Allergy Overview

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Allergy Overview
Sanjeev Jain, MD, PhD
Ste 101, 3400 SE 196th Avenue Camas, WA 98607
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There are two arms to the immune response to any
foreign substance (antigen) entering the
bodythe innate immune responsethe adaptive
immune response
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• Innate Immune Response
• rapidly deployed - first line defense
• encoded in genome - conserved from flies to
  humans
• broad recognition of microbialpatterns
• no memory of past encounter with antigen

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• Adaptive Immune Response
• exquisitely specific recognition
• of millions of different potential antigens
• requires gene rearrangement to generate
• antigen specific receptors
• long-term memory of past antigen
• encounter

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Antigen specific receptors onT cells and B cells
characterize the adaptive immune response.T
cells - cell mediated immunityB cells -
antibody mediated (humoral) immunity
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Two Arms of Cell Mediated Immunity

• There are two types of T-cells
• Th1 and Th2.
• Th1 cells produce mediators that stimulate the
  immune system responsible for defense against
  intracellular pathogens.
• Th2 cells stimulate the defense against
  extracellular pathogens and parasites.
• Th2 cells are also responsible for allergies.

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Most immune responses have both a Th1 and Th2
component. The T cell response to some
infectious agents becomes polarized to one Th
subset.
Degree of polarization
Th 2
Th2
Th1
Th 1
Helminthic Parasites (worms)
Bacteria (tuberculosis) Viruses (measles)
Helminthic parasites
Gram - negative bacteria
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How is an Allergic Reaction Triggered?
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What is Asthma

• Airway Obstruction
• Airway Hyper-reactivity

• Allergic Inflammation
• Mucus Secretion

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The Hygiene Hypothesis
Allergy and asthma have increased during the last
20-50 years due to reduced exposure to childhood
bacterial and viral infections brought about by
improvements in vaccination and sanitation. In
the absence of these Th1 polarizing stimuli
mucosal immune responses fail to overcome their
inherent Th2 bias and become slanted in the
direction of allergy.
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The relationship between infection and allergic
disease
In developing countries Low incidence of
allergic disease High incidence of infectious
diseases (Th1) High infection with worms
(helminths)
In developed countries High incidence of
allergic disease Low incidence of infectious
diseases (Th1) Low infection with worms
(helminths)
Allergic disease (Th2)
Helminth Infection (Th2)
Microbial Infection (Th1)
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Common Indoor Aeroallergens

• Dust Mites
• Microscopic Insects that live in all bedding,
  padded furniture, and carpet. They feed on dead
  skin or dander, and get water from humidity
• Mold
• Mold grows in all high humidity environment.
• Pet Dander
• All mammals and birds shed dead skin or dander
  which becomes airborne and sticks to clothing and
  furniture.

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Common Outdoor Allergens

• Tree Pollens
• Commonly present in spring between February to
  May
• Grass Pollens
• Commonly present in summer between April to
  August
• Weed Pollens
• Commonly present in fall between August to
  October

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Allergies can be controlled three ways
Avoid the allergens, the things youre
allergic to Treat the symptoms with
medications Stop the allergic reaction
with allergy shots, also known as
immunotherapy
Some of the most exciting and hopeful advances
are taking place in immunotherapy.
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Qualifications of An Allergist

• A physician who has received residency training
  in one of the primary care specialties.
• Following residency he/she has received 2-3 years
  of training in an accredited allergy fellowship
  training program.
• Allergists are expected to undergo rigorous
  testing to qualify for certification by the
  American Board of Allergy and Immunology.
• Allergists are experts in clinical immunology,
  pathophysiology of rhinitis and sinusitis
  asthma, allergic conjunctivitis, urticaria,
  angioedema, anaphylaxis, atopic dermatitis, food
  allergy, medication allergy, stinging insect
  allergy, latex allergy, mastocytosis,
  eosinophilic syndromes, aerobiology, and
  immunodeficiency.

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Who Should Receive An Allergy Consultation

• A patient whose seasonal or perennial rhinitis,
  sinusitis, or conjunctivitis is not in adequate
  control with standard medications alone.
• All asthma patients should receive consultation
  by an allergist at least once to determine if
  environmental control measures or immunotherapy
  can benefit them.
• All patients with moderate to severe asthma
  should receive at least yearly evaluation by an
  allergist or pulmonologist to ensure that their
  asthma is stable and optimal therapy is
  instituted. An allergist can also offer
  specialized therapy such as Xolair to these
  patients.
• All patients with chronic, recurrent, or
  difficult to treat urticaria or atopic
  dermatitis.

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Who Should Receive An Allergy Consultation
Conted.

• All patients with angioedema or anaphylaxis of
  unknown etiology.
• A patient who needs to have a definitive
  diagnosis of a food allergy, or wishes to be
  educated about his/her food allergy.
• A patient whose diagnosis of a medication allergy
  is uncertain, or someone who needs to be
  desensitized to a medication that he/she is
  allergic to.
• All patients who have a systemic reaction to an
  insect sting.
• Any patient who requires evaluation or treatment
  of latex allergy.
• All patients with mastocytosis, eosiniphilic
  syndromes, and other rare allergy-related
  illnesses.
• Any patient with recurrent or life-threatening or
  uncommon infections.