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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in chemico
Type of information:
experimental study
Adequacy of study:
key study
Study period:
01.05.2018 - 04.05.2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Report date:
2018

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 442C (In Chemico Skin Sensitisation: Direct Peptide Reactivity Assay (DPRA))
GLP compliance:
yes (incl. QA statement)
Type of study:
direct peptide reactivity assay (DPRA)
Justification for non-LLNA method:
In 2012 the OECD published an Adverse Outcome Pathway (AOP), which describes the biological mechanisms of skin sensitisation initiated by the covalent
binding of substances to skin proteins.The key events of this skin sensitisation pathway are:
1. covalent binding of the electrophilic substance to skin proteins
2. release of pro-inflammatory cytokines and induction of cyto-protective pathways in kerationocytes
3. activation and maturation of dendritic cells and their migration to the local lymph nodes
4. presentation of the chemical allergen by the dendritic cells to naive T-cells, which leads to their differentiation and proliferation into allergen-specific memory
T-Cells.
DPRA addresses the first key event of the AOP

Test material

Reference
Name:
Unnamed
Type:
Constituent

In chemico test system

Details on the study design:
The study was performed according to the OECD Guideline 442C and the Protocol N° 154 from ECVAM DB ALM.
The principle is based on chemical reactivity of the test item with proteins. The interaction between the molecule and lysine or cysteine rich peptides is detected with a high performance liquid chromatography (HPLC). The remaining concentration of peptides is measured after 24 hours of incubation with the test item at 25°C. It is measured with the UV detector of the HPLC system, after gradient elution,at 220 nm. The depletion rates of lysine and cysteine peptides are then used to distinguish the skin sensitizer and non-sensitizer.

The following table allows a determination of reactivity: the 6.38% threshold is used in order to differentiate between non-sensitizers and sensitizers.

Mean of cysteine and lysine% depletion Reactivity Class DPRA Prediction
0.00 % ≤ mean% depletion ≤ 6.38 % No or minimal reactivity Negative
6.38 % < mean% depletion ≤ 22.62 % Low reactivity Positive
22.62 % < mean% depletion ≤ 42.47 % Moderate reactivity Positive
42.47 % < mean% depletion ≤ 100 % High reactivity Positive

Results and discussion

In vitro / in chemico

Resultsopen allclose all
Parameter:
other: Mean Depletion in Lysine Peptide %
Value:
0.39
Parameter:
other: Mean Depletion in Cysteine Peptide %
Value:
4.4
Key result
Parameter:
other: Calculated mean percentage of depletion of Lysine and Cysteine
Value:
2.4

Any other information on results incl. tables

   Depletion in Lysine Peptide % Depletion in Cysteine Peptide % 
 Repetition 1  4.04
 Repetition 2  0  4.44
 Repetition 3  1.18  4.72
 MEAN  0.39  4.40

Applicant's summary and conclusion

Interpretation of results:
other: DPRA is considered scientifically valid to be used as part of an integrated approach.
Conclusions:
The sensitivity of the test item is determined by calculating the mean percentage of depletion of Lysine and Cysteine.
The test item Oleic acid. compound with dicyclohexylamine shows mean depletion of 0.39 % for Lysine and 4.40 % for Cysteine, i.e. an overall average of 2.40 % reflecting no or minimal reactivity and therefore a negative prediction of DPRA.