory in immunity?

Immunology informs testing types, interpretation, and cross-disciplinary correlations.

What clinical laboratory concept ties immunology to testing?

An antigenic determinant recognized by a specific antibody.

What is the meaning of an epitope in immunology?