A reconsideration of immunological privilege within the anterior chamber of the eye.

The immunologically privileged status of the anterior chamber of the eye has been confirmed on the basis of skin and thyroid allografts with use of inbred strains of rats. Skin grafts, transplanted across both major and minor histocompatibility barriers, enjoy prolonged survival within the anterior chamber. However, several factors have been found to restrict the privilege exhibited by this site: the magnitude of the immunogenetic disparity between donor and recipient, graft size, type of tissue grafted, and, at least in the case of thyroid grafts, the endocrine status of the host. Although a defect in the afferent limb of the immune response has been the popular explanation offered for immunological privilege in an alymphatic site, this was not the basis of the privilege encountered in the anterior chamber. Furthermore, because the efferent limb of the immunological reflex are within the anterior chamber has been demonstrated to be intact, it was suggested that the unique properties of the anterior chamber may depend upon the forced intravascular presentation of antigen and consequent aberrant central processing.