Allergic to Dogs and Allergies in Dogs Resource

Antibodies (Immunoglobulins), Hypersensitivity and Allergies

What are Antibodies (Immunoglobulins)?

Antibodies are also known as Immunoglobulins (Ig). These are proteins produced by the immune system’s plasma cells (type of white blood cell) in response to antigens.

Lymphocytes (type of WBC)
B-cells (type of lymphocyte that produce antibodies)
Plasma cells (type of B-cell)
a.k.a. plasma B cells or plasmocytes
Placental mammals such as humans and dogs have 5 categories of antibodies which include

IgA,  IgD,  IgE,  IgG and IgM.


IgE is of particular importance regarding the issue of allergies. When allergens and IgE bind, it triggers specialized cells (mast and basophiles) to release various inflammatory chemical mediators such as histamine, resulting in the symptoms associated with an allergy response. IgE is not only associated with allergies and microbial/parasitic infections but also autoimmune diseases (Dimson et al.2003) and anti-tumoral defense (Gould et al.1999).

Antibodies (Immunoglobulins), Hypersensitivity and Allergies

What is Hypersensitivity?

Dogs and humans have immune systems that aim to protect them against foreign substances and disease. Hypersensitive reactions can occur when the immune system of a pre-sensitized individual overreacts and mounts an amplified response when re-exposed to a substance. Though traditionally viewed as detrimental responses, hypersensitivity reactions can also be considered as a host-protective (Rajan 2003) such as through helping to isolate and eliminate specific antigens.

Hypersensitive reactions are immune-mediated responses that range in severity from the mild, albeit irritating or uncomfortable (common), through to damaging (less common) and severe/anaphylaxis (relatively rare) or even fatal (rare).

Alloimmunity, Autoimmunity and Hypersensitivity

Alloimmunity is the term used to describe an immune response directed to antigens from the same species e.g. grafts and transplant rejections.

Autoimmunity refers to when the immune system mounts a response against its own cells and tissues e.g. rheumatoid arthritis and allergies.

Hypersensitivity refers to an undesirable reaction by the immune system with an outcome that is detrimental to the body. Allergic reactions represent an undesirable immune response and are grouped by ‘type’. Type 1 Hypersensitivity is associated with the ‘classic’ allergy response; it represents what people typically think of as “having an allergy” and includes aspects such as atopy, anaphylaxis and allergic asthma.  

Hypersensitivity Types and Characteristics

Classification of hypersensitivity into various ‘types’ is achieved based on factors such as the underlying mechanism and mediators involved (e.g.  IgE, IgG, IgM, T-cells), as well as the severity and latency of the response.  Although the 4 type model advocated by Gell and Coombs in 1963 is still most widely used, variations do exist between authorities.

4 Type Model (Gell and Coombs):

   TYPE 1  TYPE 2  TYPE 3  TYPE 4
Immediate Hypersensitivity
Atopic, Anaphylactic or Reaginic Allergy
Cytotoxic Hypersensitivity
Immune Complex-Mediated Hypersensitivity  Cell-Mediated Hypersensitivity
Delayed Type Hypersensitivity
Acute Response:
Seconds – Minutes

Late-Phase Response:
2 – 24 hours

 Minutes – Hours  Hours – Day  2 – 3 days

Chemotherapy drugs

Dog allergens

Food  allergy

Hay fever

Types of symptom:

Angioedema (swelling)
Pruritis (Itchiness)
Urticaria (hives)
and is associated with atopy (genetic predisposition to produce IgE following allergen exposure), allergic asthma, allergic rhinitis, atopic dermatitis and anaphylaxis

Erythroblastosis fetalis

Goodpasture’s syndrome

Membranous nephropathy

Transfusion reactions

Widespread, systemic diseases for example:

Farmer’s Lung (Hypersensitivity pneumonitis)

Rheumatoid arthritis

Serum sickness  

Systemic lupus erythematous

Allergic contact dermatitis related to allergens such as to poison ivy (as opposed to chemical-related skin
damaged inflammation termed
‘irritant contact dermatitis’ or sometimes simply ‘contact dermatitis’)

Multiple sclerosis
Transplant rejections


Acute response:
Associated with B-cell antibody production of IgE and the release of various chemical mediators

Late-Phase response:
Associated with mast cells cytokines and white blood cells; in particular eosinophils and TH2 lymphocytes.

Antibodies (IgG or IgM) bind to foreign cell antigen
Antibody/antigen complex (complement fixation) activates pathways
Cell damage then cell death by Membrane Attack Complex (MAC)
Antibody (IgG) bind to foreign cell antigen
Antibody (IgG) /antigen complexes typically form in circulation/body fluids before being deposited in tissue
Antibody/antigen complex (complement fixation) activates pathways
Cell damage then death by neutrophils + lysosomal enzymes released
T–cells (rather than antibodies) recognize foreign substance
Immune response involving monocytes/macrophages
Target cells destroyed

Discussed in greater depth in:
Allergy Response – Sequence of Events of an Allergy Reaction

Possible role played by IgG/IgG4 is uncertain and debatable at present (e.g. Boluda et al. 1997), as is the scientific value offered by food allergy diagnostic tests for it. For example, IgG/IgG4:
– May contribute to sensitization or conversely confer allergy protection e.g. Kihlström et al. 2005
– Diagnostic tests should be avoided e.g. Wüthrich 2005Stapel et al. 2008

  Possible role played by IgM is uncertain and debatable at present

Type 4 Hypersensitivity is not the same as late-phase Type 1 Hypersensitivity



5 Type Model

Some systems choose to divide Type 2 Hypersensitivity into 2 subcategories, whilst others classify one of these subcategories as being Type 5 Hypersensitivity.

Thus, the 5 type model e.g. in UK, differs from the 4 type system because:
Type 5 Hypersensitivity, seen as being distinct from Type 2 Hypersensitivity, refers to autoimmune disease/receptor mediated conditions
 e.g. Graves’ disease.

7 Category Model
(Sell et al. 1996)
  • Allergic reactions
  • Cytotoxic or cytolytic antibody reactions
  • Delayed hypersensitivity reactions
  • Granulomatous reactions
  • Immune-complex reactions
  • Inactivation/activation antibody reactions
  • T-cell cytotoxic reactions


Johansson et al. 2001


Revised nomenclature for allergy in order to present a more unified definition of hypersensitivity based on allergy, IgE and atopy but regardless of target tissue or organ.


How Hypersensitivity Relates to Dog Allergies


When referring to allergies that affect humans, the term ‘dog allergies’ is quite specific; it implies people who are allergic to dog allergens associated with dog dander or their urine etc. Remember dog related allergies refer to people who are not allergic to dog allergens but rather to other allergens carried on them e.g. dietary or environmental. Furthermore, a person may have concurrent allergies that are both dog specific and dog related.

Thus, Type 1 Hypersensitivity would account for the various symptoms observed in a person sensitized to dog allergens. However, humans can experience allergic reactions/conditions associated with other types of hypersensitivity e.g. Type 2 Hypersensitivity and autoimmune haemolytic, but these are not relevant in the context of people allergic to dogs, dog allergens and the topic of dog allergies.


When referring to allergies that affect dogs (allergies in dogs), the term ‘dog allergies’ is broader in scope; although Type 1 Hypersensitivity is responsible for the vast majority of allergies that affect canines e.g. to food or pollen, there exists a variety of conditions that result from allergic reactions associated with other types of hypersensitivity e.g. systemic lupus/discoid lupus erythematosus (Type 3 Hypersensitivity) or allergic contact dermatitis (Type 4 reaction).

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