Anterior Chamber Injection Research Articles

Thymocytes induced by antigen injection into the anterior chamber activate splenic CD8+ suppressor cells and enhance the antigen-induced production of immunoglobulin G1 antibodies.

Injection of antigen into the ocular anterior chamber (AC) of a mouse eye (an immunologically privileged site) induces the activation of immunoregulatory NK1.1+, CD4- CD8-, T-cell receptor (TCR) alphabeta+ thymocytes. These thymocytes transfer the suppression of delayed-type hypersensitivity (DTH) when injected into mice sensitized to the same antigen but do not effect the suppression of DTH. On the other hand, the immunized recipients of these transferred thymocytes produce splenic CD8+ T cells that effect the suppression of DTH. However, it is unclear whether the thymocytes transferred from the AC-injected donor differentiate into and/or activate CD8+ T-splenic suppressor cells. We therefore sought to determine the origin of splenic suppressor cells produced in the recipients of immunoregulatory thymocytes transferred from donors that receive an injection of antigen into the AC. CD45.1+ thymocytes from mice that received an AC injection of 2,4,6-trinitrobenzene sulphonic acid (TNP)-bovine serum albumin (BSA) were transferred to congenic CD45.2+ TNP-BSA-immune recipients. Spleen cells from the recipients were then sorted based on anti-CD45.1 or -CD45.2 antibody binding and assayed for suppressor cells. This was done by the injection of separated spleen cells into the footpad of TNP-BSA-immunized mice, concurrent with the induction of footpad swelling (contact sensitivity) of the footpad elicited by an epicutaneous application of picryl chloride. The systemic distribution of antigen after the injection of antigen into the AC was demonstrated by the injection of fluorescein or 125I-labelled TNP-BSA into the AC. The results demonstrate that (i) splenic CD8+ T-suppressor cells produced in the immunized recipients of immunoregulatory thymocytes are derived from the CD45.2 recipient of the CD45.1+ thymocytes; (ii) the induction of recipient splenic suppressor T cells by the transferred immunoregulatory thymocytes requires that the recipient be immunized to the same antigen as that used to induce immunoregulatory thymocytes; (iii) antigen is introduced to the thymus after an injection of antigen into the AC; (iv) although the transfer of the suppression of DTH by regulatory thymocytes was not dependent on interleukin-4 (IL-4), CD4+ NK1.1- regulatory thymocytes from AC-injected donors enhanced the production of immunoglobulin G1 antibodies to TNP-BSA by an IL-4-dependent mechanism. These observations suggest that the adult thymus plays an active role in the induction and maintenance of anterior chamber-associated immune deviation as manifested by the generation of the suppression of cell-mediated immunity to exogenous antigen and the antigen-induced production of IgG1 antibodies.

The disposition and bioavailability of 35S-GSH from 35S-GSSG in BSS PLUS in rabbit ocular tissues.

The purpose of this study was to evaluate the biodistribution and uptake of 35S-GSH into intraocular tissues following the administration of BSS PLUS containing 35S-GSSG by either an anterior chamber or intravitreal injection. This study evaluated the disposition and uptake of the 35S-radiolabel, the intracellular concentrations of 35S-GSH from extracellular 35S-GSSG, and the percentage of 35S-GSH to the total cellular GSH pool. Glutathione was analyzed by high-performance liquid chromatography (HPLC) using fluorescence detection after derivitizing the thiols in situ with monobromobimane. The effluent from the GSH peak was then collected for measurement of 35S-GSH. After an anterior chamber injection of 35S-BSS PLUS, 35S-radioactivity rapidly disappeared from the aqueous humor between 0.5 and 2 hours; corneal 35S-radioactivity remained constant over time. 35S-GSH was detected in the iris and ciliary body. However, in the cornea, 35S-GSH became the predominant radioactive thiol in the stroma, endothelium, and epithelium; the corneal stroma appeared to be a possible GSH reservoir for the adjacent corneal layers. After an intravitreal injection, 35S-radioactivity slowly decreased in the vitreous humor but was readily taken up by the tissues of the posterior segment, especially the retina and choroid, which showed the greatest concentrations of 35S-GSH of all tissues studied. The data from this study demonstrate that 35S-GSSG in BSS PLUS is metabolized and taken up by ocular cells and that 35S-GSH becomes incorporated into the intracellular GSH pool of ocular tissues.

