Micro 13 Immunology and Serology

Immunization

The process of inducing immunity to a disease through the administration of vaccines.

Immunotherapies

Methods designed and used to enhance or suppress immune responses as a means to treat certain diseases

Immunization

The process of inducing immunity to a disease through the administration of vaccines.

Immunotherapies

Methods designed and used to enhance or suppress immune responses as a means to treat certain diseases

Variolation

A historical method of immunization against smallpox, where powdered scabs from smallpox lesions were inhaled or placed on the skin to induce a mild form of the disease and provide immunity.

Vaccination

The administration of a vaccine to stimulate the immune system and provide protection against a specific disease.

Naturally acquired immunity

Gained through normal events, such as illness

Artificially acquired immunity

Gained through immunization

Active immunity

Immunity that results from the body's exposure to an antigen, leading to the activation of lymphocytes and the production of memory cells for long-lasting protection.

Passive immunity

Immunity that is acquired through the transfer of antibodies from another individual, providing temporary protection without the activation of the recipient's immune system.

Natural passive immunity

During pregnancy, mother’s IgG antibodies cross the placenta

Breast milk contains secretory IgA

Artificial passive immunity

Injection of antiserum containing antibodies for the prevention of disease before or after likely exposure

Antitoxin

Antiserum that protects against a toxin

Hyperimmune globulin

A specialized blood product containing a high concentration of antibodies against a specific pathogen.

Used to provide immediate immunity to individuals at high risk of infection, such as those with weakened immune systems or exposed to certain diseases.

Immune globulin

A blood product containing antibodies to boost the immune system.

Used to prevent or treat various infections in individuals with weakened immune systems.

Herd immunity

The indirect protection of a population against a contagious disease when a large portion of individuals are immune, reducing the spread of the infectious agent.

Attenuated vaccine

A vaccine that contains a weakened form of the pathogen, which can replicate in the body and induce a strong immune response.

Inactivated vaccine

A vaccine that contains a pathogen that has been killed or inactivated, unable to replicate but still capable of stimulating an immune response.

Advantages of Attenuated Vaccines

Single dose usually induces long-lasting immunity due to microbe multiplying in body

Can inadvertently immunize others by spreading

Disadvantages of Attenuated Vaccines

Can sometimes cause disease in immunosuppressed individuals

Can occasionally revert or mutate, becoming pathogenic

Generally, not recommended for pregnant women

Usually require refrigeration

Examples of Attenuated Vaccines

Measles, mumps, rubella, chickenpox, yellow fever

Advantages of Inactivated Vaccines

Cannot cause infection or revert to pathogenic forms

Disadvantages of Inactivated Vaccines

No replication, so no amplification

Several booster doses usually needed

Inactivated whole agent vaccines

A type of inactivated vaccine that contains killed microorganisms or inactivated viruses

Treated with formalin or other chemical that does not significantly change surface epitopes

Examples of inactivated whole agent vaccines

Influenza, rabies, hep A

Toxoid vaccine

A type of inactivated vaccine that contains toxins treated to destroy their toxic properties while retaining their antigenic epitopes.

Examples of toxoid inactivated vaccines

Diphtheria, tetanus

Subunit vaccine

A type of inactivated vaccine that contains key protein antigens or antigenic fragments from a pathogen, avoiding the inclusion of cell parts that may cause side effects.

Examples of subunit inactivated vaccines

Acellular pertussis (aP) vaccine

Recombinant subunit vaccines

A type of inactivated vaccine that is produced using genetically engineered microorganisms

Examples of recombinant subunit inactivated vaccines

hep B virus

VLP (virus-like particle) vaccines

A type of inactivated vaccine that is produced with empty capsids by genetically engineered organisms

Examples of VLP inactivated vaccines

Human papillomavirus (HPV)

Polysaccharide vaccines

A type of inactivated vaccine that contains polysaccharides from capsules

Examples of polysaccharide inactivated vaccines

Pneumococcal vaccine for adults

Conjugate vaccine

A type of inactivated vaccine that links polysaccharides from the pathogen's capsule to proteins, converting them into T-dependent antigens and enhancing the immune response.

