Ocular anaphylaxis: induction by local injection of antigen

A model of local ocular anaphylaxis has been developed in the rat. Erythema, oedema, and enhanced retention of radioiodinated rat serum albumin ([125I]-RSA) were noted in ocular adnexal tissues of immunized rats within 5 min of injection of antigen; these changes reached a maximum 15 min after antigen injection. Erythema, oedema, and retention of [125I]-RSA subsided to baseline levels 1--6 hr after challenge. A significant increase in weight of ocular adnexal tissues was seen within 15 min after challenge. The weight increase reached a maximum at 45 min and persisted through 6 hr. Weight approached baseline values by 24 hr. Although antigen was injected into the ocular adnexa and not directly into the globe, the globes of the antigen-injected eyes of immunized rats underwent anaphylaxis, possibly because of absorption of antigen through the sclera. In addition, the adnexa and globes of the contralateral eyes, which did not receive antigen, also underwent anaphylactic changes. These changes were not as marked as those observed in the antigen-injected tissues, but followed the same time-course of development. We conclude that anaphylaxis can be locally induced in ocular tissues, that the onset of anaphylaxis is within minutes, and the effects last for at least 24 hr.