Two mechanisms of interferon production by leukocytes from immunized animals.

Leukocytes from animals immunized against measles were treated with different doses of interferon and 5-fluorouracil. Under the influence of virus-inducer, two mechanisms of interferon production were realized in the leukocytes: early after immunization (1 day), pre-existing interferon was released; subsequently (4 days) de novo interferon production was started. Interferons induced in cultures of leukocytes from animals at 1 and 4 days after immunization were shown to differ in some physico-chemical properties.