Medical Analysis

Milk Allergy Pathophysiology, Immune Mechanisms, and Diagnostic Principles By Dr. Dipak Ladda M.D.

Introduction to Milk Allergy Pathophysiology, Immune Mechanisms, and Diagnostic Principles

If you have an allergy, your immune system mistakenly identifies the allergen as a threat or invader [3, 9]. It produces antibodies called immunoglobulin E (IgE) to fight off the threat [3, 9]. These antibodies trigger the release of chemicals that cause an allergic reaction [3, 9]. These reactions occur immediately, within a few minutes to a few hours of antigen contact [3, 9]. Allergy tests measure your body’s response to specific allergy triggers or allergens [3, 5].

Understanding milk allergy involves looking at how the body reacts to specific dairy proteins [2, 3]. Someone who is allergic to milk and milk products may develop symptoms after ingestion as follows, including abdominal bloating and pain, loose stool, nausea, and flatulence [2, 3].

Milk allergies are classified into different categories based on their underlying immunological pathways:

Further categorization aligns with the Gell and Coombs hypersensitivity classification system regarding milk allergy reactions:

Common Milk Materials, Clinical Manifestations, and Diagnostic Frameworks

Different milk types contain specific proteins capable of triggering allergic reactions across various species:

Clinical manifestations present in distinct early and late phases [2, 3]. Early clinical manifestations include hives or urticaria, vomiting, itching or tingling of the mouth or lips, swelling of the lips, tongue, or throat (angioedema), coughing, wheezing, stridor, and anaphylaxis which presents as a rapid onset, severe reaction [2, 3]. Late clinical manifestations include diarrhea which may be bloody or mucous, abdominal cramps or colic, eczema flare-ups, persistent nasal congestion, runny nose, poor growth or failure to thrive in infants, and delayed vomiting and gastrointestinal symptoms [2, 3].

The diagnosis of milk allergy involves a comprehensive evaluation workflow [3, 5]:

• Take a thorough history of symptoms related to milk ingestion [3, 5].

• Conduct a physical examination focusing on skin and gastrointestinal manifestations [3, 5].

• Perform skin prick tests with milk protein allergens [3, 5].

• Order serum specific IgE blood tests against milk proteins such as casein and whey [3, 5].

• Use atopy patch test for delayed non-IgE-mediated reactions [3, 6].

• Implement an elimination diet removing milk protein for 1 to 2 weeks under supervision [3, 5].

• Conduct supervised oral food challenge to confirm diagnosis if needed [3, 5].

• Interpret results holistically combining history, tests, and clinical response [3, 5].

The primary specific allergens evaluated include milk, alpha-lactalbumin, beta-lactoglobulin, casein, and bovine serum albumin [3, 5].

The core clinical indications for testing include diagnosing milk and dairy product allergies, useful in evaluating lactose intolerance versus milk protein allergy, helping in managing dietary restrictions related to milk allergies and formulating dietary avoidance strategies for milk and dairy products, and guiding in potential desensitization for milk-related allergies [3, 5].

Laboratory Sample Preparation, Total IgE Levels, and Specific Assays

Sample preparation requires careful handling to ensure accurate assay results [5, 9]. Specimen type must be blood, specifically serum or plasma, with a collection volume of 3 mL [5, 9]. Causes for specimen rejection include gross hemolysis, lipemia, and icterus [5, 9]. Storage conditions allow room temperature maintenance for 24 hours or refrigeration at 2 degrees Celsius to 8 degrees Celsius for 14 days [5, 9].

Total IgE level measures the overall quantity of immunoglobulin E in the blood, not the amount of a specific type [3, 9]. IgE levels are increased in allergy and help in screening and detecting allergies, while antigen-specific IgE can help to identify the responsible allergen [3, 5]. Testing methods include turbidometry and electrochemiluminescence immunoassay, with a normal reference range of 0 to 200 IU/mL [3, 5].

Specific IgE testing uses advanced methods such as chemiluminescence, fluoroenzymeimmunoassay, ELISA, and immunoblotting [3, 5].

Interpretation guidelines state that results for allergen mixes are qualitative values, and 0.10 kUA/L is recommended as a cut-off value [3, 5]. Values at or above 0.10 kUA/L indicate specific IgE antibodies to one or more of the allergens, whereas a value below 0.10 kUA/L indicates undetectable levels or very low levels of allergen-specific IgE antibodies [3, 5]. The cut-off value may vary from kit to kit, and the cut-off for ELISA is 0.35 IU/mL [3, 5].

A general interpretation of IgE antibody levels in relation to clinical symptoms must also be correlated with the age of the patient, type, degree and load of sensitizing allergens, previous symptoms, and other triggering factors [3, 5]:

Advantages, Clinical Significance, Management Strategies, and Limitations

The multiplex assay offers distinct advantages owing to its simultaneous analysis of immunoglobulin E against multiple allergens in a single blood sample, which helps in screening and detecting allergic triggers associated with milk and milk products [3, 5].

Clinical significance emphasizes that milk allergy can cause mild to severe allergic reactions, including hives, swelling, vomiting, abdominal pain, and anaphylaxis [2, 3]. It is a leading cause of food allergy in children and can be life-threatening if not recognized and managed [2, 3]. Chronic exposure may lead to persistent digestive issues, poor growth, or failure to thrive in infants [2, 3]. Early identification is crucial to prevent severe reactions and improve quality of life [3, 5]. Distinguishing milk allergy from intolerance is essential for correct management and dietary advice [3, 5].

