Immune Tissue Response to Non-hemolytic Streptococci.

We 1 originally reported that if a rabbit had been recently inoculated by any route with streptococci of any type it would fail to show a secondary reaction following intracutaneous inoculation with suitable strains of streptococcus viridans. This might be due to one of two conditions: first a hyperergic, second an immune state. First, if due to a hyperergic state there might be a combination of accelerated hyperergic-secondary-reaction with the primary reaction; hence the initial response to introduction of the same sized inoculum would constantly increase up to a certain point. Second, if an effective immune state had been induced, the local protective mechanism against the inoculum might be so efficient that the sum of the primary and accelerated secondary reactions would be smaller than the initial response of a normal animal.

These two states were easily demonstrated in rabbits, according to the route used for inoculation. When repeated intracutaneous injections were made of 0.1, 0.01 and 0.0001 cc. at the time of each inoculation, the intensity of the local reaction at the site of each injection increased, up to a certain limit. Another group of rabbits inoculated intravenously showed very much smaller local reactions at the site of test intracutaneous inoculations. For example, at the site of a 0.0001 cc. inoculation there was only a slight erythema or a hard nodule 3 to 5 mm. in diameter, contrasted with a hard infiltrated papule 12 to 15 mm. in diameter, and 1 to 3 mm. in height in a hyperergic animal. In a highly immune rabbit the local reaction to 0.01 cc. was distinctly less than that of a hyperergic animal to 0.0001 cc. Immune animals have not developed interstitial keratitis following corneal inoculation, nor have they shown the lethal, tuberculin shock-like, reaction following intravenous injection.