Abstract
A biologic method has been devised for identifying a specific skin-reacting substance in the blood serum of tuberculous patients and animals. The point of departure was an earlier observation reported elsewhere 1 that sensitization in normal guinea pigs could be accomplished with fractional tuberculins prepared from non-protein substrates.
Duplicate series of healthy white guinea pigs, weighing 450 to 500 grams, were used in each set of experiments. These were grouped as follows:
(1) Normal guinea pigs previously injected with tuberculin fractions.
(2) Normal, untreated guinea pigs, and
(3) Tuberculous guinea pigs with early, moderately advanced, and far advanced infections.
The animals were tested with (a) human sera from early and far advanced tuberculosis, (b) same sera heated at 60 to 65° C. on a water-bath for 45 minutes, (c) normal human serum, (d) guinea pig serum from early and moribund stages of tuberculosis. Intracutaneous injections of 0.02 cc. of each serum were given for each test. The guinea pigs of the first series were injected subcutaneously with increasing doses of one of the fractional tuberculins over a period of 7 weeks, receiving a total amount of 2.2 cc. of each substance. Ten to 14 days after the last injection, intracutaneous tests were applied with the materials described. Reactions were recorded after 24, 48, and 72 hours, and observations made until the sites of injection appeared normal.
Groups of normal, sensitized, and tuberculous guinea pigs react differently toward intracutaneous injections of minute amounts of blood serum from tuberculous patients or animals. The specific skin reactions appear to depend upon the stage of infection to which the serum corresponds.
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