Abstract
Interleukin (IL)-3-like bioactivity has been found in culture supernatants from human and murine keratinocytes. However, there is controversy as to the presence of IL-3 mRNA in human keratinocytes. Using highly sensitive reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay techniques, we examined human keratinocytes from four different donors (neonatal foreskins) and were unable to detect IL-3 mRNA or IL-3 protein. Despite successful amplification of DNA from an IL-3 cDNA, no product could be obtained by amplification of keratinocyte RNA treated with reverse transcription-polymerase chain reaction. Analysis of concentrated (up to 50-fold) supernatants failed to detect IL-3 protein by enzyme-linked immunosorbent assay. Because ultraviolet radiation up-regulates many cytokines, we irradiated human keratinocytes with 300 J/m2 ultraviolet B and collected supernatants 24 h post-irradiation. Supernatants concentrated 50-fold were also negative for IL-3 protein by enzyme-linked immunosorbent assay. When assayed on the IL-3-responsive M-07e cell line, unirradiated supernatants stimulated M-07e proliferation 22-fold over background levels. Irradiated supernatants stimulated M-07e proliferation 128-fold. Neither the unirradiated nor the irradiated supernatant activity could be neutralized with antibody to human IL-3. However, incubation of irradiated supernatants with antibody to granulocyte macrophage-colony-stimulating factor (GM-CSF) reduced the M-07e proliferation by 90%. Antibodies against GM-CSF and IL-6 completely abrogated proliferation. Reverse transcription-polymerase chain reaction confirmed a concomitant elevation of IL-6 (2.6- to 5.6-fold) and of GM-CSF mRNA (2.7- to 4.3-fold) at 6 and 24 h after ultraviolet B irradiation in keratinocytes, but no IL-3 amplification products could be detected. IL-3 mRNA was also not detected in adult keratinocytes. Even after stimulation by IL-1 alpha, tumor necrosis factor-alpha, or phobol myristate acetate, IL-3 mRNA was not detected in either neonatal or adult human keratinocytes. We have been unable to detect IL-3 mRNA or IL-3 protein in human keratinocytes. The IL-3-like activity in human keratinocytes is mainly due to GM-CSF, with a small contribution from IL-6.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