APCs in the anterior uveal tract do not migrate to draining lymph nodes.

The migration of APCs from sites of infection and their maturation are critical elements in the generation of immune responses. However, the paths by which intraocular Ags migrate to draining lymph nodes are not known because the eye has limited lymphatic vessels. To date, only dendritic cells from the cornea and conjunctiva have been shown to emigrate. We demonstrate that phagocytic APCs in the anterior uveal tissues of the murine eye that ingest fluorescent latex beads do not migrate to regional lymph nodes. The beads are ingested in the uveal tract by cells expressing MHC class II, CD11c, or F4/80. Using intravital time-lapse videomicroscopy to monitor iris APC migration after anterior chamber injection of fluorescent Ag, fluorescently labeled APCs fail to move at multiple observation times, even in the presence of Ag and LPS. Whereas an as yet unidentified ocular nonphagocytic APC subset might migrate from the anterior uveal tissues, it is more probable that immune responses in the draining lymph nodes are engendered by soluble Ag escaping the eye through interstitial spaces. The inability of anterior uveal tissue APCs to migrate to lymph nodes may contribute to deviant immune responses that dominate after Ags are introduced into the anterior chamber.

Delayed-onset, bleb-associated endophthalmitis caused by lecythophora mutabilis

PurposeTo report delayed-onset, bleb-associated endophthalmitis caused by Lecythophora mutabilis. DesignInterventional case report. MethodsDescription of an otherwise healthy woman who developed delayed-onset fungal endophthalmitis associated with a preexisting filtering bleb. ResultsA 57-year-old woman who underwent trabeculectomy with Mitomycin C in her left eye 8 years earlier presented with a 10-day history of pain and decreased vision in her left eye. She underwent anterior chamber and vitreous taps and injection of intraocular antibiotics. Cultures grew the mold Lecythophora mutabilis. The patient underwent treatment with intraocular and systemic antifungal agents, three pars plana vitrectomies, partial iridectomy, and cryopexy to the bleb and angle structures. Four months after her last treatment, her left eye shows no residual infection, and vision corrects to 20/80. ConclusionBleb-associated endophthalmitis caused by L. mutabilis is resistant to amphotericin B but responsive to intravitreal and systemic voriconazole together with pars plana vitrectomy, iridectomy, and cryopexy to the bleb and angle structures.

Splenic B cells act as antigen presenting cells for the induction of anterior chamber-associated immune deviation.

To characterize the role of B cells in the induction of anterior chamber-associated immune deviation (ACAID). An in vitro model of the ACAID spleen was used to recapitulate the events that occur when antigen is introduced into the anterior chamber of the eye and culminates in the appearance of antigen-specific, CD8(+) suppressor cells. In vitro-generated suppressor cells mimicked those produced by anterior chamber injection of antigen, as shown by their antigen specificity, surface expression of CD8, and capacity to suppress DTH, which is mediated by previously immunized T cells. B cells were found to be necessary for suppressor cell development. The B cell receptor (BCR) was necessary for the induction of ACAID and conveyed antigen specificity to the suppressor T cells. Lysosomal acidification of internalized antigen was necessary for B cells to induce ACAID; however, transporter of antigen processing (TAP) was not required for the generation of ACAID. The results suggest that B cells use the BCR to capture and internalize antigen from ACAID-inducing macrophages. Lysosomal acidification of the captured antigen is essential for the processing of the ACAID antigen before TAP-independent presentation to suppressor cells.

