A NEW EXPERIMENTAL APPROACH TO THE STUDY OF THE RÔLE OF THE RETICULO-ENDOTHELIAL SYSTEM IN THE CURE OF TRYPANOSOMIASIS

¹ From the Department of Pharmacology of the University of Wisconsin, Madison, Wisconsin

If trypanosomes are treated in vivo for five minutes with 5 mgm. per kilogram mapharsen and the rat's blood then placed in a test tube, the trypanosomes do not die or disappear in fifteen minutes as they do in vivo, but continue to live on for eighty minutes.

The same is true if the rat is killed five minutes after treatment, when the trypanosomes instead of disappearing from the dead host in fifteen minutes may be found and are still infective for an average of seventy-five minutes.

Transplants of the organs of a treated rat taken at the time of disappearance of the trypanosomes from the blood stream indicate a greater accumulation of trypanosomes in the liver than in any other organ.

Acute experiments in which the liver, spleen and kidneys are ligated support the above data in that the ligation of the liver is the only procedure which materially lengthens the disappearance time. The undoubted rôle played by the spleen under other experimental conditions appears to be eclipsed by the activity of the liver under the conditions described in this report.

Since the drug has no effect on "arsenic resistant" trypanosomes in vivo, the logical conclusion is that mapharsen intoxicates the normal trypanosomes which are then removed from the circulating blood and subsequently destroyed through the activity of the reticulo-endothelial system.