Stimulation of blastic transformation of rabbit lymphocytes by means of endotoxins of Bacteroides fragilis.

Blastic transformation of lymphocytes from peripheral blood of rabbits immunized with formolized suspensions of Bacteroides fragilis was obtained. Stimulation was accomplished by means of endotoxins extracted from the strain with which the animals were immunized, and from a related serotype. Blastic transformation was obtained 21 days after the start of immunization of the animals, and maximum response after 4-5 weeks. Humoral response, checked by the passive hemagglutination test, preceded cellular response by 14 days.