Local Retention of Soluble Antigen by Potential Antigen-Presenting Cells in the Anterior Segment of the Eye

To determine the capacity of bone marrow-derived cells in the anterior segment of the eye to capture a fluorescence-labeled antigen (Ag) injected into the anterior chamber (AC). Uveal tract and corneoscleral tissues from Lewis rats were cultured in vitro, with or without FITC-dextran (4 microg/mL final concentration), for 48 hours and examined by confocal microscopy. To investigate antigen uptake in vivo 2 microL (20 microg) of Cascade Blue-labeled dextran (CB-Dx) was injected into the right AC of Lewis rats. The density of Ag-positive cells in the iris at 1, 3, 5, or 12 days after injection was examined by in vivo video fluorescence microscopy. The distribution and phenotype of Ag-positive cells in frozen and paraffin-embedded sections of ocular tissues and in iris wholemounts from animals killed at 24 hours and day 7 were analyzed by fluorescence and confocal microscopy. In organ culture conditions numerous cells in the iris, ciliary body, choroid, and corneal limbus were capable of capturing fluorescence-labeled Ag. In vivo observations and microscopic examination of experimental eyes at days 1 and 7 after AC injection revealed Ag-positive cells within the iris, iridocorneal angle, the suprachoroidal space and around limbal-episcleral vessels. Ag-bearing cells in the iris express combinations of macrophage markers but rarely expressed major histocompatibility complex (MHC) class II molecules. A reduced number of Ag-bearing cells were still present in the iris at day 12. Potential antigen-presenting cells (APCs) in the iris and ciliary body are capable of internalizing intracameral Ag. The characteristics of these cells in the iris are consistent with a predominantly macrophage phenotype. These observations also suggest that the Ag leaving the eye through both the conventional and nonconventional aqueous outflow pathways may be captured by potential APCs in the episcleral tissues.

A Deviant Immune Response to Viral Proteins and Transgene Product Is Generated on Subretinal Administration of Adenovirus and Adeno-associated Virus

The immune response after ocular exposure to foreign antigens varies substantially from that of a typical systemic response. Anterior chamber associated immune deviation (ACAID) has been well documented. The immune response of the subretinal space has not been studied in as much detail. Here, we characterized the immune response of the subretinal space when it encounters the antigens AdV-GFP and AAV-GFP (recombinant adenovirus or adeno-associated virus, respectively), each delivering the reporter gene encoding green fluorescent protein (GFP). Results indicate that the subretinal space possesses an immune-deviant property similar to ACAID. AdV-elicited immune responses following subretinal injections are significantly reduced compared with systemic responses elicited by intradermal injections of the same virus. Furthermore, subretinal AdV administration results in transduction of retinal pigment epithelial cells (RPE), which are the potential antigen presenting cells of the retina. This subsequently generates a population of immunosuppressive Th2-type, cytokine-secreting, splenic T cells. This response may be advantageous to the development of ocular gene therapy.

A new technique for repairing descemet membrane detachments using intracameral gas injection.

Descemet membrane detachments are not uncommon following cataract surgery, and large and extensive detachments can have an impressive presentation, with severe corneal edema and marked reduction in visual acuity. Traditional treatment regimens have included observation (with the hopes of spontaneous resolution), anterior chamber injections of air or viscoelastic, transcorneal suturing, and even corneal transplantation for persistent cases. During the past few years, intracameral injection with either sulfur hexafluoride (SF6) or perfluoropropane (C3F8) gas has gained increasing acceptance as an efficient and effective treatment option for Descemet membrane detachments. Previously described techniques of gas injection have required corneal and paracentesis incisions; sterile blades, cannulas, and other instruments; and occasionally, an operating room setting. We describe a simple, safe, and effective technique for intracameral gas injection that can be performed by one person at the slitlamp microscope or in a minor operating room with minimal equipment.

Immune consequences of intraocular administration of modified adenoviral vectors.

