Suppression of mitogen-induced proliferation of normal spleen cells by macrophages from chickens inoculated with Marek's disease virus

Spleen cells from chickens 7 days after inoculation with Marek's disease virus (MDV) responded poorly to stimulation by phytohemagglutinin (PHA). Addition of these cells to syngeneic normal spleen cells caused a marked suppression of the PHA response of the normal cells. The MDV spleen cells also inhibited the DNA synthesis of MSB-1 lymphoblastoid cells in vitro. The suppressive activity is attributed to the presence in MDV spleen cells of a population of suppresor cells with characteristics typical of macrophages. The suppressor cell activity was not removable by treatment with anti-T or anti-B serum with C, but it was reversible by treatment with carrageenan or carbonyl iron/magnet, by passage through glass wool column, and by adherence to plastic Petri dishes. The adherent MDV spleen cells also showed strong suppressor cell activity against syngeneic normal spleen cells.