Immunology: Allergic rhinitis Flashcards
Describe the pathophysiology of allergic rhinitis [1]
Type-1 hypersensitivity IgE mediated reaction causing cause an allergic inflammatory response in the nasal mucosa.
Describe the presentation of allergic rhinitis [+]
Runny, blocked and itchy nose
- On nasal examination, the mucosa appears pale or violaceous with clear, thin secretions.
- Nasal polyps may be present in severe or chronic cases
Sneezing
Itchy, red and swollen eyes
- Allergic shiners (dark circles under the eyes) and a horizontal crease across the lower half of the bridge of the nose (allergic salute) due to repeated upward rubbing of the nose
Cognitive Impairment:
- Patients may report concentration difficulties, memory problems or fatigue related to poor sleep quality due to nocturnal symptoms.
May be accompanied by systemic symptoms such as malaise and lethargy particularly during peak pollen seasons for those with seasonal allergic rhinitis.
In children, persistent allergic rhinitis may be associated with otitis media with effusion (glue ear).
What are the classifications of allergic rhinitis? [3]
seasonal: symptoms occur around the same time every year. Seasonal rhinitis which occurs secondary to pollens is known as hay fever
perennial: symptoms occur throughout the year
occupational: symptoms follow exposure to particular allergens within the work place
What is the difference between non-allergic rhinitis (NAR) and allergic rhinitis [1]
How do they present differently? [2]
NAR often presents similarly to allergic rhinitis, but lacks the immunoglobulin E (IgE) mediated response seen in the latter.
- Patients with NAR typically experience chronic nasal symptoms including rhinorrhoea, congestion and sneezing.
- However, unlike allergic rhinitis, these symptoms are NOT seasonal and do NOT respond well to antihistamines.
How do you differentiate between allergic rhinitis and infective sinusitis? [2]
Ppatients with sinusitis often present with additional symptoms such as facial pain or pressure and fever which are not seen in allergic rhinitis.
The presence of purulent nasal discharge is another key differentiating factor.
How do you manage allergic rhinitis? [4]
allergen avoidance
if the person has mild-to-moderate intermittent, or mild persistent symptoms:
* oral or intranasal antihistamines: Non-sedating antihistamines include cetirizine, loratadine and fexofenadine &
Sedating antihistamines include chlorphenamine (Piriton) and promethazine
if the person has moderate-to-severe persistent symptoms, or initial drug treatment is ineffective:
* intranasal corticosteroids such as such as fluticasone and mometasone
a short course of oral corticosteroids are occasionally needed to cover important life events
there may be a role for short courses of topical nasal decongestants (e.g. oxymetazoline).
- They should not be used for prolonged periods as increasing doses are required to achieve the same effect (tachyphylaxis) and rebound hypertrophy of the nasal mucosa (rhinitis medicamentosa) may occur upon withdrawal
Describe the correct way to do nasal spray technique for allergic rhinitis? [4]
The aim when administering a nasal spray is to get a good coating throughout the nasal passage.
Hold the spray in the left hand when spraying into the right nostril and vice versa.
Aim to spray slightly outward, away from the nasal septum.
Do NOT sniff at the same time as spraying, as this sends the mist straight to the back of the throat.
The patient should not taste the spray at the back of the throat. If they do, that means it has gone too far.
[] deficiency is the most common complement deficiency.
C2 deficiency is the most common complement deficiency.
Describe what is meant by C1 Esterase Inhibitor Deficiency (Hereditary Angioedema) [3]
Bradykinin is part of the inflammatory response
- It is responsible for promoting blood vessel dilatation and increased vascular permeability, leading to angioedema
- Part of the action of C1 esterase is to inhibit bradykinin.
- An absence of C1 esterase causes intermittent angioedema in response to minor triggers, such as viral infections or stress, or without any clear trigger at all.
Angioedema often affects the lips or face but can occur anywhere on the body, including the respiratory and gastrointestinal tract.
- The swelling can last several few days before self resolving. Angioedema can occur in the larynx and compromise the patients airway.
TOM TIP: A key test for hereditary angioedema (C1 esterase inhibitor deficiency) is to check the levels of []
[] levels will be high/low in the condition.
The exam question describe a patient with episodes of unexplained lip swelling and ask what test to perform. The answer is [] levels.
TOM TIP: A key test for hereditary angioedema (C1 esterase inhibitor deficiency) is to check the levels of C4 (compliment 4).
C4 levels will be low in the condition.
The exam question describe a patient with episodes of unexplained lip swelling and ask what test to perform. The answer is C4 levels.
