Normal human epidermal keratinocyte-derived neutrophil chemotactic factor

Area of Science:

• Immunology
• Dermatology
• Cell Biology

Background:

• Human epidermal keratinocytes produce cytokines, including a neutrophil chemotactic factor initially mistaken for interleukin-1 (IL-1).
• Recombinant IL-1 lacks chemotactic activity, necessitating identification of the true keratinocyte-derived neutrophil chemoattractant.

Purpose of the Study:

• To characterize the precise nature of the neutrophil chemotactic peptide produced by normal human epidermal keratinocytes.
• To differentiate this factor from IL-1 and confirm its identity.

Main Methods:

• Molecular sieve chromatography to determine molecular size.
• Stability assays (heat, pH, enzymatic treatment) to assess protein characteristics.
• Functional assays using T lymphocytes and in vivo guinea pig models.
• Neutralization studies with anti-IL-1 and anti-NAP-1/IL-8 antibodies.

Main Results:

• Keratinocytes produced an 11,000-dalton chemotactic factor for neutrophils and T lymphocytes.
• The factor was heat-stable and active across a wide pH range (4-11), but sensitive to low pH and trypsin.
• Chemotactic activity was not neutralized by anti-IL-1 but was blocked by anti-NAP-1/IL-8 antibodies.
• Production was stimulated by IL-1 and lipopolysaccharide, but not UV, TNF-α, or IFN-γ.

Conclusions:

• The primary neutrophil chemotactic peptide produced by human epidermal keratinocytes is interleukin-8 (IL-8), not IL-1.
• IL-8 plays a significant role in skin inflammation and immune cell recruitment.
• Keratinocyte-derived IL-8 production is modulated by specific inflammatory stimuli.