In Vitro Sensitization Assay (IVSA)

Skin Sensitization utilizing 3D Human Tissue Constructs

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Background:

MB Research offers a novel in vitro sensitization screening assay that can be used to identify dermal sensitizers using 3D human dermal tissue equivalent models.

Allergic Contact Dermatitis (ACD), the clinical manifestation of contact sensitization, can be caused by dermal exposure to pharmaceuticals, industrial chemicals, consumer products and cosmetics. This is a serious health concern to consumers and governmental regulatory agencies alike. Contact dermatitis can cause physical, emotional and occupational issues for those affected, with an estimated annual cost of $1 Billion. Substances are routinely tested for sensitization potential in laboratory animal studies, such as the Local Lymph Node Assay.

We have developed an in vitro assay that uses a 3D human differentiated epidermal tissue model that closely parallels human skin, that is composed of human-derived epidermal keratinocytes cultured to form a multilayered, highly differentiated model of the human epidermis. Keratinocytes are the outermost component of skin and provide the first line of defense to chemical exposure. In response to allergens, keratinocytes are capable of producing a wide range of pro-inflammatory cytokines. Evidence suggests that the cytokine IL-18 is an essential component of dermal sensitization.

IL-18 secretion into the tissue culture medium is measured after a 24-hour topical exposure of 12 sensitizers and 5 irritants/non-sensitizers. A Stimulation Index (SI) was calculated relative to the solvent vehicle for each test material; a material with an SI ≥1.6 was considered a positive sensitizer.

In Vitro Sensitization Integrated Testing Strategy

Learn More about the MB Research Integrated Approach using Mechanistic In Vitro Assays

Direct Peptide Reactivity Assay (DPRA)

  • Accepted in vitro assay for dermal sensitization screening by ECVAM
  • Measures molecular reaction of specific peptides to possible sensitizers

Human Cell Line Activation Test (h-CLAT)

  • Examines dendritic cell activation by quantifying changes in the expression of cell surface markers (CD86 and CD54) in the human leukemia cell line THP-1

In Vitro Sensitization ITS

The In Vitro Sensitization Assay (IVSA) is a keratinocyte activation test. IVSA uses an ELISA method to measure IL-18 release from a topically treated reconstructed 3D human keratinocyte tissue model.

The Human Cell Line Activation Test (h-CLAT) is a dendritic cell activation test. The h-CLAT uses flow cytometry to measure CD86 and CD54 expression on treated THP-1 cells in culture.

The Direct Peptide Reactivity Assay (DPRA) is an in chemico method used to predict epidermal protein binding. Binding of epidermal proteins is the molecular initiating event on the AOP. The DPRA uses HPLC to measure the depletion of synthetic peptides in solution following exposure to test chemicals.

Related Links:

TOXNOTE: In Vitro Sensitization Assay using 3D Tissue Model

OECD Test Guideline 442B - LLNA: BrdU ELISA Method