To investigate the immune consequences of intraocular administration of modified adenoviral vectors, C57BL/6 normal and retinal degeneration C57BL/6 (rd/rd) mice were immunized with subcutaneous, subretinal, vitreal, or anterior chamber injections of replication-deficient adenovirus (AdV) containing the Escherichia coli beta-galactosidase gene (AdV-LacZ). Fourteen days after the initial inoculation, the animals were immune challenged with an injection of AdV-LacZ in the right ear pinna. Antigen-induced delayed type hypersensitivity (DTH) was measured by determining relative ear swelling. Normal C57BL/6 mice immunized with subretinal, vitreal, or anterior chamber injections did not demonstrate a DTH response. The rd/rd C57BL/6 mice injected in the anterior chamber with the viral construct also did not respond with DTH in a manner similar to normal mice responding to intraocular injection and subsequent challenge. However, the rd/rd C57BL/6 mice immunized by the subretinal or vitreal route did respond to immune challenge with a DTH response. Histologic examination of the eyes showed a lack of infiltration by inflammatory cells. Although these results suggest that the potential for immune consequences is reduced when modified adenoviral vectors are used in the normal ocular environment, these vectors used in the vitreal cavity of rd/rd animals may induce a systemic response to the vectors.

Gamma delta T cells are needed for ocular immune privilege and corneal graft survival.

It has been recognized for over a century that the anterior chamber of the eye is endowed with a remarkable immune privilege. One contributing component is the Ag-specific down-regulation of systemic delayed-type hypersensitivity (DTH) that is induced when Ags are introduced into the anterior chamber. This phenomenon, termed anterior chamber-associated immune deviation (ACAID), culminates in the generation of regulatory cells that inhibit the induction (afferent suppression) and expression (efferent suppression) of DTH. Since gamma delta T cells play a major role in other forms of immune regulation, we suspected they might contribute to the induction and expression of ACAID. Mice treated with anti-gamma delta Ab failed to develop ACAID following anterior chamber injection of either soluble Ag (OVA) or alloantigens (spleen cells). Additional experiments with knockout mice confirmed that mice lacking functional gamma delta T cells also fail to develop ACAID. Using a local adoptive transfer of DTH assay, we found that gamma delta T cells were required for the generation of regulatory T cells, but did not function as the efferent regulatory cells of ACAID. The importance of gamma delta T cells in corneal allograft survival was confirmed by blocking gamma delta T cells with GL3 Ab before corneal transplantation. While in vivo treatment with normal hamster serum had no effect on corneal graft survival, infusion of anti-gamma delta Ab resulted in a profound increase in corneal allograft rejection. Thus, gamma delta T cells are needed for sustaining at least one aspect of ocular immune privilege and for promoting corneal allograft survival.

Exogenous vasopressin influences intraocular pressure via the V1 receptors

Purpose. To compare central, peripheral, and ocular effects of exogenously given vasopressin on intraocular pressure (IOP) and to identify the related receptor mechanisms of action in rabbits. Methods. Young adult New Zealand albino rabbits were entrained under a daily 12-hour light and 12-hour dark cycle. In the early light period, bolus injections of vasopressin or desmopressin (a specific V 2 receptor agonist) were given either to the central nervous system (CNS) through an implanted cannula to the 3 rd ventricle or to the systemic circulation via the ear vein in conscious rabbits. Changes in IOP and pupil size were monitored for up to 6 hours and dose-response curves were generated. Effects of centrally and peripherally given vasopressin on IOP were further examined following pretreatments with a selective V 1 receptor antagonist administered into the 3 rd ventricle and into the ear vein, respectively. In order to clarify whether or not exogenously given vasopressin can alter IOP by mechanisms inside the eye, vasopressin was injected into the anterior chamber or the vitreous chamber unilaterally in conscious rabbits. Changes in IOP and pupil size were monitored. After an anterior chamber or intravitreal injection of the V 1 receptor antagonist, changes in IOP and pupil size due to an intravenous injection of vasopressin were determined to study the involvement of the related receptor mechanism. Results. A dose-dependent elevation of IOP appeared after injections of vasopressin into the 3 rd ventricle. There was no pupillary change. This IOP elevation was blocked by the pretreatment with the V 1 receptor antagonist. Following intravenous injections of vasopressin, significant reductions of IOP and pupil size occurred. These reductions were blocked by the pretreatment with the V 1 receptor antagonist. Intracerebroventricular or intravenous injection of desmopressin had no effect on IOP or pupil size. Injection of vasopressin into the anterior chamber or the vitreous chamber caused significant reductions of IOP and pupil size. Pretreatment with the V 1 receptor antagonist into the anterior chamber or the vitreous chamber prevented the reductions of IOP and pupil size following an intravenous injection of vasopressin. Conclusions. Intracerebroventricular and intravenous injections of vasopressin cause opposite effects on IOP. The central effect of vasopressin on IOP and the peripheral effects of vasopressin on IOP and pupil size are due to stimulations of the V 1 receptors. Reductions of IOP and pupil size following intravenous injections of vasopressin are at least partially due to stimulations of the V 1 receptors inside the eye.