Patient management and prevention strategies involve strict avoidance of milk and milk-containing products, always reading food labels to check for milk protein derivatives, breastfeeding exclusively when possible to reduce allergy risk, using hypoallergenic or extensively hydrolyzed formula under medical guidance if breastfeeding is not possible, having emergency medications like epinephrine available for severe reactions, gradually reintroducing milk proteins only under medical supervision after tolerance is established, and consulting healthcare providers regularly for monitoring and management updates [3, 5, 9].

Home remedies suggested for adjunctive comfort include strict avoidance of milk and milk products, drinking fennel and cumin seed water twice daily, taking ginger slices with rock salt before meals, consuming fresh Aegle marmelos or belgiri juice once daily, eating steamed apples for their anti-inflammatory effects, boiling fenugreek seeds with jaggery and taking on an empty stomach, including turmeric, fennel, and cumin in the diet, using dairy-free milk alternatives like almond or coconut milk, and breastfeeding infants where possible to reduce allergy risk [3, 5].

Routine permissible over-the-counter medicines to be kept at home after consulting a doctor include specific therapeutic classes:

Limitations of testing protocols note that in multiplex assays, IgG antibodies may interfere and give false positive results [3, 5].

For Non-Medicos

Understanding Milk Allergies

A milk allergy happens when your immune system mistakenly treats milk proteins as harmful invaders, releasing chemicals that cause immediate allergic reactions [3, 9].

Symptoms to Watch For

Reactions can range from mild issues like hives, stomach pain, bloating, gas, and nausea to severe, life-threatening emergencies like breathing trouble and anaphylaxis [2, 3].

Testing and Diagnosis

Doctors diagnose milk allergies through physical exams, skin prick tests, elimination diets, and blood tests that measure specific IgE antibodies against dairy proteins [3, 5].

Management and Safety Tips

Managing a milk allergy involves strictly avoiding dairy, reading food labels carefully, keeping emergency epinephrine ready, and consulting healthcare providers for personalized guidance [3, 5, 9].

References:

1. Bernstein DI, Malo JL, Bernstein IL. Asthma in the workplace. 3rd ed. Boca Raton: CRC Press; 2006.

2. Chan-Yeung M, Malo JL. Occupational asthma. N Engl J Med. 1995;333(2):107-112.

3. Baur X, Degens PO, Sander I. The burden of occupational asthma and allergy: a review. Curr Opin Allergy Clin Immunol. 2005;5(2):165-170.

4. Tarlo SM, Lemiere C. Occupational asthma. N Engl J Med. 2014;370(7):640-649.

5. Nicholson PJ, Cullinan P, Taylor AJ, et al. Evidence based guidelines for the prevention, identification, management and investigation of occupational asthma. Occup Environ Med. 2005;62(5):290-299.

6. Johansen JD, Frosch PJ, Lepoittevin JP. Contact dermatitis. 5th ed. Berlin: Springer; 2011.

7. Alanko K, Keskinen H, Tuomasjukka S, Staff S. Occupational skin diseases and respiratory diseases among workers in Finland. Contact Dermatitis. 2004;50(5):314-318.

8. Jeebhay MF, Quirce S. Occupational asthma in the developing world. Curr Opin Allergy Clin Immunol. 2007;7(2):134-142.

9. Bernstein IL, Chan-Yeung M, Malo JL, Bernstein DI. Definition, epidemiology, causes, and pathophysiology of occupational asthma. Chest. 2003;123(3):682-692.

10. Ross JA, Curtis L. Occupational contact dermatitis: a review of the literature. Dermatitis. 2010;21(3):123-138.

11. Malo JL, Chan-Yeung M. Agents causing occupational asthma. Eur Respir J. 2009;34(4):985-1002.

12. Crowther J, Armstrong S, et al. Health surveillance and prevention measures for occupational lung and skin diseases. Occup Med (Lond). 2012;62(4):250-258.

FAQ’s:

• What is a milk allergy?
  Immune system mistakenly identifies milk proteins as harmful invaders, triggering an allergic reaction.

• What are common allergy symptoms?
  They include hives, vomiting, mouth itching, swelling, wheezing, and potentially life-threatening anaphylaxis.

• What causes delayed milk reactions?
  Delayed non-IgE-mediated reactions involve T-cell mechanisms causing issues like enterocolitis and proctocolitis.

• Which dairy animals cause allergies?
  Cow, goat, sheep, buffalo, and camel milk all contain casein and whey proteins.

• How are milk allergies diagnosed?
  Through medical history, physical exams, skin prick tests, and specific IgE blood tests.

• What is total IgE testing?
  It measures overall immunoglobulin E levels in blood to help screen and detect allergies.

• What is the ELISA cut-off?
  The cut-off threshold for ELISA testing is 0.35 IU/mL to confirm specific antibodies.

• What are multiplex assay advantages?
  It allows simultaneous analysis of immunoglobulin E against multiple allergens from a single blood sample.

• How do you prevent reactions?
  Strictly avoid milk products, read food labels carefully, and keep emergency epinephrine available.

What is the main limitation?
IgG antibodies may interfere in multiplex assays and cause false positive results.

Related  Tests

• Skin Prick Test (SPT) for Milk Proteins