Overview
of Immunology - From Chapter 1
Innate
Immunity or Natural Immunity:
General Immune
Mechanisms:
Physical Barriers –
skin, fluids, mechanical forces
Chemical Barriers – pH,
salt, fatty acids, lysozyme
Complex Biochemical
Pathways and Mechanisms
o
Fever
o
Phagocytosis
o
Inflammation
o
Complement
o
Toll-like receptors
Acquired
Immunity:
Only vertebrates
Specificity -->
It is induced by and adapts to antigen -- there is recognition of
"foreign" versus "self". The triggering event is called immunization – if it is done as a medical procedure it is often called
vaccination. The triggering substance is called antigen.
Lymphocytes (B-cells and T-cells) are "activated"
--> this means that they are induced to divide and secrete compounds. B-cells make and secrete antibody. Some T-cells
secrete cytokines, some T-cells
seek out and kill target cells on contact.
There
is memory. This often called an anamnestic response
There is the ability to respond to previously unseen
molecules
Acquired immunity
can be classified as:
Active
Passive
Adoptive
What
is the mechanism of acquired immunity?
Clonal Selection
--> See Figure 1.1
The
cell surface receptors on B-cells and T-cells are highly specific in terms of what they bind or recognize . The B-cell receptor (BCR) is called antibody. The T-cell receptor is usually abbreviated as the TCR. A more general or non-specific set of cell surface
receptors called major histocompatibility complex (MHC) molecules are
found on the surface of antigen presenting cells (APC’s).
A repertoire of lymphocytes with a myriad of specificities
exists before antigen ever enters
the system. When and how antigen
encounters the system is important – under certain circumstances it may
actually turn off the response.
This is called tolerance.
In general, a bodies immune
system is tolerant of its “self-antigens”, if this property disintegrates, autoimmunity results
Binding to antigen
(Lock and Key). The B-cell or the
T-cell receptor latches onto a small part or epitope of the antigen molecule
Triggering cells to
divide and proliferate. Clones of cells
arise from each cell that initially interacted with antigen. Note that within a clone all the cells
are identical.
Some of these cells
will be effector cells which secrete
substances;
*
B-cells secrete antibody
*
T-cells secrete cytokines (TH cells) and perforin (TC cells)
Some of these cells
will be Memory Cells
Humoral Immunity –
Soluble Immunity
Discuss Antibody
structure: Fab and Fc regions, H-chains and L-chains. See figure 1.2.
Cell Mediated
Immunity
• Discuss the TCR
and T-cell subtypes:
• TH
--> TH1 and TH2 cells
• TC
cells
• T-cells don't
recognize antigen directly --> antigen needs to be "presented"