In-vivo impaired T helper 1 cell development in submandibular lymph nodes due to IL-12 deficiency following antigen injection into the anterior chamber of the eye

To determine the functional properties of antigen-specific T cells that accumulate in lymph nodes following injection of antigen into the anterior chamber (AC). Ovalbumin (OVA)-specific, CD4(+) transgenic T cell receptor (Tcr) T cells (KJ-126(+)) from DO11.10 mice were adoptively transferred into unirradiated syngeneic BALB/c mice who then received an injection of OVA in the AC or subcutaneously (SC). Three days later, KJ126(+) T cells in draining and non-draining lymph nodes were analyzed for clonal expansion, activation, and cell-cycle status by flow cytometry. In addition, the cells' functional phenotype was assessed in vitro by proliferation assays and cytokine production by ELISA. Tcr T cells localized exclusively to draining lymph nodes after injection of OVA into the AC (neck) and SC (neck, axilla, brachial). In both cases, the KJ126(+) T cells displayed evidence of in-vivo activation and proliferation. T cells from AC-injected donors when stimulated in vitro with OVA produced small amounts of IL-2, but no IFN-gamma, IL-4, IL-5, IL-10, or TGFbeta. By contrast, T cells from SC-injected animals displayed a Th1-like phenotype (IL-2, IFN-gamma). The draining lymph nodes of mice that received systemic or intraocular administration of exogenous IL-12 at the time of the AC injection of OVA also contained KJ126(+) T cells that secreted IFN-gamma and IL-2. Antigen attracts antigen-specific T cells to lymph nodes that drain the injection site. Whereas responding T cells in nodes draining SC-injection sites differentiated into Th1-like cells, T cells in nodes draining AC injection failed to differentiated beyond the capacity to secrete IL-2 in response to antigen. Since the failure was reversed by exogenous IL-12, we propose that orderly differentiation of antigen-specific T cells down the Th1 pathway is aborted by the eye, because of a deficit in IL-12 production.

Evidence for multiple CD95-CD95 ligand interactions in anteriorchamber-associated immune deviation induced by soluble protein antigen.

