HYPERSENSITIVITY & ALLERGY

1
(No Transcript)
2
ALLERGY HYPERSENSITIVITY
Dr. Muhammad Muqeem Mangi
Associate Professor,
Physiology Suleman Roshan Medical Medical
College, Tando Adam, Sindh, Pakistan
3
DELAYED REACTION

• THE DELAYED REACTION ALLERGY APPEARED BY
  ACTIVATED T CELL
• IN TOXIN OF POISON IVY IT ITSELF IS NOT POISON ,
  DOEST NOT GIVE ANY HARM .
• BUT ON REPEATED EXPOSER IT DOES CAUSE THE
  ACTIVATION OF HELPER AND CYTOTOXIC T CELLS
• WITH CONTINUE EXPOSURE WTHIN A DAY THE ACTIVATED
  T CELL ATTRACT AND DIFFUSE FROM CIRCULATION TO
  SKIN IN HUGE NUMBER.
• SUCH ACTIVATION CAUSES TO PRODUCE VERY LETHAL
  TOXIC SUBSTANCES FROM T CELL AND ACTIVATED
  MACROPHAGES
• AND SUCH DELAYED REACTION CAUSES THE DAMAGE OF
  TISSUES

4
CONT DELAYED REACTION

• DAMAGE OCCUR IN THE TISSUES WHERE THE CAUSITIVE
  INSTIGATING ANTIGEN IS PRESENT .
• THE TISSUES THE SKIN OR LUNGS CAUSES EDEMA AND
  ASTHMA

5
ATOPIC ALLERGIES ASSOCIATED WITH EXCESS IGE
ANTIBODIES

• THE PEOPLE WHO HAVE ALLERGIC TEDENCY ARE CALLED
  ATOPIC ALERGY.
• BCZ ITS NONORDINARY RESPONSE PASSING GENETICALLY
• FROM PARENTS TO CHILDRENS,
• CHARACTERISED BY PRODUCING LARGE QUANTITIES OF
  IgE ANTIBODIES IN THE BLOOD.
• THE ANTIBODIES ARE CALLED REAGINS OR SENSITIZING
  ANTIBODIES

6
CONT ATOPIC ALLERGIES ASSOCIATED WITH EXCESS
IGE ANTIBODIES

• THESE REAGINS MEANS IgE ARE DISTINGUISH THEM FROM
  THE MORE COMMON IgG
• WHEN AN ALLEGEN ENTER IN THE BODY AN ALLERGEN-
  REAGIN REACTION OCCUR
• ANTIGEN REACT ALWAYS WITH SPECIFIC TYPE OF IgE

7
CONT ATOPIC ALLERGIES ASSOCIATED WITH EXCESS
IGE ANTIBODIES

• THESE IgE HAVE HABBIT TO ATTACH TO MAST CELLS AND
  BASOPHIL.
• A SINGLE MAST CELL AND BASOPHIL ATTACHED OR BIND
  HALF A MILLION MOLECULES OF IgE.
• THIS CAUSES IMMEDIATE CHANGE IN THE MEMBRANE OF
  CELLS DUE TO PHYSICAL EFFECT OF ANTIBODIES TO
  DEFORM THE CELL MEMBRANE .
• MANY MAST AND BASOPHIL RUPTURE, AND OTHER
  RELEASES SPECIAL AGENTS

8
CONT ATOPIC ALLERGIES ASSOCIATED WITH EXCESS
IgE ANTIBODIES

• THE SUBSTANCES RELEASES SOON AFTER RUPTURING THE
  CELLS
• HISTAMIN
• PROTEASE
• SLOW REACTING SUBSTANCES OF ANAPHYLAXIS ( MIXTURE
  OF TOXIC LEUKOTRIENES).
• EOSINOPHIL AND NEUTROPHIL CHEMOTACTIC SUBSTANCES
• HEPARIN .
• AND PALTELETS ACTIVATING FACTORS,
• THESE CAUSES EFFECTS AS FOLLOW

9
CONT ATOPIC ALLERGIES ASSOCIATED WITH EXCESS
IgE ANTIBODIES

• THESE SUBSTANCES EFFECT TO CAUSE
• DILATATION OF LOCAL BLOOD VESSELS.
• ATTRACTION OF EOSINOPHIL AND NEUTROPHIL TO
  REACTIVE SITE.
• INCREASE PERMEABILITY OF THE CAPILLARIES WITH
  LOSS OF FLUID INTO THE TISSUES
• AND CONTRACTION OF LOCAL SMMOTH MUSCLE CELLS
  APPEAR.
• SO THE SEVERAL DIFFERENT TISSUE RESPONSES APPEAR
  .
• DEPENDING THE TYPE OF TISSUE IN WHICH THE
  ALLERGEN REAGIN REACTION APPEAR.

