Direct Peptide Reactivity Assay

Commonly used acronym: DPRA

Scope of the method

The Method relates to
  • Human health
The Method is situated in
  • Basic Research
  • Regulatory use - Routine production
Type of method
  • In chemico


Method keywords
  • toxicology
  • OECD
  • AOP
  • Molecular initiating event
Scientific area keywords
  • Skin Sensitisation
  • in vitro
  • Toxicology
  • OECD
  • AOP
  • molecular initiating event
Method description

The DPRA is an in chemico method which quantifies the remaining concentration of cysteine- or lysine-containing peptide following 24 hours incubation with the test chemical at 25 +/-2,5ºC. The synthetic peptides contain phenylalanine to aid in the detection. Relative peptide concentration is measured by highperformance liquid chromatography (HPLC) with gradient elution and UV detection at 220 nm. Cysteineand lysine peptide percent depletion values are then calculated and used in a prediction model (see paragraph 29) which allows assigning the test chemical to one of four reactivity classes used to support the discrimination between sensitisers and non-sensitisers.

Lab equipment


Method status
  • History of use
  • Internally validated
  • Validated by an external party (e.g. OECD, EURL ECVAM,…)

Pros, cons & Future potential

  • Validated methodology (EURL ECVAM) ;
  • AOP based ;
  • High throughput ;
  • Low cost ;
  • In chemico.

The test method described in this Test Guideline is an in chemico method that does not encompass a metabolic system.

Future & Other applications

The methodology behind AOP and MIE can be applied to other toxicological endpoints.

References, associated documents and other information


OECD, TG 442C, OECD GUIDELINE FOR THE TESTING OF CHEMICALS, In Chemico Skin Sensitisation: Direct Peptide Reactivity Assay (DPRA)

Contact person

Bart Desmedt


Chemical and physical health risks
Medicines and health products
Brussels Region