Examples of conjugate inactivated vaccines

Haemophilus influenza type b (Hib)

Nucleic acid-based vaccines

A type of inactivated vaccine that includes segments of naked DNA or RNA from infectious agents and induce an immune response

Adjuvant

A substance added to a vaccine to enhance the immune response to the antigens, often by providing danger signals to dendritic cells or triggering an inflammatory response.

Herd immunity

The indirect protection of a population against a contagious disease when a large portion of individuals are immune, reducing the spread of the infectious agent.

Immunotherapies

Methods designed to enhance or suppress immune responses as a means to treat certain diseases.

How do cancer cells evade detection?

Exploiting peripheral tolerance mechanisms to avoid responses against “self” cells

Down-regulate production of MHC molecules so less antigen is presented

Cytokines

Direct immune cell activities

IL-2 stimulates proliferation of T cells

Interferon-alpha increases tumor cell surveillance by T cells

Immunomodulators

Therapies that either boost or suppress the immune response

Cytokines, adjuvants, checkpoint inhibitors

Hyperimmune globulin

An antiserum that contains antibodies to a specific disease, often used for passive immunization.

Immune globulin

A preparation that contains the IgG fraction from many donors, providing a variety of antibodies for passive immunization.

Dendritic cells

Specialized immune cells that play a key role in initiating and regulating immune responses by presenting antigens to T cells.

Adverse effects

Unintended or harmful effects that may occur as a result of vaccination, although they are generally rare and outweighed by the benefits of vaccination.

Poliovirus

A virus that causes poliomyelitis, an infectious disease that affects the nervous system.

Salk vaccine

A vaccine developed by Jonas Salk in the mid-1950s that contains inactivated poliovirus and is administered through injections.

Sabin vaccine

A vaccine developed by Albert Sabin in 1961 that contains attenuated (weakened) poliovirus and is administered orally.

Inactivated polio vaccine (IPV)

A vaccine that contains inactivated poliovirus and provides protection against polio.

Oral polio vaccine (OPV)

A vaccine that contains attenuated poliovirus and is administered orally.

Herd immunity

The indirect protection from infectious diseases that occurs when a large percentage of the population becomes immune, either through vaccination or previous infection, reducing the spread of the disease.

Wild poliovirus

The naturally occurring, non-attenuated strain of poliovirus.

Immunotherapies

Treatments that modify specific immune responses to treat diseases, primarily used in cancer treatments.

Tumor antigens

Proteins expressed by cancer cells that should be recognized and eliminated by the immune system.

Monoclonal antibodies (mAb)

Antibodies produced by clones of a single B cell that recognize a specific epitope.

Naked antibodies

Monoclonal antibodies without attached components

Rituximab

mAbs used to treat some B-cell cancers

Binds to a B-cell surface protein called CD20, thereby marking B cells for destruction

Trastuzumab

mAbs that treats certain breast cancers which express high amounts of human epidermal growth factor receptor 2 (HER2) and interfering with cancer cells’ growth

Conjugated Antibodies

mAbs that delivers a toxin or other molecule to a cancerous cell

Bi-specific Antibodies

mAbs constructed to have two different antigen-binding sites to bind to a protein on T cells as well as a protein found on some cancerous B cells

Increases the chance that the T cell will destroy the B cell

Antibody-dependent cellular cytotoxicity (ADCC)

The process by which antibodies bind to target cells, marking them for destruction by immune cells.

Checkpoint inhibitors

Immunotherapies that interfere with immune checkpoints, allowing the immune system to attack cancer cells.

Examples of Checkpoint Inhibitors

Inhibitors of the PD-1/PD-L1 Pathway, inhibits the “off switch” pathway

Inhibitors of the CTLA-4 Pathway, makes T-cell activation more likely to occur

Chimeric Antigen Receptor (CAR) T Cells

A patient’s own T cells that are genetically engineered to express a modified T-cell receptor, allowing them to recognize and respond to a specific epitope without antigen presentation or co-stimulation.

