Immuno Hypersensitivity Reactions Type I II III IV Tutorial: Allergy, Histamine, Antibody,

Uploaded by helphippo on 02.09.2012

ABCD as Four types of hypersensivity reactions.
Type I is “Allergy.” First time you get stung by a bee - no big
deal - your immune system has been sensitized to bee venom and makes antibodies.
Which is fine, if the antibodies are NOT IgE.
If you're unlucky, the second time you get stung, you start overproducing IgE,
which causes over-release histamine and other mediators.
This causes swelling and airway constriction. So you can't breath, unless you get a shot
of adrenaline.
You may remember adrenaline as “Fight or Flight” -
so it relaxes airways, providing more oxygen to better run from tigers.
So adrenaline also helps relax airways when you've got an allergic reaction.
Type II is Bad Blood transfusion - cytotoxicity. If you have type B blood, but get a type A
transfusion, your body will use antibodies to kill... cells
with A's on them.
Type III is “Clumps of the Arthus reaction.” Back in 1900, Dr. Arthus injected rabbits
with horse serum, and “magic clumps” formed. Today we know those “magic clumps” are
rabbit antibodies bound to foreign horse proteins.
Sometimes, humans get “magic clumps” when we only make “enough antibody” to bind
to the antigen, but “not enough antibody” to get rid of
the antigen.
These “magic clumps” cause problems when they settle in joints, or in the small blood
vessels in the kidney.
Type IV is “Delayed” and cell mediated. You have bad bone marrow, so you get a donor.
If the donor is not well-matched to your body, tis “bone marrow” graft will make T-cells
that don't recognize your host cells and start attacking them.
It takes time for “his T-cells” to mature and start attacking - which is why this is
a “delayed” hypersensitivity.
Also, it involves big killer T-cells, NOT small antibody proteins, so it is “Cell
Pause and review: 4 types of hypersensitivity.
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