Diversity of complement-mediated immune reaction to Trypanosoma gambiense.

Intact and papain-treated Trypanosoma gambiense clone populations, each expressing special antigens on their cell surfaces, were mixed with rabbit antiserum in the presence of complement. Two distinct types of immune reaction between trypanosomes and antisera were observed: clumping followed by dissociation (CD) and inhibition of aggregation (IA). Special antigens on the cell surface of trypanosomes exposed after papain digestion are implicated in both types of immune reaction. IA was considered to be more effective as an immunological response which would allow the infected host to clear the pathogen without any obstruction of capillaries and impairment of blood flow caused by clumping masses of trypanosomes.