Attachment of Trypanosoma brucei to rabbit peritoneal exudate cells

Attachment of trypanosomes to cultured rabbit peritoneal cells was enhanced in the presence of hyperimmune Trypanosoma brucei antiserum and sera from infected rabbits. During infection attachment rose rapidly from control levels reaching a maximum value after two or three weeks; this was maintained until the death of the animal. The initial rise in activity was preceded by an increase in the serum titres of trypanosome agglutinating antibody. Attachment did not appear to be mediated by variant specific antibodies, no association being found between adherence and the appearance of successive variant subpopulations. Fractionation of hyperimmune and immune sera indicated that the majority of activity was present in the gamma globulin fraction with less activity in the macroglobulin fraction, despite its elevation during infection. Increased activity obtained with partially-purified immunoglobulin G prepared from hyperimmune serum was reduced following absorption with either disrupted or live trypanosomes.