REACTIONS OF RABBITS TO INTRACUTANEOUS INJECTIONS OF PNEUMOCOCCI AND THEIR PRODUCTS : VI. HYPERSENSITIVENESS TO PNEUMOCOCCI AND THEIR PRODUCTS.

1. Rabbits receiving either intracutaneous or intravenous injections of crystalline egg albumin acquire a "skin sensitivity" but not an "eye sensitivity" to the albumin. 2. Rabbits receiving either intracutaneous or intravenous injections of the "nucleoprotein" of Pneumococcus acquire a specific "skin sensitivity" to the "nucleoprotein" but not an "eye sensitivity." 3. Rabbits receiving intravenous injections of a suspension of heat-killed pneumococci acquire a "skin hypersensitiveness" but not an "eye hypersensitiveness" to the "nucleoprotein." 4. The skin hypersensitiveness to the respective proteins is associated with the presence of antibodies in the blood and is transferable by the injection of serum from an actively sensitized to a normal rabbit. 5. Rabbits receiving intracutaneous injections of a suspension of heat-killed pneumococci also acquire a "skin hypersensitiveness" to the "nucleoprotein" of the cell, but they may acquire an eye hypersensitiveness as well. 6. Rabbits injected intracutaneously with a suspension of heat-killed pneumococci show a primary and a secondary skin reaction following the first injection. The intensity of the reactions increases with subsequent injections up to the fourth to the sixth injection. With later injections these reactions change in character and decrease in intensity. These reactions bear no apparent relation to the presence of antibodies in the blood. 7. Rabbits injected intracutaneously with a suspension of heat-killed pneumococci develop "eye hypersensitiveness" which, under the experimental conditions, is not transferable from "eye reactive" to normal rabbits. 8. It appears, therefore, that following the injection of heat-killed pneumococci into the skin a special kind of "eye" and "skin hypersensitiveness" develops which is not related to the presence of circulating antibodies and which cannot be transferred from the sensitive to normal rabbits.