Immune corneal rings. II. Diffusion kinetics of equine albumin in the rabbit cornea.

Intracorneal microinjections of foreign protein, conjugated to 1-131 as radioactive tracer, ivere diminished initially to an average of 71 per cent of the amount injected. After the fint day as little as 14 per cent of the intended inoculum remained. However, this did not constitute true diffusion but early leakage of protein through the needle track. The remainder was slowly lost by diffusion at a rate of 10 per cent per day. A preliminary sensitization with 4 mg. of protein intracutaneously 2 weeks prior to the injection of albumin intracorneally did not alter the rate of diffusion. This was true in spite of the occurrence of marked corneal inflammation during measurement of radioactivity. Mechanical trauma to the cornea when the diffusion of protein has achieved a constant rate did not alter this rate. The mechanism of formation of "systemic immune rings" was postulated to occur when the concentration of antigen had dropped to optimum levels for precipitation by specific serum antibody migrating in from the limbus. The precipitation served to attract inflammatory cells in from the limbal circulation, thereby intensifying the ring reaction and explaining the phenomenon of centripetal ring migration.