Rotatable images showed a close contact between two differently labeled cells. == Conclusions == Intravitreal injection of labeled antibodies can be adapted to visualize labeled cells in the cornea. for OVA, MHC-II, B7-1, or B7-2. Rotatable images showed a close contact between two differently labeled cells. == Conclusions == Intravitreal injection of labeled antibodies can be adapted to visualize labeled cells in the cornea. APCs with unique morphologies, phenotypes, and distribution may contribute to the immunologically privileged feature of the cornea. == Introduction == Antigen-presenting cells (APCs), such as dendritic cells (DCs), macrophages, and B cells, serve as the immune sentinels to the foreign world. DCs are characterized by expression of major histocompatibility complex (MHC) molecules, a dendritic appearance, and the capacity for presenting antigens [1-3]. They are more potent than macrophages in initiating and perpetuating secondary immune responses, and play a pivotal role in immunity and immune tolerance [4]. Macrophages are another important populace of APCs. These cells are involved not only in antigen presenting processes and phagocytosis [5], but also in immune regulation in other organs and tissues due to their active secretion of a range of important biologically active molecules Cytisine (Baphitoxine, Sophorine) [6,7]. It Cytisine (Baphitoxine, Sophorine) has been shown that costimulatory molecules B7-1 and B7-2 are expressed on the surface of APCs and are involved in the activation of T cells. APCs with B7-1 mainly activate Th1 cells, whereas APCs with B7-2 activate Th2 cells and induce immune tolerance by generating IL-10 and IL-4 [8,9]. A recent study has shown that B7-1 and B7-2 are crucial in the induction of anterior chamber-associated immune deviation (ACAID), a systemic tolerance induced by injection of soluble antigen into the anterior chamber of the eye [10]. Therefore, it seems likely that under certain conditions, B7-1 and/or B7-2 not only promote activation of T cells but also participate in the induction of immune tolerance. APCs have been found in ocular tissues such as the uveal tract [11-13], retina [14-16] and cornea [17-19]. The majority of the bone marrow (BM)-derived cells in the mouse iris-ciliary body was shown to be of macrophage and DC lineage. These APCs, particularly F4/80+monocytes/macrophages, have been proposed as one of the immune regulatory components within the anterior segment of the eye that is involved in the induction of ACAID [20,21]. Moreover, as a soluble protein, ovalbumin (OVA) can be Cytisine (Baphitoxine, Sophorine) ingested, processed, and offered by professional APCs. The processing velocity of OVA inside APCs is usually sufficiently slow to allow OVA to serve as an effective tracer reagent to study the characteristics of APCs [22]. In view of the fact that the cornea directly contacts the external environment, it is important to address the role of APCs in this tissue. Previous studies examining the cornea for APCs have largely relied around the expression of MHC-II antigens. The MHC-II+cells were primarily found in the limbus and peripheral cornea of the guinea pig, hamster, mouse, and human [17-19,23-26]. However, the phenotype of these cells and their presence in the central cornea remains controversial [23,27-29]. Recent studies [30,31] recognized unique subtypes of DCs with either BM-derived DC or Langerhans cell Rabbit polyclonal to RAD17 characteristics in the murine corneal tissues. Brissette-Storkus et al. [32] have shown that this BM-derived cells that predominantly reside in the cornea stroma are macrophages. However, the phenotype, distribution, and morphological feature of APCs in the murine cornea have not been well characterized. To address these issues, the present study extensively examined murine corneal APCs by combining intravitreal injection of fluorescently tagged OVA and antibodies, intravital microscopy, whole mount ocular tissue processing, and confocal microscopy techniques..