Antibodies and Immunoglobulins Structure Quiz

Types of Immunity

• Passive immunity: preformed antibodies are donated to an individual; does not create memory, acts immediately, and is short term.
• Natural immunity: acquired as part of normal life experiences.
• Artificial immunity: acquired through a medical procedure such as a vaccine.

Categories Of Acquired Immunities

• Natural Immunity: acquired through normal life experiences not induced through medical means.
• Artificial immunity: produced purposefully through medical procedures (also called immunization).

Passive Immunity

• Consequence of one person receiving preformed immunity made by another person.
• Includes immune serum globulin (ISG), gamma globulin, which contains immunoglobulin extracted from pooled blood.
• Used in preventing measles and hepatitis A and in replacing antibodies in immunodeficient patients.
• Acts immediately; protection lasts 2-3 months.

Vaccination

• Artificial active immunity: deliberately exposing a person to material that is antigenic but not pathogenic.
• Involved in presenting antigen to T-cells.

Cellular Immunity

• Docking, then activation by interleukins.
• Types of T cells include CD8 T cells that recognize and kill self-cells altered by infection.

B Cell Activation And Antibody Production

• Once B cells process the Ag, interact with TH cells, and are stimulated by growth and differentiation factors, they undergo mitosis and clonal expansion.
• Divisions give rise to plasma cells that secrete antibodies and memory cells that can react to the same antigen later.

Antibody Structure And Functions

• Immunoglobulins: large Y-shaped protein composed of 4 polypeptide chains.
• Contain 2 identical fragments (Fab) with ends that bind to a specific antigen.
• Fc binds to various cells and molecules of the immune system.

Immunoglobulin (Ig) Classes

• IgG: monomer, produced by plasma cells (primary response) and memory cells (secondary), most prevalent.
• IgA: monomer circulates in blood, dimer in mucous and serous secretions.
• IgM: five monomers (pentamer), first class synthesized following Ag encounter.

Vaccine Preparation

• Most vaccines are prepared from:
  • Killed whole cells or inactivated viruses
  • Live, attenuated cells or viruses
  • Antigenic molecules derived from bacterial cells or viruses
  • Genetically engineered microbes or microbial agents

Killed Or Inactivated Vaccines

• Cultivate the desired strain, treat it with formalin or some other agent that kills the agent but does not destroy its antigenicity.
• Often require a larger dose and more boosters to be effective.

Live Attenuated Cells Or Viruses

• Process that substantially lessens or negates the virulence of viruses or bacteria – eliminates virulence factors.
• Confers long-lasting protection, but can be transmitted to other people and can conceivably mutate back to virulent strain.

Antigenic Molecules (Vaccines From Microbe Parts)

• Acellular or subcellular vaccines (subunit – if a virus).
• Exact antigenic determinants can be used when known.

Route Of Administration And Side Effects

• Most administered by injection; few oral, nasal.
• Some vaccines require adjuvant to enhance immunogenicity and prolong retention of antigen.
• Possible side effects include local reaction at injection site, fever, allergies; rarely back-mutation to a virulent strain, neurological effects.

Herd Immunity

• Immune individuals will not harbor the pathogen, reducing the occurrence of pathogens – herd immunity.
• Less likely that a non-immunized person will encounter the pathogen.

Immunological Memory

• All antibodies are immunoglobulins composed of 4 polypeptide chains.
• Composed of 2 identical heavy chains (H) and 2 identical light chains (L) with a wide range of variable antigen binding sites.