Isolation of a proliferation inhibitor factor from uterine myomatosis fibroblasts

In this work, we report the isolation of a factor from the culture supernat ant of confluent fibroblasts from human cervix with the diagnosis of uterin e myomatosis. This factor possesses the capacity to inhibit the proliferati on of normal fibroblasts. The proliferation inhibitor factor (PIF) was puri fied from the culture supernatant by precipitation with 80% ammonium sulfat e, and by molecular sieve chromatography. Our results indicate that PIF is a protein of 23 kDa, which is highly sensitive to trypsin treatment, and is thermolabile, since temperatures equal to, or above, 60 degrees C eliminat e the protein activity in 15 to 20 min. Western blot analyses identified no cross reactions of the purified PIF wit h TGF-alpha, TNF alpha, IFN gamma, or IL-1 beta, suggesting that PIF is a n ew protein belonging to the group of factors secreted by fibroblasts able t o inhibit cellular proliferation.