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Hello, my name is Sara Marshall and I'm an Honorary Professor of Clinical Immunology at
the University of Dundee and
Head of Clinical and Physiological Sciences at the Wellcome Trust.
My talk today is titled Hypersensitivity.
My objectives for this talk are firstly to
review the classification of hypersensitivity disorders,
to appreciate and describe the immunological mechanisms that
underlie the different types of hypersensitivity disorders and diseases,
and to describe how
these different immunological mechanisms
influenced treatment options for these conditions.
First of all, let's define what a hypersensitivity reaction is.
The classic definition is that a hypersensitivity reaction is
an immune response that results in bystander damage to the self.
It's usually an exaggeration of normal immune mechanisms.
It's the important pathophysiological basis for many diseases,
including the diseases of allergy and autoimmunity.
Let's just start with the fundamental question which is, does autoimmunity exist?
You may wonder why we asked this question at all.
But, at the beginning of the 20th century,
it was thought that autoimmunity was impossible.
Ehrlich who went on to get the Nobel Prize found that
he was unable to immunize animals against self tissue.
He surmised that autoimmunity was, in fact,
impossible and he described it as "horror autotoxicus."
Now in the 1940s-1950s,
it became clear that autoimmunity did, in fact,
occur and was present in some human diseases.
Now, the first autoimmune disease to be described was autoimmune hemolytic anemia,
where the autoimmunity is against red blood cells.
Subsequently, with Witebsky and Rose,
Witebsky was a student of Ehrlich's and they described that immunization of rabbits
with a rabbit hormone would result in antibodies and inflammation.
Now, things have progressed since then, and at the moment,
we think that up to 5 percent of the population is affected by an autoimmune disease.
These conditions that are associated with hypersensitivity reactions are very common.