Red-cell Adhesion in Trypanosomiasis of Man and other Animals

Abstract

1. The red-cell adhesion phenomenon in trypanosomiasis of man and other animals, first described by Duke and Wallace (1930) and shown by these authors to be due to the presence in the blood of the infected animal of a sub-stance (adhesin) which appears during the course of an infection, has been investigated further. Several strains of T. rhodesiense and T. gambiense have been used for this study.2. Red-cell adhesion of this nature has been obtained with the red blood cells of primates only, thus confirming the earlier finding.3. No relationship appears to exist between red-cell adhesion and isohaemagglutination, or other types of haemagglutination. The removal, by absorption, of the α and β isohaemagglutinins from a human adhesin serum of blood group O, or the removal from a monkey adhesin serum of agglutinins for baboon, rabbit and guinea-pig red cells does not lead to the removal of the adhesin.4. Centrifuging, per se, does not destroy to any appreciable extent the power of trypanosomes to adhere to red cells.5. Trypanosomes which have been freed from plasma by centrifuging and subsequent washing with citrate-Ringer-glucose solution give good adhesion with human or monkey red cells when a fresh adhesin serum or plasma is used. Little or no adhesion is obtained with these washed trypanosomes however, if the adhesin serum is very old or if it has been previously filtered through a Berkefeld filter candle or if the adhesin serum or plasma has been heated at 56° C. for 30 minutes.6. From this and other evidence the conclusion is reached that in addition to the red cells, trypanosomes and the adhesin some other factor (designated the “X” factor) is necessary for red-cell adhesion.7. This “X” factor is present in the serum or plasma of humans, monkeys, baboons, rabbits and guinea-pigs and has properties similar to those of complement. It is removed, as is most of the haemolytic complement, when the serum is filtered through a Berkefeld filter, it is destroyed by heating at 56° C. for 30 minutes, and, like haemolytic complement, it is inactivated when the serum is subjected to the action of dilute ammonia for about 1½ hours. Filtration, heating at 56° C. for 30 minutes and dilute ammonia appear to have no significant destructive action on the adhesin.8. The requirements for this red-cell adhesion phenomenon are (a) the red cells of a primate, (b) an adhesin, which is probably an antibody-like sub-stance produced during infection with trypanosomes, (c) trypanosomes of a strain related to that which gave rise to the formation of the adhesin, and (d) a complement-like component (“X” factor) present in the plasma and serum of most, if not all, normal animals.