Production of interferon-like substances by human bone marrow tissues in vitro.

Three hundred and fifty-six bone marrow tissues obtained from patients of a general hospital were tested for spontaneous production after cultivation in vitro of interferon-like substances (ILS). Seventeen percent of the tissues produced ILS that protected human, but not chick, embryo cell cultures against the cytopathic effects of challenge virus infection. The incidence of ILS did not correlate with leukemia or other neoplastic diseases, or with any non-neoplastic disease.