Anti-interferon globulin inhibits macrophage phagocytic enhancement in vivo by tilorone or Newcastle disease virus

Poly I:C or IFN-alpha/beta treatment inhibits macrophage induced T cell proliferation

IFN-alpha/beta has been previously shown to cause the suppression of various immune responses. The reason for this immunosuppression, however, remains unknown. The studies described in this report demonstrate that treatment of mice with poly I:C or partially purified IFN alpha/beta inhibited the ability of KLH pulsed macrophages to induce proliferation of KLH immune T cells. This failure to generate antigen induced proliferation was not caused by the production of prostaglandins or other suppressive molecules by IFN treated macrophages, nor did this treatment induce suppressor macrophages.

Mononuclear phagocytes: responders to and producers of interferon

We have provided evidence that in vivo-induced type I IF enhanced Fc-mediated particle uptake by mouse macrophages. Fc-mediated phagocytosis of opsonized erythrocytes by unelicited fresh or cultivated macrophages was stimulated by 4-8 hours of cultivation with 100 ohms/ml IF. A 1-hour pulse was sufficient when followed by incubation in If-free medium. Pactamycin, a protein synthesis inhibitor, and camptothecin, and RNA synthesis inhibitor, blocked the stimulation of phagocytosis, indicating a requirement for macromolecular synthesis. Binding by the macrophages of a radioiodinated monoclonal antibody with anti-Fc receptor II specificity indicated that the stimulation of phagocytosis did not result from an increase in the numbers of available Fc receptors. Inflammatory macrophages, while more phagocytic than resting cells, could be further stimulated by IF in vitro, as could macrophages stimulated with LPS. In contrast, macrophages obtained from animals treated with IF inducers could not be further stimulated by IF. LPS-prestimulated and normal macrophages showed similar time-course and dose-response curves to IF, indicating that the probable mechanism of stimulation is similar in both types of cells. Cultivated bone marrow-derived macrophages found to be sensitive to IF induction by LPS, poly I.C., or NDV. The induction of IF by either LPS or poly I.C. was greater at 26 degrees C than at 37 degrees C, while no such difference was found using NDV. A 2-hour pulse of LPS was sufficient to induce IF in marrow-derived macrophages. The induced IF activity was shown to be type I IF.