Download Immunity and the Immune System

Immunity :
The Immune system plays a role in combating infection, creating
inflammation (& consequently heart disease), controlling (or
not) cancer and in auto-immune diseases.
Immune modulator molecules or cytokines and leukotrienes
which are produced by the immune system can interact with
most cells of the body
The immune system consists of organs, vessels, and cells that
can be specific to a particular organism or “antigen” or nonspecific. Some cells can identify foreign or damaged cells or
microbes, others can kill in various ways.
Organs and cells of the Immune System
 Organs of the immune system
include the bone marrow where
white blood cells are differentiated,
the lymphoid organs (spleen, tonsils,
appendix, lymph nodes) where
lymphocytes live, and he lymphatic
vessels where lymph is found.
 Cells of the immune system include
lymphocytes (many types), other
white blood cells (neutrophils,
basophils, and eosinophils),
macrophages (found everywhere),
and other dendritic cells.
Non-Specific immunity
White Blood cells
 Lymphocytes of the immune system in transit (20%)
 Macrophages (the “eaters” of the immune system in transit) as
monocytes (8%)
 Neutrophils one of he best “eaters” of bacteria (70%) They leave
blood vessels under signals from other immune system cells
like macrophages
 Other cells of the immune system such as basophils and
eosinophils which has granules in their cytoplasm they can
exocytose containing heparin and histamine (basophils) or toxic
lysosome contents (eosinophils)
The Lymphatic System
The lymphatic
system is the
body’s
surveillance
system .
It is made up of
lymph nodes
connected by
vessels that have
lymph flowing in
them, and
lymphoid organs.
Lymph
enters the
vessels in
the tissues
all over the
body as
more plasma
leaves
arteries than
enters veins.
Lymph
vessels have
valves to
prevent
backflow
In addition to lymph
nodes there are other
lymphoid tissues that
guard entry or transition
such as tonsils or
appendix
The spleen filters blood through lymphocytic
tissue and also through screening for red blood
cell damage or decay
Thymus is a
gland that is
larger in
children--- it
matures Tcells
Lymph nodes
have entry and
exit vessels and
pathways where
the fluid flows
through large
numbers of
lymphocytes
Lymphocytes:
cells of the specific immune system
Surveillance, intelligence, antibody
production and cytotoxic killers
•Three main types of lymphocytes are T-cells and B-cells.
•10% are NK cells
•15% are B-cells make antibodies
• 80% T-cells are cytotoxic killer cells, control of the immune response
(suppressor T-cells), and the coordinators of the immune response
(helper T-cells)
Lymphocytes are made in
bone marrow from stem cells
and matured either in bone
marrow (B-cells) or in the
thymus (T-cells)
Membrane Proteins and Lymphocytes
All cells make proteins
called major
histocompatitibity
proteins (MHC) that pick
up fragments of peptides
and places them in the
membrane.
This allows the immune
system to recognize that
the cell is
(a) self and
(b) normal, not infected,
malignant or damaged.
Membrane Proteins and Lymphocytes
Some cells, such as
macrophages, can
eat bacteria or other
microbes and break
them up.
They make MHC
Class II proteins
which can “present”
the antigen in the
membrane for
lymphocytes to “see”
it.
Lymphocytes (1) Natural Killer cells
Lymphocytes (2) Antibody producing B-cells
B-cells have receptors (IgD) in their
membranes where they can bind
antigens.
An antigen is a small fragment of a
protein or lipoprotein from an organism
or other invader (or from a cat saliva
protein)
The B-cell takes in the antigen and
makes an MHC class II protein
containing the antigen that can then be
“presented” to a helper T-cell which will
confirm that it is an invader or other
undesirable
B-cell Activation to make antibodies, another
view
Antibodies: what can they do?
Figure 14.13c
Figure 14.13e
Table 14.2
Figure 14.14
Lymphocytes (3) T-cells
•There are 2 main types of T-cells
identified by membrane markers CD4
and CD8.
•All T-cells and B-cells make memory
cells
•CD8 T-cells are killer T-cells and
suppressor T-cells
•CD4 T-cells are Helper T-cells
CD8 T-cells
CD8 cells activation
CD4 T-cells
CD4 cell activation
Helper Tcells
coordinate
the
immune
response
Overview
of the
Immune
Response
Fig. 22-25, p. 796
Response to infection
How Vaccines work
 Exposure to a part of an organism, an attenuated organism or a
tiny dose of live organism stimulates the immune system to form
memory cells
 Some response needs more than one exposure to get good
coverage (examples are hepatitis B, human papilloma virus)
Fig. 22-22a, p. 794
Fig. 22-22b, p. 794
Mechanism of
Allergy and
Anaphylaxis
Fig. 22-26, p. 801