10
Anaphylaxis

• WHEN A SPECIFIC ALLERGEN INJECTED DIRECTLY IN THE
  CIRCULATION
• IT WILL REACT WITH MAST CELLS AND BASOPHIL CELL
  IMMEDIATELY OUTSIDE BLOOD VESSELS
• WIDESPREAD REACTION OCCUR THROUGH OUT THE
  VASCULAR SYSTEM
• THIS REACTION IS CALLED ANAPHYLAXIS
• SOME TIME CAUSES DEATH DUE TO SUFFOCATION ,
  APPEAR DUE TO LEUKOTIENS SUBSTANCES AND SLOW
  REACTING SUBSTANCES OF ANAPHYLAXIS CAUSES SPASM
  OF SMOOTH MUSLES OF BRONCHIOLES,
• ELICITING ASTHMA LIKE ATTACH

11
(No Transcript)
12
(No Transcript)
13
UTRICARIA

• ITS REACTION OF ANTIGEN IN THE SKIN MEANS
  LOCALIZE REACTION OCCUR
• BY RELEASING HISTAMIN
• IT CAUSES VASODILATION THAT INDUCE AN IMMEDIATE
  RED FLARE AND,
• INCREASE LOCAL PERMEABILITY OF THE CAPILLARIES
  THAT LEADS TO SWELLING OF THE AREAS OF THE SKIN
  WITHIN A MINUTE
• THE SWELLING ARE CALLED HIVES

14
(No Transcript)
15
HAY FEVER

• THIS FEVER APPEAR DUE TO REACTION OF ALLEGEN
  REAGIN IN THE NOSE
• IN RESPONSE OF REACTION HISTAMINE RELEASED CAUSES
  
• LOCAL INTRNASAL VASCULAR DILATION WITH INCREASE
  CAPILLARY PRESSURE AND INCREASE PEMEABILITY
• BOTH EFFECTS CAUSE RAPID FLUIED LEAKAGE, IN NOSE
  AND DEEPER TISSUES OF NOSE .
• OTHER ALLERGEN REAGIN REACTION SECRETION ALSO
  CAUSES IRRITATION OF NOSE , PRODUCE THE TYPICAL
  SNEEZING SYNDROME

16
(No Transcript)
17
ASTHMA

• ITS ALSO MENIFEST IN ALLERGIC PERSON
• THE ALLEGEN-REAGIN REACTION OCCURS IN BRONCHIOLES
  OF THE LUNGS
• HERE AN IMPORTANT PRODUCT RELEASE FROM MAST CELLS
  THAT MAY BELIEVE TO BE SLOW REACTING SUBSTANCE OF
  ANAPHYLAXIS
• WHICH CAUSES SPASM OF BRONCHIOLAR SMOOTH MUSCLE
• UNTIL EFFECTS REMAIN OF REACTIVE PRODUCT

18
(No Transcript)
19
Allergy 
The term allergy was originally defined by
Clemens Von Pirquet as an altered capacity of
the body to react to a foreign substance, which
was an extremely broad definition that included
all immunological reactions.  Allergy is now
defined in a much more restricted manner as
disease following a response by the immune
system to an otherwise harmless antigen. Allergy
is one of a class of immune system responses that
are termed hypersensitivity reactions. These are
harmful immune responses that produce tissue
injury and may cause serious disease.
Hypersensitivity reactions were classified into
four types by Coombs and Gell Allergy is often
equated with type I hypersensitivity
(immediate-type hypersensitivity reactions
mediated by IgE), and will be used in this sense
here.
20
Undesirable reactions produced by the normal
immune system.
Hypersensitivity is an exaggerated immune
response that results in tissue damage and is
manifested in the individual on a second or
subsequent contact with an antigen. Hypersensitiv
ity reactions can be classified as either
immediate or delayed. Clearly immediate reactions
appear faster than delayed ones, but the main
difference between them is the nature of the
immune response to the antigen.
21
Allergy Allergies, also known as allergic
diseases, are a number of conditions caused by
hypersensitivity of the immune system to
something in the environment that usual y causes
little or no problem in most people. These
diseases include hay fever, food all
ergies, atopic dermatitis, allergic asthma, and
anaphylaxis . Symptoms may include red eyes, an
itchy rash, runny nose, shortness of breath,
or swell ing.
22

• General Features
• Hypersensitivity reactions can be elicited by
  exogenous environmental antigens or endogenous
  self antigens.
• Results from failure of normal regulation of
  immune response.
• Development of hypersensitivity diseases is often
  associated with the inheritance of particular
  susceptibility genes.

