Sensitization test is usually performed to evaluate the potential of biological pharmaceuticals to cause a sensitizing effect or allergenic reaction. Sensitization or hypersensitization is commonly tested by exposing the animal's skin to articles, or taking extracts from the medical devices/implants and injecting them in order to look for adverse reactions.
According to the United State Pharmacopeia, several articles should be considered for sensitization test based on device category and length of exposure.
| Device Category | Body Contact | Contact Duration |
| Surface devices | Skin | a, b, c |
| Mucosal membrane | a, b, c | |
| Breached or compromised surface | a, b, c | |
| External communicating devices | Blood path, indirect | a, b, c |
| Tissue, bone, or dentin communicating | a, b, c | |
| Circulating blood | a, b, c | |
| Implant devices | Tissue or bone | a, b, c |
| Blood | a, b, c |
a: limited (less than 24 hours)
b: prolonged (24 hours to 30 days)
c: permanent (more than 30 days)
* reference see The United States Pharmacopeia (USP 35-NF 30)
Methodologies for sensitization test
- Magnusson & Kligman Maximization (Guinea pig)
- Standard Buehler (Guinea pig)
- Draize Test (Guinea pig)
- Open Epicutaneous (Guinea pig)
- Freund's Complete Adjuvant (Guinea pig)
- Optimization (Guinea pig)
- Split Adjuvant (Guinea pig)
- Local Lymph Noda Assay (Mouse)
- Mouse Ear Swelling (Mouse)
- Vitamin A Enhancement (Mouse)
Among all the sensitization test procedures, the Magnusson & Kligman Guinea Pig Maximization Test (GPMT) and Standard Buehler Tests (SBT) are the most commonly used methods. Besides, other methods also can be performed to assess the potential of sensitization or hypersensitization. Each test mentioned above should be validated by using positive controls during performing.
Magnusson & Kligman Guinea Pig Maximization Test (GPMT)
GPMT is an in vivo sensitization testing assay to determine the sensitizing potential of the articles. This method was first proposed by B. Magnusson and Albert Kligman in 1969[1] and was preferred in the OECD Guidelines for the Testing of Chemicals guideline No. 406 in 1992.[2] The healthy guinea pigs are injected intradermally with test article, along with an adjuvant to enhance the immune reaction of the test animals. The guinea pigs are exposed to the test articles for a period of time, and their allergic reaction, if any, measured. The test is considered positive when 10% of test animals must show allergenic reaction. It is necessary to use 20 test animals for ensuring sufficient results.
Standard Buehler Tests (SBT)
SBT is another in vivo test to screen for articles with potential sensitization. It was first proposed by Edwin Vernon Buehler in 1965[2]. This method is a non-adjuvant test compare to GPMT. Guinea pigs are initially exposed to a high dose of the test articles in SBT. After the induction time of 10-14 days, the test animals are given a challenge dose, which is the highest nonirritant dose.[3]
Scientists from Creative Proteomics are experienced in sensitization or hypersensitization analysis. So Creative Proteomics is ready to provide professional assistance for sensitizing reaction in order to determine the safety of biopharmaceuticals.
[1] The identification of contact allergens by animal assay. The guinea pig maximisation test. Magnusson B, J Invest Dermatol., 1969, 52(3).
[2] Delayed contact hypersensitivity in the guinea pig. Buehler EV., Arch Dermatol., 1965, 91.
[3] http://www.oecd-ilibrary.org/environment/test-no-406-skin-sensitisation_9789264070660-en
