The Accumulation of Iron in Tuberculous Areas.

Abstract

In previous communications 1 , 2 , 3 it was shown that a vital dye, trypan blue, or a metal in the form of its salt, ferric chloride, when injected into the circulating blood stream rapidly accumulates in an area of inflammation, where the substance is fixed and fails to drain to the tributary lymph nodes.

Bowman, Winternitz, and Evans by microscopic studies 4 found that, in experimental tuberculosis, trypan blue injected intravenously stains tubercles in the liver. They pointed out the great affinity of giant and epithelioid cells for this vital dye, which was always found as granules within these cells. Lewis 5 found that if the cornea of a rabbit is inoculated with a living culture of the tubercle bacillus, a progressive lesion results characterized by an intense congestion of the conjunctiva. If the animal is given an intravenous injection of trypan red 24 hours or more after such inoculation, the fluid in the anterior chamber of the inoculated eye always becomes colored.

In view of the observation that iron, intravenously injected, accumulates in inflamed areas, a few experiments were set up to determine whether this metal when injected into the circulating blood stream would accumulate and be detected in tubercles.

Bovine tuberculosis was induced in several rabbits by the intravenous injection of 0.001 mg. of a saline suspension of Ravenel strain. From 4 to 5 weeks later extensive tuberculosis had developed in the lungs of most of the animals. These rabbits were given several daily intravenous injections each consisting of 5 cc. of a 0.25% solution of ferric chloride crystals. Three animals were killed after 3, 4 and 7 injections of ferric chloride. The lungs were carefully removed and dipped in acidified potassium ferrocyanide (3 parts of 1% HCl to one part of 2% K₄FE (CN)₆).