Acquired Immunity: Humoral Response
• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
Acquired Immune System – Third Line of Defense
The Acquired Immune System is:
 Antigen specific – recognizes and acts against
particular foreign substances
 Discerning -Recognizes “self” from “non-self”
 Systemic – not restricted to the initial infection site
 Has memory – recognizes and mounts a stronger
attack on previously encountered pathogens
Types of Acquired Immunity
1. Humoral immunity
• Antibody-mediated
immunity in blood
and lymph
• Cells produce
chemicals for
defense
2. Cellular (adaptive)
immunity of the cellmediated immune
system
• Cell-mediated
immunity
• Cells target virally
infected cells
Acquired Immunity: Humoral Response
• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
Antigens (Nonself)
 Antigen: Any substance capable of
exciting the immune system and
provoking an immune response
Antigens
 Examples of common antigens
• Foreign proteins
• Nucleic acids
• Large carbohydrates
• Some lipids
• Pollen grains
• Microorganisms
 Antigenic determinants:
substances on the surface of
antigens to which the immune
system actually responds
Antigen
Receptor in the immune
system that "fits" the
antigenic determinant
Haptens Can Become Antigenic
Haptens are small molecules that cannot elicit an antibody
response. They can combine with carrier molecules within the
body (like proteins) and become antigenic.
• Metals (e.g. nickel in jewelry), rubber, glue, preservatives,
urushiol/quinone in poison ivy, halothane (anesthetic), some
penicillin derivatives
Self-Antigens: MHC Proteins
 Human cells have many
surface proteins called
major histocompatability
complexes (MHC).
 All body cells have MHC
“name-tag” proteins to
identify them as belonging to
your body (MHC Class I
proteins)
 Cells of the immune system
additionally have their own
tags called MHC II
proteins (“security badges”)
 Our cells in another person’s body can
trigger an immune response because they
are foreign; restricts donors for transplants
Acquired Immunity: Humoral Response
• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
Development of Lymphocytes
•Developing immunocompetence
Positive selection: finding lymphocytes whose receptors bind to foreign antigens
Negative selection: killing lymphocytes with receptors to “self” antigens like MHCs
T cell maturation
and "education"
Acquired Immunity: Humoral Response
• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
B Cell Receptors, T Cell Receptors, and Immunoglobulins
T cell
B cell
Antigen Receptors on T Cells
Receptors on B cells
Constant
regions
Variable
(binding)
regions
Secreted (Exported)
Immunoglobulin or Antibody
(Same V and C Regions as in B cell
receptors)
Immunoglobulins and Receptors Bind To Antigens
Agglutination of antigens
Different Classes of Antibodies
Any particular B cell always produces the same variable regions in its antibodies but it may change
the “constant” stem region. Stems come in five types: A, D, E, G, and M
Acquired Immunity: Humoral Response
• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
Acquired Immunity: Humoral Response
• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
B Cell Activation and Clonal Selection
Humoral
immunity
movie
T cells are also activated by clonal selection during exposure to an antigen.