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

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&#176; 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. [ABSTRACT FROM AUTHOR]