Leucoagglutination and cytotoxicity of the serum of infected mice and of extracts of Trichinella spiralis larvae and the capacity of infected mouse sera to prolong skin allografts.

The sera of mice infected with the nematode Trichinella spiralis agglutinate and kill homologous lymphoid cells in vitro. The agglutinating activity is present in the sera of infected animals on the 7th day following inoculation with the parasite, rises to a maximum on the 30th day of the infection and then decreases. The leucoagglutinating titre of these sera is related neither to the level of the inoculating dose of parasites nor to the intensity of muscle infection. The agglutinating and leucotoxic activity of the sera of infected mice is probably due to the same factor(s), but target cells require sensitization before cytotoxicity becomes apparent. Skin allografts were prolonged in infected animals or in animals treated with the serum of infected animals. Saline extracts of T. spiralis larvae also have leucoagglutinating and leucotoxic activity.