Potentiation of MIF production by lymphocytes of Trichinella spiralis-infected mice.

In order to further investigate the mechanism involved in the immunopotentiation following Trichinella spiralis infection, mice were injected intraperitoneally with either heat-killed or viable bacillus Calmette-Guérin (BCG) 28 days after oral infection with 200 nematode larvae. Delayed-type hypersensitivity (DTH) was assessed 28 days later by measuring levels of migration inhibitor factor (MIF) elicited by Old Tuberculin challenge. Sensitization with killed BCG produced only negligible amounts of MIF; however, prior T. spiralis infection resulted in significantly increased titers of MIF, reaching levels induced by viable BCG. The data indicated that a lymphokine component may be involved in addition to non-specific mechanisms previously proposed.