With the development of reliable in chemico/in vitro assays, manufacturers and formulators are now able to determine whether or not a substance is a skin sensitizing agent without the need for animal testing. Each of the available assays recapitulates some element of the adverse outcome pathway (AOP) associated with a skin sensitization response in humans. Using an integrated testing strategy that incorporates these approaches for identifying skin sensitization hazard risk (as outlined by the Globally Harmonized System of Classification and Labelling of Chemicals) ensures regulatory compliance as well as consumer safety and satisfaction.

Overview of Human Cell Line Activation Method

In humans, multiple exposures to a skin sensitizer may cause activation of the immune system’s dendritic cells. Activation of these cells in the body is evidenced by changes in surface molecules on the dendritic cells. This event is regarded as the third key event in the skin sensitization adverse outcome pathway and is modeled in the h-CLAT in vitro assay. The h-CLAT measures the expression of specific cell surface makers associated with maturation of dendritic cells (i.e., CD86, CD54) in a human monocytic leukemia cell line (THP-1 cells).

Cells are exposed to the test material for 24 hours before cell surface maker expression is evaluated by staining the markers with fluorochrome-tagged antibodies and quantifying positively-stained populations using flow cytometry. Sensitizers are identified by comparing the relative fluorescence intensity of cell populations exposed to the materials versus cells that were exposed to solvent/vehicle controls.

The h-CLAT must be used in conjunction with additional assays to confidently determine a substance’s safety and skin sensitization potential as some materials (such as metabolically-driven sensitizers) may not be suitable for this assay.

Our Capabilities

CPT uses state-of-the-art testing laboratories, including labs that specialize in Analytical, Clinical, and In-Vitro Toxicology testing. All of our testing facilities are at your disposal for evaluating skin sensitization potential.

In our highly experienced and specialized departments, we test a wide range of cosmetic and personal care products. Our experts offer our clients guidance on the best testing strategies to ensure consumer safety and satisfaction as well as regulatory compliance.

Our Departments

In response to the multifaceted nature of cosmetic and personal care product safety testing, we are proud to provide our clients with support that can be tailored to meet your individual and evolving needs. The product(s) under evaluation will determine which department(s) ultimately assist your product testing endeavors. Our clients typically take advantage of the diverse expertise that CPT offers by calling upon our specialists from a variety of departments, including:

  • Clinical – CPT performs safety and efficacy tests to support pre-market testing, performance validation, and claims such as ‘dermatologist-tested’ and ‘ophthalmologist-tested.’
  • In-Vitro Safety – We offer alternative testing methods to meet the needs of the cosmetics industry when it comes to non-animal or animal-tree toxicology evaluations.
  • Microbiology – From preservative efficacy to stability testing, CPT has a variety of testing approaches at your disposal for microbial contamination potential and preservative testing evaluations for cosmetics.
  • Photobiology – CPT is the industry leader in photobiology testing, from supporting SPF and Water-Resistant claims to PhotoAllergy and Phototoxicity assays.
  • Analytical – Our analytical team provides support at all levels of product evaluation, from raw materials to stability shelf-life testing to “free-of” and low-level detection claims. Our experts will ensure that all regulatory requirements are met.

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