Transcript Humorial & Cell-related immunity defend against different types of

To understand what the heck we’re talking
about, you need some background.
Early immunization theory:
When early scientists transferred fluids like plasma
and lymph (archaic term: “Humors”, therefore
“humoral” in the first slide) from one animal to
another, the second animal gained an immunity to
microbes the first animal had been exposed to.
They found that certain immunities could only exist
if T-cells were also transferred.
But what does that mean?
Therefore, there are two kinds of immunity:
Humoral immune response refers to the activation of B cells to produce Antibodies that are circulated
in the blood and lymph systems.
Defends against pathogens and toxins in extracellular fluid.
Cell-mediated immune response activates cytotoxic T cells, which directly attack and destroy target
cells.
Defends against infected cells, cancer cells, and transplanted tissues.
The whole process is initiated by Helper T cells, which identify the antigen and stimulate the two immune
responses accordingly.
HTCs use a surface protein called CD4 to bind to Class II MHC sites on antigen-presenting cells in
order to identify the antigen.
Once the antigen is identified, the HTC activates either the B Cells or the cytotoxic T cells.
http://www.youtube.com/watch?v=aSpRpf1Ny9A
More than you ever
wanted to know
about Cytotoxic T
Cells…
Cytotoxic T Cells target
MISBEHAVING cells.
•They bind to class I MHC molecules
using CD8.
•Recall: Class II MHC/CD4 and Helper T Cells.
•They destroy infected and/or
cancerous cells, which it identifies
because tumor cells carry antigens
not normally found on body cells.
•Certain cancers and viruses such as EpsteinBarr (Mono) reduce the class I MHC sites on the
cell, rendering CTCs less effective. Natural Killer
cells can take care of these no problem, though.
…And about B
Cells
•When a B cell encounters a specific antigen, it triggers a
humoral response.
•Usually this is just to bacteria or incompatible transplanted
tissues/transfused blood. In some people, however, pollen, bee venom, etc
can induce a hypersensitive reaction. This is an allergy.
•Helper T cells secrete cytokines that differentiate the B cell into
clone groups, one of antibody-secreting plasma cells, and one of
memory B cells.
•B cells are specifically effective against the one antigen they can
bind to. Each separate antigen results in a different cadre of B
cells.
•Some antigens only trigger an immune response in the presence
of Helper T cells. They are T-Dependent Antigents.
•Other antigens, like bacterial capsules and flagella trigger
antibodies without Helpter T cells. They are T-Independent
antigens.
IB Wants us to talk to you
about HIV/AIDS.
HIV (Human
Immunodeficiency Virus)
works by attacking Helper T
Cells.
This leads to a reduction of
the number of active
lymphocytes and a loss of the
ability to produce antibodies.
The effects of HIV as defined
by the IB syllabus is limited
specifically to the above.
AIDS (Acquired Immune
Deficiency Syndrome) is
defined by the presence of
one or more opportunistic
infections (ie, Kaposi's
Sarcoma) due to advanced
HIV infection.
HIV is transmitted via
exchange of bodily fluid via
sexual contact, intravenous
drug use, from mother to
child, or transplant and/or
transfusion of infected
organs and blood.
CLASS DISCUSSION TIME!
IB wants us to connect to TOK here.
From the syllabus:
6.3.8 Discuss the cause, transmission and social implications of AIDS.
Aim 8: The social implications of AIDS are well known. Cases of AIDS are
not evenly distributed in the world, and consideration could be given to the
severe problems in southern Africa. Cultural and economic reasons for
differences in the prevalence of AIDS could be considered. The moral
obligation of those with the technology and the wealth to help others
lacking these things could be discussed.
TOK: The different methods of transmission of HIV each carry their own
risk. The extent to which individuals in different societies can minimize or
eliminate each of these risks could be considered.
Monoclonal antibodies &
diagnosis
B Cells fuse to tumors and other antigens,
resulting in a proliferation of antibodies.
Detection of these antibodies is indicative of
exposure to the antigen.
Presence of HIV antibodies is use to diagnose an
HIV infection.
Drugs can be attached to monoclonal antibodies to
treat certain cancers.
Types of immunity as
defined by antibodies.
Active: Immunity due to exposure to antigens and production
of antibodies.
IE: You had chicken pox as a child, and now you are immune.
Vaccination is also considered to be “active” immunity.
Passive: Immunity due to acquisition of antibodies from
another source.
IE: Across the placenta, via Colustrum (mother’s milk), and
through injection of antibodies.
Passive immunity is temporary but allows the body time to
develop active immunity without falling under undefended attack.
Can you….?
Define ‘Pathogens’?
Explain why antibiotics work on bacteria but not viruses?
Distinguish between antibodies and antigens?
Explain antibody production?
Outline the effects of HIV on the immune system?
Explain the production of monoclonal antibodies and give one example of
diagnosis and one treatment?
Explain the difference between active and passive immunity?