Suppression of t lymphocyte proliferation by peritoneal macrophages in chickens

The mechanism of the suppression of lymphocyte proliferation by peritoneal macrophages (MPs) in chickens and the presence of a suppressive substance in the culture supernatant of MPs were studied. The results showed that gelatin- and pepton-induced peritoneal MPs had an inhibitory accessory function against blastogenesis of mitogen-stimulated splenic lymphocytes and that resident peritoneal MPs had an enhanced accessory function. The suppressive factor produced by gelatin-induced peritoneal MPs is a protein having a pI of 3.6 and a molecular weight of 64,000 and it is physically and chemically a relatively stable substance. Moreover, it has no cytotoxic effect against lymphocytes and it was verified that the suppressor in the culture supernatant of MPs was not prostaglandin E 2 or α-acid glycoprotein.