We have investigated whether CD95-CD95 ligand interactions are important in anterior chamber-associated immune deviation (ACAID) induced by soluble protein antigen, and if so, to identify the participating cells on which these molecules are expressed. Peritoneal exudate cells as antigen-presenting cells (APC) obtained from B6.lpr/lpr, B6.gld/gld and C57BL/6 mice were cultured with ovalbumin (OVA) and transforming growth factor-beta2 (TGF-beta2) overnight, then injected intravenously into C57BL/6 or B6.lpr/lpr recipients. Some B6.lpr/lpr mice were reconstituted with naive T cells from wild-type C57BL/6 donors. In other experiments, B6. lpr/lpr and B6.gld/gld mice received an anterior chamber injection of OVA followed 7 days later by subcutaneous immunization with OVA plus adjuvant. Delayed hypersensitivity (DH) was assessed with an ear swelling assay. T cells activated in vitro with OVA-pulsed, TGF-beta-treated APC were tested in vivo for their capacity to suppress DH expression in a local adoptive transfer assay. The results indicate that when ACAID was induced by in-vitro generated ACAID-inducing cells, the APC expressed CD95L, and recipient T cells expressed CD95. The capacity of in vitro generated regulatory T cells to suppress DH expression to OVA in vivo was not governed by CD95-CD95L interactions. When OVA was injected into the anterior chamber of naive mice, CD95 expression was required for ACAID induction, although ACAID was readily induced in CD95L-deficient mice. We conclude that CD95-CD95L interactions are required in ACAID for the initial stage of APC presentation of eye-derived antigens to T cells, and that CD95-CD95L interactions participate at one or more additional step in the process by which ACAID is induced by soluble protein antigens.

In-vivo impaired T helper 1 cell development in submandibular lymph nodes due to IL-12 deficiency following antigen injection into the anterior chamber of the eye

Purpose: To determine the functional properties of antigen- specific T cells that accumulate in lymph nodes following injection of antigen into the anterior chamber (AC). Methods: Ovalbumin (OVA)- specific, CD4 + transgenic T cell receptor (Tcr) T cells (KJ-126 + ) from DO11.10 mice were adoptively transferred into unirradiated syngeneic BALB/c mice who then received an injection of OVA in the AC or subcutaneously (SC). Three days later, KJ126 + T cells in draining and non-draining lymph nodes were analyzed for clonal expansion, activation, and cell-cycle status by flow cytometry. In addition, the cells’ functional phenotype was assessed in vitro by proliferation assays and cytokine production by ELISA. Results: Tcr T cells localized exclusively to draining lymph nodes after injection of OVA into the AC (neck) and SC (neck, axilla, brachial). In both cases, the KJ-126 + T cells displayed evidence of in-vivo activation and proliferation. T cells from AC-injected donors when stimulated in vitro with OVA produced small amounts of IL-2, but no IFN-?, IL-4, IL-5, IL-10, or TGFß. By contrast, T cells from SCinjected animals displayed a Th1-like phenotype (IL-2, IFN-?). The draining lymph nodes of mice that received systemic or intraocular administration of exogenous IL-12 at the time of the AC injection of OVA also contained KJ-126 + T cells that secreted IFN-? and IL-2. Conclusion: Antigen attracts antigen-specific T cells to lymph nodes that drain the injection site. Whereas responding T cells in nodes draining SC-injection sites differentiated into Th1-like cells, T cells in nodes draining AC injection failed to differentiated beyond the capacity to secrete IL-2 in response to antigen. Since the failure was reversed by exogenous IL-12, we propose that orderly differentiation of antigen-specific T cells down the Th1 pathway is aborted by the eye, because of a deficit in IL-12 production.

Recombinant tissue plasminogen activator in cases with fibrin formation after cataract surgery: a prospective randomised multicentre study

AIMSThis study investigated the effect of tissue plasminogen activator (tPA) in patients with severe intracameral fibrin after extracapsular cataract extraction or phacoemulsification with posterior chamber intraocular lens implantation.METHODSA randomised prospective...