Describe the symptoms of hereditary angioedema
attacks may be proceeded by painful macular rash
painless, non-pruritic swelling of subcutaneous/submucosal tissues
- may affect upper airways, skin or abdominal organs (can occasionally present as abdominal pain due to visceral oedema)
urticaria is NOT usually a feature
How do you treat HAE? [2]
IV C1-inhibitor concentrate
fresh frozen plasma (FFP) if this is not available
NB: HAE does not respond to adrenaline, antihistamines, or glucocorticoids
Describe what is meany by Severe combined immunodeficiency (SCID) [1]
What is the pathophysiology [3]
Severe combined immunodeficiency (SCID) is the most severe condition causing immunodeficiency. Children with SCID have almost no immunity to infections.
- It is a syndrome caused by a number of different genetic disorders that result in absent or dysfunctioning T and B cells
- More than 50% of cases are caused by a mutations in the common gamma chain on the X chromosome that codes for interleukin receptors on T and B cells. This has X-linked recessive inheritance.
There are many other gene mutations that can lead to SCID including:
* JAC3 gene mutations
* Mutations leading to adenosine deaminase deficiency
How does SCID present in the first few months of life? [5]
SCID will present in the first few months of life with:
* Persistent severe diarrhoea
* Failure to thrive
* Opportunistic infections that are more frequent or severe than in healthy children, for example severe and later fatal chickenpox, Pneumocystis jiroveci pneumonia and cytomegalovirus
* Unwell after live vaccinations such as the BCG, MMR and nasal flu vaccine
* Omenn syndrome
Describe what is meant by Omenn syndrome [2]
Omenn syndrome is a rare cause of SCID. It is the result of a mutation in the recombination-activating gene (RAG 1 or RAG 2) that codes for important proteins in T and B cells. It has autosomal recessive inheritance.
- The syndrome is caused by abnormally functioning and deregulated T cells that attack the tissues in the fetus or neonate.
What are the presenting features of Omenn syndrome? [5]
A red, scaly, dry rash (erythroderma)
Hair loss (alopecia)
Diarrhoea
Failure to thrive
Lymphadenopathy
Hepatosplenomegaly
Describe what is meant by common variable immunodeficiency [including pathophysiology, presentations, treatment] and x-linked agammaglobulinaemia
Common Variable Immunodeficiency
* Common variable immunodeficiency is caused by a genetic mutation in the genes coding for components of B cells. The result is deficiency in IgG and IgA, with or without a deficiency in IgM.
* This leads to recurrent respiratory tract infections, typically leading to chronic lung disease over time.
* Patients are unable to develop immunity to infections or vaccinations.
* They are also prone to immune disorders such as rheumatoid arthritis, and cancers such as non-Hodgkins lymphoma.
* Management is with regular immunoglobulin infusions and treating infections and complications as they occur.
X-linked Agammaglobulinaemia
- X-linked agammaglobulinaemia is also known as Bruton’s agammaglobulinaemia. This is an X-linked recessive condition.
- It results in abnormal B cell development and deficiency in ALL classes of immunoglobulins.
- It causes similar issues to common variable immunodeficiency.
Describe what is meant by DiGeorge syndrome, Purine Nucleoside Phosphorylase Deficiency, Wiskott-Aldrich Syndrome and Ataxic Telangiectasia
DiGeorge Syndrome- Features of DiGeorge syndrome can be remembered with the CATCH-22 mnemonic:
C – Congenital heart disease
A – Abnormal facies (characteristic facial appearance)
T – Thymus gland incompletely developed
C – Cleft palate
H – Hypoparathyroidism and resulting Hypocalcaemia
Purine Nucleoside Phosphorylase Deficiency
- PNPase is an enzyme that helps breakdown purines. Without this enzyme, a metabolite called dGTP builds up
- This metabolite is exclusively toxic to T cells.
- Increased levels of dGTP causes low levels of T-lymphocytes. There are normal levels of B cells and immunoglobulin
Wiskott-Aldrich Syndrome
Mutation on the WAS gene. It causes abnormal functioning of T cells. Other features include:
* Thrombocytopenia
* Immunodeficiency
* Neutropenia
* Eczema
* Recurrent infections
* Chronic bloody diarrhoea
Ataxic Telangiectasia:
* Low numbers of T-cells and immunoglobulins, causing immunodeficiency and recurrent infections.
* Ataxia: problems with coordination due to cerebellar impairment
* Telangiectasia, particularly in the sclera and damaged areas of skin
* Predisposition to cancers, particularly haematological cancers
* Slow growth and delayed puberty
* Accelerated ageing
* Liver failure
