Adoptive transfer of variant-specific resistance to Trypanosoma rhodesiense with B lymphocytes and serum

Mice survive an otherwise lethal infection with Trypanosoma rhodesiense if previously inoculated with irradiated organisms. This resistance demonstrates immunological specificity, since even animals inoculated with irradiated trypanosomes were killed when challenged with trypanosomes of a nonhomologous or variant antigenic type. This resistance could be transferred to syngeneic recipients with serum or B lymphocytes. T lymphocytes had no capacity to transfer resistance. Although mice were protected from active infection on challenge at least 25 days after inoculation of irradiated organisms, this resistance could be transferred with spleen cells for only 10 days after immunization. Resistance could be transferred with serum for a minimum of 25 days after immunization. These studies implicate an antibody-mediated mechanism as having a major role in resistance to T. rhodesiense infections.