The differing patterns of antigen release and local retention following anterior chamber and intravenous inoculation of soluble antigen. Evidence that the eye acts as an antigen depot
Wilbanks, G.A.; Streilein, J.W.
Regional Immunology 2(6): 390-398
1989
ISSN/ISBN: 0896-0623 PMID: 2485688 Document Number: 333599
The route by which antigen is administered plays an important role in dictating quantitative and qualitative characteristics of systemic immune responses. Antigens such as BSA injected into the anterior chamber (AC) of the eye evoke a deviant systemic immune response (anterior chamber-associated immune deviation-ACAID) characterized by a selective deficiency of delayed hypersensitivity (DH). It has been claimed that the deviant immunity which follows an AC injection is related to the uniqueness of the route of antigen administration. However, others have argued that since the aqueous humor which fills the AC of the eye drains directly into the venous circulation, and since the anterior chamber lacks demonstrable lymphatic drainage pathways, an AC injection is a de facto intravenous (i.v.) injection. To determine which of these proposals is correct, we have studied the kinetics of antigen retention and release following inoculations of 125iodine-labeled BSA into the subconjunctival space (SC), and into the blood stream. The results indicate that both AC and the SC inoculation sites function as antigen depots: significant amounts of BSA are retained within the eye in both situations for at least 4 weeks. Moreover, BSA was released from the eyes into the blood stream for greater than 21 days post-inoculation. Site of i.v. inoculation exhibit no such properties. Interestingly, removal of the eye of AC inoculated groups, but not the site of i.v. inoculation in i.v. recipients, up to 5 days post-inoculation prevented the induction of immune deviation. Thus, intravenous and intracameral injections deliver antigen to the immune system in very different ways, and this difference may account for the distinctly different modes of down-regulation elicited by these two injection routes. Since SC inoculations of antigen induce vigorous DH, whereas AC injections induce impaired DH, the depot effect that follows both SC and AC antigen injections cannot, by itself, account of the deviant immunity that is observed in the latter instance. Arguments are advanced in support of the proposal that both the depot effect and the unique microenvironment of the AC contribute to the unique deficiency of cell-mediated immunity that characterizes systemic immune responses following AC inoculation of antigen.