Nickel-keratinocyte interaction: a possible role in sensitization.

Area of Science:

• Dermatology
• Toxicology
• Immunology

Background:

• Nickel (Ni2+) is a common environmental allergen.
• Keratinocytes are the primary cells in the epidermis.
• Understanding nickel's effects on skin cells is crucial for allergy research.

Purpose of the Study:

• To investigate the effects of nickel ions (Ni2+) on normal human keratinocytes and keratinocyte-derived cell lines.
• To determine the dose- and time-dependent toxicity of nickel on skin cells.
• To assess nickel-induced inflammatory responses and potential for sensitization.

Main Methods:

• Exposure of keratinocytes (NCTC 2544, A 431) and normal human keratinocytes to varying nickel concentrations (0.023-46.6 µg/ml) for different durations (1-5 days).
• Assessment of cell growth inhibition and viability.
• Measurement of interleukin-1 (IL-1) release from keratinocytes.
• Evaluation of lipoxygenase activation in leukocytes following short-term nickel exposure.

Main Results:

• Nickel ions (Ni2+) demonstrated a dose- and time-dependent inhibition of keratinocyte growth and viability.
• Approximately 50% cell survival was observed at 2.3 µg Ni2+/ml after 5 days.
• Increased interleukin-1 (IL-1) release was detected in keratinocytes cultured with 2.3-11.5 µg Ni2+/ml for 24 hours.
• Short incubation periods (30 min) with nickel activated lipoxygenase in leukocytes without affecting cell viability.

Conclusions:

• Percutaneous penetration of nickel (Ni2+) can cause damage to keratinocytes.
• Nickel exposure can lead to the release of inflammatory mediators like IL-1.
• These effects suggest that nickel can initiate skin sensitization and allergic contact dermatitis.