23
Types Of Hypersensitivity reactions are divided
according to mechanism of action into four
groups

• 1-Type I (Immediate hypersensitivity).
• 2-Type II (Cytotoxic hypersensitivity).
• Type III (Immune complex hypersensitivity).
• Type IV (Cell -mediated or Delayed
  hypersensitivity).
• 5-Type V(Stimulatory Type) Jones-Mote Reaction
  (or) Cutaneous Basophil Hypersensitivity

24
Type I Hypersensitivity ( IgE DEPENDENT )
A type I hypersensitive reaction is induced by
certain types of antigens referred to as
allergens, and has all the hall marks of a
normal humoral response. Allergic reactions
occur when an individual who has produced IgE
antibody in response to an innocuous antigen
(allergen) subsequently encounters the same
allergen. Type I, or anaphylactic, reactions
often occur within 2 to 30 minutes after a
person sensitized to an antigen is re-exposed to
that antigen.
25
(No Transcript)
26
Type II Hypersensitivity ( Cytolysis And
Cytotoxic) . These reactions involve a
combination of IgG (or IgM) antibodies with an
antigenic determinants on the surface of cells.
Antibody can activate the complement system,
creating pores in the membrane of a foreign cell,
or it can mediate cell destruction by antibody
dependent cell - mediated cytotoxicity (ADCC).
Type II hypersensitivity is general y, called
cytolytic or cytotoxic reactions because it
results in the destruction of host cells,

either by lysis or toxic
mediators. Type II hypersensitive reactions
involve antibody-mediated destruction of cell s
27
Type II hypersensitivity
28
Type III HypersensitivityImmune Complex-
Mediated Type III reactions involve antibodies
against soluble antigens circulating in the
serum. The antigen-antibody complexes are
deposited in organs and cause inflammatory
damage. The tissue damage that results from the
deposition of immune complexes is caused by the
activation of complement, platelets and
phagocytes in essence, an acute inflammatory
response
29
Immune complex-mediated hypersensitivity. (1)
Immune complexes on the basement membrane of the
wall of a blood vessel, where they (2) activate
complement and attract inflammatory cells such
as neutrophils to the site. (3) The neutrophilis
discharge enzymes as they react with the immune
complexes, resulting in damage to tissue cells
30
Type IV HypersensitivityDelayed Hypersensitivity
Type IV hypersensitivity reactions (delayed
hypersensitivity) constitute one aspect of
cell-mediated immune response and are caused
mainly by T cells. These are typically provoked
by intracellular microbial infections or
haptens like simple chemicals applied on the
skin, evolve slowly and consist of a mixed
cellular reaction involving lymphocytes and
macrophages in particular. It is named delayed
hypersensitivity because it appears in 24 to 48
hours after the presensitized host encounters the
antigen, while immediate hypersensitivity
reactions develop in 1/2 to 12 hours..
31
CONT Type IV HypersensitivityDelayed
Hypersensitivity Type IV hypersensitivity
reactions (delayed hypersensitivity)
A major factor in the delay is the time required
for the participating T cells and macrophages to
migrate to and accumulate near the foreign
antigens. The T cells involved in delayed type
hypersensitivity reactions are primarily TD
cells. In some types of hypersensitivities
resulting in tissue damage, Tc cells may also
participate
32
Type IV (delayed or cell -mediated)
hypersensitivity
33
(No Transcript)
34
Type V Hypersensitivity (Stimulatory Type)
Jones-Mote Reaction ( or) Cutaneous Basophil
Hypersensitivity
This is an antibody-mediated hypersensitivity and
is a modification of type Ihypersensitivity
reaction. Antibodies interact with antigens on
cell surface which leads to cell proliferation
and differentiation instead of inhibition or
killing. Antigen-antibody reaction enhances the
activity of affected cell . Example of Graves
disease Thyroid hormones are produced in excess
quantity in graves disease. Long acting thyroid
stimulating (LATS) antibody is an autoantibody to
thyroid membrane antigen. It is presumed that
LATS combines with a TSH receptor on thyroid
cell surface and brings about the the same
effect as TSH resulting in excessive secretion
of thyroid hormone.
35
(No Transcript)
36
Thank You
Histamine