Innate and Adaptive Immunity
•
•
•
•
•
•
•
Innate immunity leads to diverse responses to a pathogen
the innate immune system consists of cells and proteins that are always present
and ready to mobilize and fight microbes at the site of infection
the main components of the innate immune system are 1)physical epithelial
barriers, 2)phagocytic leukocytes, 3)dendritic cells, 4)a special type of lymphocyte
called a natural killer (NK) cell, and 5) circulating plasma protein
Adaptive immunity helps defends against viruses.
Antigens are molecules that provoke a specific immune response and are a large
part of adaptive immunity.
Characterized by specificity of recognition of antigen, wide diversity of antigens
can be specifically recognized, memory, where by the immune system respond
more quickly and more intensely to an antigen it encountered previously than to
one it is meeting for the first time, and the ability to distinguish self-antigens
from nonself
The adaptive immune system can be active or passive
Cells of the Immune System
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Helper T cell: recognizes foreign peptides on antigen-presenting cells, inducing the release of cytokines
that activate b cells or macrophages
Cytotoxic T cell: recognizes and kills "altered self" cells: virally infected, or tumor cells
B cell: binds specific soluble antigens with its membrane-bound antibody; serves as an antigen-presenting
cell to Th cells; on activation differentials into plasma and memory B cells
Plasma cell: derived from activated B cells; is a biochemical factory devoted t0 the secretion of antibodies
directed against specific antigens
Natural killer cell: Rapidly recognizes and kills virally infected cells or tumor cells
Monocyte: precursor of macrophage; located in blood system
Macrophage: phagocytic tissue cell that is a component of the body's first cellular line of defence; found in
large numbers in the blood until attracted to tissues during inflammation
Eosinophil: Important to the elimination of parasites and involved in chronic inflammatory diseases
Basophil: Circulating cell that releases mediators such as histamine that promote inflammation
Mast cell: located primarily under mucosal surfaces and releases mediators such as histamine that
promote inflammation; triggered both during inflammatory and allergic reactions
Dendritic cell: important antigen-presenting cell naive Th cells; also helps in the activation of naive Tc cells
Cell-Mediated Immunity
• T cells may be characterized as either
•
•
cytotoxic T cells or helper T cells
cytotoxic T cells eliminate virally infected cells
and tumor cells
Cytotoxic T cells destroy cells in a fashion
similar to NK cells; it secretes perforin
monomers that creates pores in the target's
membrane, then granzymes enter and
activate caspases which cause the apoptosis
(destruction) of the target
Humoral Immunity
•
•
•
•
•
•
•
B cells are activated by membrane Ig molecules binding to a specific epitope on
an antigen
Immunoglobulins consist of two light chain and two longer heavy-chain
polypeptides
Antibodies can agglutinate, precipitate, or neutralize antigens
The five classes of immunoglobulins that determine function: IgA, IgD, IgE, IgG, &
IgM
The secondary response to an antigen is more effective than the primary
response
A rapid secondary response is launched due to memory cells
Flu shots/vaccination (presents the body with an antigen to elicit the primary
response, then when encountered again, a pathogen is eliminated quickly by the
secondary response
Antibody Production
• Each plasma B cell is a miniature factory
•
•
producing soluble antibodies of the same
specificity as the membrane-bound
antibodies of the parent B cell
The variable regions of the heavy and light
chains fold together to form a cleft, the
antigen binding site
The five classes of antibodies are based on
the sequence and structure of the constant
regions of their heavy chains
True and False
1.
1. Adaptive immunity provokes a specific immune response and is large part of the
innate immunity
False
1. Cytotoxic T cells recognize foreign peptides on antigen-presenting cells, inducing
the release of cytokines that activate b cells or macrophages
False
1. T cells may be characterized as either cytotoxic T cells or helper T cells
True
1. A primary response is more effective than the secondary response
False
1. The variable regions of the heavy and light chains fold together to form a cleft,
the antigen binding site
True
Multiple Choice
1.
1. The five classes of immunoglobulins are:
A: IgA, IgD, IgE, IgG, IgM
B: IgA, IgC, IgD, IgE, IgF
C: IgA, IgD, IgE, IgG, IgH
D: IgB, IgD, IgE, IgG, IgF
Answer: A
Here is a video explaining how the
immune system works!