Modulation by adherent cells and irradiation of in vitro LIF production by Con-A stimulated mononuclear cells.

LIF activity production by ConA-stimulated mononuclear cells was tested by measuring granulocyte migration from clotted plasma droplets placed in Microtest II plates. 90 min. incubation of MNC cultures with ConA assured a significant LIF activity in the 24 h. culture supernatants. Removal of the adherent cells after ConA pulse exposure improved (p less than 0.05) LIF production. Enrichment with adherent cells of MNC cultures before ConA stimulation decreased LIF release. Irradiation (600 rad) of ConA stimulated MNC cultures, however, abrogated both phenomena induced by either removal or enrichment of the adherent cells. Indomethacin, when added during ConA pulse exposure to adherent cell rich MNC cultures, also increased LIF activity production. Both, PGE1 and supernatants of ConA-pulsed monocyte rich cultures had similar LIF impairing effects but the suppressive activity was abolished either by supernatants dialysis or by irradiation of stimulated MNC cultures.