Interferon stabilization and enhancement by rare earth salts.

The addition of salts of the rare earth elements (lanthanides) enhances by a factor of two or more the initial activity of human fibroblast, leukocyte and immune interferons as well as mouse L-cell interferon. Furthermore, the salts of the lanthanides (0.01 to 0.002 M) preserve the activity of human fibroblast interferon not only after 4 days of heating at 37 degrees C but also after exposure to severe shearing forces; human leukocyte interferon was stabilized to a lesser degree, albeit significantly.