Immunological clearance of 75Se-labelled Trypanosoma brucei in mice. II. Mechanisms in immune animals.

Using trypanosomes labelled with [75Se]-methionine a series of experiments was conducted to investigate the respective roles of antibody, macrophage activtion and complement in the removal of trypanosomes from the circulation of immune mice. It was found that clearance in such animals is largely accomplished by antibody-mediated hepatic phagocytosis, which, at least in passively immunized animals, is dependent on opsonization involving C3. No evidence was found to suggest that intravascular lysis or activated macrophages are involved in immune clearance.