Production of both interleukin-lα and ß by newborn mouse calvarial cultures

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Abstract
The conditioned medium (CM) from 4–6 day newborn mouse calvarial cultures was found to contain thymocyte comitogen proliferation activity. This activity was blocked by an antiserum to murine interleukin-1α (IL-1α) but not by an antiserum to murine interleukin-1ß. The release of thymocyte comitogen proliferation activity from the cultures did not appear dependent on endotoxin and was not associated with detectable interleukin-2 activity in the CM. Activity in the CM eluted from a gel filtration column with a peak Mr of 16–18 kD (the Mr of mature murine IL-1α and ß is 17 kD). Western immunoblots of 100-fold concentrated CM demonstrated only a single 33 kD band with an antiserum to murine IL-1ß and no bands with an antiserum to murine IL-1α. However, this assay was relatively insensitive (limit of detection 1–10 ng compared with 1–10 pg for the thymocyte comitogen proliferation assay). Immunoprecipitation of [35S]methionine-labeled CM with three different anti-IL-1α antisera, a more sensitive assay, demonstrated 15–17 kD bands in all cases. These results demonstrate that 4–6 day newborn mouse calvarial cultures spontaneously release 17 kD IL-1α and 33 kD IL-1ß into their conditioned medium. It appears that although 17 kD IL-1α is the major bioactive form in the CM, 33 kD IL-1ß is present in greater amounts. These results also suggest that local production of IL-1 can regulate bone cell function and may play a role in bone growth and remodeling
Funding Information
  • Medical Research Service (AR-31263, AR-38933, AR-32343)
  • U.S. Public Health, Service