Resident tissue macrophages within the normal rat iris lack immunosuppressive activity and are effective antigen-presenting cells

Ocul Immunol Inflamm. 2000 Sep;8(3):177-87.


Despite extensive study of the numerous immunoregulatory mechanisms that contribute to the 'immune-privileged'nature of the anterior chamber (AC) of the eye, little is known of the functional nature of antigen-presenting cells (APC) present in the tissues adjoining the AC. In the present study, we have compared the antigen-presenting capacity of dendritic cells (DC) and macrophages isolated from the normal rat iris. Whereas iris DC exhibited a potent ability to stimulate resting allogeneic T cells in MLR cultures (an in-vitro correlate of the ability to induce primary T cell responses), resident iris macrophages displayed negligible MLR-stimulatory capacity. Significantly, iris macrophages could efficiently elicit proliferation of primed antigen-specific T cells (an in-vitro correlate of the ability to act as local APC in secondary responses). This antigen-presenting activity was approximately half that of fully 'mature' iris DC and considerably greater than that of freshly isolated iris DC. A key contributor to the effectiveness of resident iris macrophage antigen presentation was considered to be the absence of lymphocytostatic control of T cell proliferation exerted by these cells. The results indicate dichotomous but complementary roles for DC (immune surveillance) and macrophages (local antigen presentation in secondary responses) in this tissue.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigen Presentation / immunology*
  • Antigens / immunology
  • Cell Separation
  • Cells, Cultured
  • DNA / biosynthesis
  • Dendritic Cells / immunology*
  • Iris / cytology*
  • Lymphocyte Activation / immunology
  • Lymphocyte Culture Test, Mixed
  • Macrophages / immunology*
  • Male
  • Ovalbumin / immunology
  • Rats
  • Rats, Inbred Lew
  • T-Lymphocytes / immunology


  • Antigens
  • Ovalbumin
  • DNA