Oncolytic viruses

Genetically modified viruses that can directly destroy cancer cells and stimulate an anti-tumor immune response.

Therapeutic vaccines

Vaccines used to treat diseases, such as cancer, by stimulating the immune system to target specific antigens associated with the disease.

Autoimmune disease

A condition in which the immune system mistakenly attacks the body's own cells and tissues.

Immunomodulators

Therapies that either boost or suppress the immune response.

Pro-inflammatory cytokines

Signaling molecules that promote inflammation in the body.

Tumor necrosis factor (TNF)

A pro-inflammatory cytokine involved in the regulation of immune cells and inflammation.

Granulocyte-macrophage colony-stimulating factor (GM-CSF)

A protein that promotes the development of antigen-presenting dendritic cells.

Monoclonal antibodies

Antibodies produced from a single clone of cells and are highly specific to a single epitope on an antigen.

Passive immunotherapy

The use of therapeutic antibodies that do not modify the immune response but provide necessary components to treat infectious diseases.

Inhalational anthrax

A severe infectious disease caused by the bacterium Bacillus anthracis, which can be treated using monoclonal antibodies that neutralize a bacterial protein required for the entry of anthrax toxins into host cells.

HIV infections

Human Immunodeficiency Virus (HIV) infections that resist treatment with other medications can be treated using monoclonal antibodies that bind to CD4 and prevent a conformational change required for the virus to enter cells.

Tuberculin skin test

A test used to detect Mycobacterium tuberculosis infection by injecting a purified protein derivative (PPD) from the organism into the skin and observing the development of a swollen, red area at the injection site.

Serology

The in vitro study of antibody-antigen interactions in the fluid portion of blood (serum) to diagnose diseases and determine antibody levels.

Seroconversion

The process of producing antibodies

Antibody titer

The concentration of antibodies in a sample, determined by serial dilution and the reciprocal of the last dilution that gives a detectable antigen-antibody reaction.

Monoclonal antibodies

Antibodies that recognize one epitope on an antigen, produced from a single clone of cells.

Polyclonal antibodies

Antibodies that bind to multiple epitopes on an antigen, produced from multiple B cells responding to immunization with whole or partial agents.

Immunoassays

In vitro tests that use antibody-antigen interactions to detect or quantify antigens or antibodies in a sample.

Direct immunoassays

Immunoassays that identify unknown antigens by attaching them to a solid surface and adding labeled antibodies of known specificity.

Indirect immunoassays

Immunoassays that detect specific antibodies in a patient's serum by attaching known antigens to a surface, adding the patient's serum, and then adding labeled secondary antibodies.

Fluorescent Antibody (FA) Test

A test that uses fluorescence microscopy to locate labeled antibodies bound to antigens fixed to a microscope slide, allowing the visualization of antigen size and shape.

Enzyme-Linked Immunosorbent Assay (ELISA)

A test that uses antibodies labeled with enzymes to convert a colorless substrate to a colored product, allowing the detection of antigens or antibodies.

Western Blotting

A technique that separates proteins of an antigen by size using SDS-PAGE, transfers them to a nylon membrane, and detects the presence of specific proteins using labeled secondary antibodies.

Fluorescence-activated cell sorter (FACS)

A technique that counts and sorts cells labeled with fluorescent antibodies, allowing the tracking of specific cell populations.

Agglutination reactions

Reactions where antibodies cross-link antigens, creating larger complexes that can be phagocytosed by immune cells.

Precipitation reactions

Reactions where antibodies cross-link soluble antigens, forming insoluble complexes that can be precipitated out of solution.

Direct agglutination test (DAT)

A test where antibodies are mixed with antigens (cells, microorganisms) and binding results in clumping.

Hemagglutination

A technique used for blood typing.

Passive agglutination

A method used when antigens are small, where antibodies or antigens are attached to particles (latex beads) to form larger aggregates.

Precipitation reactions

Reactions where antibodies bound to soluble antigens cross-link and form a precipitate.

Ouchterlony technique

An immunodiffusion test that has largely been replaced, but is used to illustrate the concept of antigen-antibody testing.