OECD 442E h-CLAT Testing



The OECD 442E: h-CLAT Test investigates key event 3 of the skin sensitisation adverse outcome pathway—dendritic cell activation, crucial for both innate and adaptive immune responses. Utilising the monocytic THP-1 cell line, the ability of a test substance to increase expression of CD54 & CD86 cell surface markers is assessed by flow cytometry. Upregulation of these cell markers, often seen in autoimmune diseases, is associated with dendritic cell activation, which includes interactions with Langerhans cells and plasmacytoid dendritic cells. This activation leads to the stimulation of an immune response required for sensitisation of the skin to the test substance.

h-CLAT protocols have been validated, and laboratory proficiency under OECD 442E has been established at Gentronix. Services are available in both GLP and non-GLP formats, supporting research into antigen-presenting cells, natural killer cells, and other cell types involved in the immune system. The test aids in understanding cross-presentation in lymphoid tissues and bone marrow, enhancing knowledge of the adaptive immune response and the role of cells like Tregs in immune regulation.

OECD guidelineOECD 442E
Adverse Outcome Pathway Key EventNumber 3 – activation of dendritic cells
What it measuresIncrease in expression of cell surface markers (CD86 and CD54) measured by flow cytometry
What is the relevance of that?Expression of CD54 & CD86 is linked to the activation of dendritic cells, which is a precursor event for the stimulation of T-cell proliferation, leading to skin allergenicity
Test Systemhuman monocytic leukaemia cell line THP-1
Test Item Requirements 1 g

h-CLAT OECD 442E Proficiency Data

Gentronix values consistent with OECD reference rangeGentronix study calls consistent with OECD reference
Test chemicalIn vivo classificationCV75CD86CD54CD86 CallCD54 Callh-CLAT classificationClassification correct
2,4-DinitrochlorobenzeneSensitiser (extreme)PositivePositiveSensitiser
4-PhenylenediamineSensitiser (strong)PositiveNegativeSensitiser
Nickel sulfateSensitiser (moderate)PositivePositiveSensitiser
2-MercaptbenzothiazoleSensitiser (moderate)NegativePositiveSensitiser
R(+)-LimoneneSensitiser (weak) Negative PositiveSensitiser
Imidazolidinyl ureaSensitiser (weak) Positive PositiveSensitiser
IsopropanolNon-sensitiser Negative NegativeNon-sensitiser
GlycerolNon-sensitiser Negative NegativeNon-sensitiser
Lactic acidNon-sensitiser Negative NegativeNon-sensitiser
4-Aminobenzoic acidNon-sensitiser Negative NegativeNon-sensitiser

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