Chronic and acute trypanosomiasis in mice: a study by in vitro cloning of lymphohaematopoietic progenitors.

A semi-solid culture system was used to study the effects of trypanosome infection in two species of mice on the propagation of progenitor cells from the bone marrow and spleen. The deer mouse (Peromyscus maniculatus) survived infection with Trypanosoma (T.) equiperdum for more than 15 days. During the first 10 days there was inhibition of development of granulocyte-monocyte colonies from progenitor cells in the bone marrow. B-lymphocyte progenitors in the spleen showed increased activity, producing colonies 140-300% above normal control groups during the same period. - Conversely, all Balb/c mice infected with the trypanosomes died within 10 days with fulminating parasitemia and massive spleen enlargement. There was a general activation of progenitor cells; B-lymphocytes from the spleen and bone marrow and granulocyte-monocyte colonies from bone marrow, although this was not sustained more than 4 days after infection. - In chronically infected deer mice the pattern of response of the bone marrow and spleen progenitor cells was significantly different over successive weekly intervals. Periodicity of response in these organs was displayed by recurring waves of activation and depression of the progenitor cells. - Thus, there were significant differences in response patterns of deer mice and Balb/c mice to T. equiperdum infection which could be established by the behavior of host lymphohaematopoietic progenitor cells in culture. We therefore suggest that such in vitro cultures may be useful in assessment of the immune response to trypanosomiasis by the host and also for the study of the pathology of both chronic and acute trypanosomiasis.