In vivo and in vitro responses to sheep erythrocytes by lymph node cells from mice with trichinellosis.

Mice infected with Trichinella spiralis for 20 days have decreased numbers of plaque forming cells (PFC) in the draining lymph nodes following subcutaneous immunization with sheep erythrocytes. However, when immunized in vitro, lymph node cells from infected mice generate more PFC than normal controls. Splenectomy has no effect on suppression observed in vivo. There is a large increase in the proportion and numbers of B cells in the lymph nodes of infected mice, and these cells may account for the enhanced PFC responses in vitro.