16 Questions
What is the physiologic function of humoral immunity?
Defense against extracellular microbes and microbial toxins
Which type of immunity is mediated by T lymphocytes?
Cell-mediated immunity
What types of microorganisms are combated by humoral immunity?
Extracellular bacteria, fungi, and even obligate intracellular microbes
Defects in antibody production can result in increased susceptibility to infection with which types of microbes?
Bacteria, fungi, and viruses
Apart from their protective roles, how can antibodies be harmful?
Mediate tissue injury in allergic individuals, autoimmune diseases, blood transfusion reactions, and transplant rejection
Which form of adaptive immunity can be transferred from immunized to naive individuals with serum that contains antibodies?
Humoral immunity
What are the main functions of antibodies?
To neutralize and eliminate infectious microbes and microbial toxins
Where are antibodies produced in mucosal organs such as the intestine and the airways?
In the lamina propria
Which two enzymes can be used to identify the different functional parts of antibodies?
Papain and pepsin
What does the term 'affinity' refer to in the context of immunoglobulins?
The individual interaction of antibody and antigen
Which cells differentiate in germinal centers of lymph nodes by isotype switching into plasma cells that secrete IgA, IgG, or IgE?
Mature B cells
What instructs the B lymphocyte to undergo isotype switching, changing the heavy-chain constant domains to classes of antibodies with new and different effector functions?
Helper T cells
What happens to the excised DNA during isotype switching in B lymphocytes?
It gets degraded
Why is IgM the principal immunoglobulin of the primary immune response?
Because it is replaced in later responses by antibodies of different isotypes
When are IgM antibodies occasionally produced during secondary and later immunologic responses?
At low levels
What does idiotype refer to in the context of antibody molecules?
The unique variable regions determining antigenic specificity
Study Notes
Humoral Immunity
- Physiologic function of humoral immunity is to combat extracellular microorganisms, such as bacteria, viruses, and fungi, through the production of antibodies.
Cell-Mediated Immunity
- T lymphocytes mediate cell-mediated immunity.
Microorganisms and Humoral Immunity
- Humoral immunity combats extracellular microorganisms, such as bacteria, viruses, and fungi.
Defects in Antibody Production
- Defects in antibody production can result in increased susceptibility to infection with extracellular microorganisms, such as bacteria, viruses, and fungi.
Harmful Effects of Antibodies
- Apart from their protective roles, antibodies can be harmful by causing autoimmune diseases, allergic reactions, and serum sickness.
Adaptive Immunity Transfer
- Passive adaptive immunity can be transferred from immunized to naive individuals with serum that contains antibodies.
Functions of Antibodies
- Main functions of antibodies are to neutralize toxins, agonize pathogens, and mark pathogens for destruction.
Antibody Production in Mucosal Organs
- Antibodies are produced in mucosal organs such as the intestine and the airways by plasma cells in the mucosal lymphoid tissues.
Identification of Antibody Parts
- Two enzymes, papain and pepsin, can be used to identify the different functional parts of antibodies.
Affinity of Immunoglobulins
- The term 'affinity' refers to the strength of binding between an immunoglobulin and an antigen.
Isotype Switching
- B lymphocytes differentiate in germinal centers of lymph nodes by isotype switching into plasma cells that secrete IgA, IgG, or IgE.
Isotype Switching Instruction
- Cytokines instruct the B lymphocyte to undergo isotype switching, changing the heavy-chain constant domains to classes of antibodies with new and different effector functions.
Isotype Switching Process
- During isotype switching in B lymphocytes, the excised DNA is circularized and deleted.
Primary Immune Response
- IgM is the principal immunoglobulin of the primary immune response because it is the first antibody produced in response to an initial infection.
Secondary Immune Response
- IgM antibodies are occasionally produced during secondary and later immunologic responses, especially when there is a large amount of antigen present.
Idiotype
- Idiotype refers to the unique antigenic determinants present on the variable regions of an antibody molecule.
Test your knowledge on humoral immunity, including primary and secondary immune responses, antibodies, and class switching. Learn about the physiologic function of humoral immunity in defense against extracellular microbes and microbial toxins.
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