Calcification of Tubercles by Administration of Calcium Chloride.

In previous communications 1 , 2 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. Subsequently it was shown in infected rabbits 3 , 4 that repeated daily intravenous injections of ferric chloride are followed by an accumulation of iron in the caseous center of tuberculous areas.

The object of this study was to determine whether calcium would likewise penetrate from the blood stream into tuberculous foci. Such evidence might offer a reasonable explanation for the origin of this element in calcified tubercles. The literature fails to reveal any agreement on the effect of calcium in experimental tuberculosis. Michelazzi 5 found calcification of lesions in tuberculous rabbits treated with calcium. Hoyle, 6 who maintained that these earlier experiments were unsatisfactory, found no appreciable difference in the course of the disease between experimental and control groups. He, however, failed to make histological comparisons. Maver and Wells 7 found in guinea pigs that the amount of calcium in tuberculous lesions is not appreciably modified by adding calcium lactate to the usual diet. Spies 8 recently demonstrated that repeated administration of irradiated ergosterol causes calcification of tubercles.

In our experiments bovine tuberculosis was induced in rabbits by the intravenous injection of 0.01 mg. of a saline suspension of Ravenel strain. From 3 to 4 weeks later several of the rabbits were given daily intravenous injections of 5% CaCl₂, solution. On the first day each animal received 3 cc. of this solution; 4 to 6 cc. was injected on each of the subsequent days. After a variable number of injections these rabbits were killed.