Depression of the plaque-forming cells to sheep red blood cells by the new-born larvae of Trichinella spiralis.

The number of plaque-forming cells (PFC) per spleen is reduced in mice experimentally infected with 200 Trichinella larvae at 14 and 28 days after infection, whereas no difference is shown at days 7 and 56. The worms of the three different phases of the life cycle of Trichinella have been isolated and kept alive in vitro at 37 degrees in the inner compartment of a Marbrook chamber. The outer compartment of the chamber contained normal spleen cells and sheep erythrocytes. After 4 days, the spleen cells were removed and assayed for PFC. The results indicate that the new-born larvae are capable of producing substances which can diffuse through a Millipore filter and affect the spleen cells forming antibody to sheep erythrocytes. The suppression of antibody to sheep red blood cells in mice infected with Trichinella is a transitory phenomenon and can be related to the migrating phase of the life cycle of the parasite.