Nutritional and immunological factors in the control of infections with Trypanosoma lewisi

This paper is an attempt to view the infection with T. lewisi as a balance of host nutritional factors to which the parasite is attuned and the host defensive system, which recognizes and attempts to subdue him. The host nutritional factors seem to bring parasite numbers to a high level operating through many log units of growth. The host defense system has far narrower limits and can be overwhelmed by much smaller modifications. An essential feature of the host defense is an exceedingly active lymphomyeloid interaction, so far visualized in the spleen. Here the very proximity of plasma cells and reticular cells affords great opportunities for direct transfer of immunoglobulins without evidence of these molecules as agglutinating antibodies in the blood. This mechanism of active trypanosome venting foci with selectivity for younger forms seems more satisfactory than proposing a unique and unusual antibody system.