Side effects of the trypanocidal chemotherapeutics trypan blue and suramin.

Both the uptake of C3-opsonized and of nonopsonized bakers' yeast is inhibited by 1 mM trypan blue. This effect may be explained by inactivation of the C3bi-receptor. But trypan blue also inhibited the uptake of other non-opsonized particles lacking specially binding domains for this receptor. - Suramin has antiphagocytic properties at 1 mM concentration which were explained by its anticomplementary activity. However, the uptake of nonopsonized particles is also inhibited by suramin. The importance of these effects for therapeutic utilization is discussed.