A Novel Role for TGF-β and IL-10 in the Induction of Immune Privilege

Abstract Immune privilege within the eye is due in large part to Ag-specific, systemic down-regulation of Th1 immune responses, a phenomenon termed anterior chamber-associated immune deviation (ACAID). Since the cytokine milieu influences Th cell differentiation, we hypothesized that TGF-β, an immunosuppressive cytokine secreted by ocular cells, determines the nature of the immune response to Ags introduced into the anterior chamber. Accordingly, an in vitro model of the eye was used to determine the cytokine profile of ocular APC. TGF-β preferentially induced APC to secrete a Th2-type cytokine, IL-10, and concomitantly suppressed the production of the Th1-inducing cytokine, IL-12. APC incubated with TGF-β and anti-IL-10 Ab lost their ability to induce ACAID. In the absence of TGF-β, Ag-pulsed APC preferentially secreted IL-12 and elicited Ag-specific Th1 responses (i.e., delayed-type hypersensitivity (DTH)). However, APC pulsed with Ag and exogenous IL-10 behaved in a manner similar to ocular APC and induced Ag-specific suppression of DTH. The role of IL-10 in ACAID was confirmed in IL-10 knockout mice. Anterior chamber injection of OVA into IL-10 knockout mice elicited normal DTH responses rather than ACAID. Moreover, Ag-pulsed APC from IL-10 knockout mice were unable to induce ACAID following in vitro treatment with TGF-β. Thus, TGF-β predisposes ocular APC to secrete IL-10 during Ag processing. This, in turn, directs the immune response away from a Th1 pathway and toward a Th2-like response in which DTH is suppressed.

Corneal Endothelial Toxicity of Topical Anesthesia

To determine the relative corneal endothelial toxicities of the following topical anesthetic agents: bupivacaine HCl 0.75%, unpreserved lidocaine HCl 4%, proparacaine HCl 0.5%, and tetracaine HCl 0.5%. The experiment was conducted using pigmented rabbits. Approximately nine animals each were randomly assigned to eight groups. Right eyes received injections of 0.2 ml of one of the four anesthetic agents at one of two concentrations and left eyes received injections of 0.2 ml of balanced salt solution. Corneal thickness and clarity were measured before surgery and on postoperative days 1, 3, and 7. A statistically significant increase (P < 0.05) in corneal thickness and opacification over preoperative measurements was noted with injections of bupivacaine, lidocaine, and proparacaine, controlling for changes occurring in control eyes from surgery alone. Proparacaine was statistically more toxic than were the others. The toxicity of tetracaine was statistically indistinguishable from balanced salt solution, although mild toxicity was evident clinically. Injection of 1:10 dilutions of the same anesthetic agents failed to produce a statistically significant increase in corneal thickness or opacification on any postoperative examination. Anterior chamber injection of bupivacaine HCl 0.75%, unpreserved lidocaine HCl 4%, and proparacaine HCl 0.5% produces corneal thickening and opacification that is clinically and statistically significant. Tetracaine HCl 0.5% injection produces corneal thickening and opacification that is clinically apparent in some eyes but statistically insignificant. Ophthalmic surgeons should be aware of the potential for endothelial cell injury if anesthetic agents enter or are injected into the eye during cataract surgery in the concentrations supplied commercially.

Direct thymic involvement in anterior chamber-associated immune deviation: evidence for a nondeletional mechanism of centrally induced tolerance to extrathymic antigens in adult mice.

Recent reports have suggested that the dichotomy between central (thymic) and peripheral T cell tolerance is not absolute and that self-tolerance in perinatal animals may also involve the intrathymic generation and release to the periphery of Ag-specific immunoregulatory T cells. We have expanded this concept to include tolerance to non self Ags administered extrathymically to adult animals. In this study, we use the anterior chamber-associated immune deviation (ACAID) to demonstrate that central regulation of acquired peripheral tolerance can be induced in adult mice by the intraocular administration of low doses of nonself Ag. The results show that adult thymectomy prevents the inhibition of trinitrophenol (TNP)-specific delayed-type hypersensitivity, which normally occurs after injection of TNP-BSA into the anterior chamber (AC) of the eye. Thymocytes obtained from mice 1 to 3 days, but not 5 to 7 days, after AC injection of TNP-BSA or BSA alone specifically transfer inhibition of delayed-type hypersensitivity to mice primed with the homologous Ag. The latter observation, when correlated with the time of onset of ACAID, suggests that immunoregulatory T cells are formed in the thymus within 24 h and are exported to the peripheral lymphoid tissues between 2 and 5 days after AC injection of Ag. Immunomagnetic separation of thymocytes revealed that the immunoregulatory activity resides within the minor subset of CD4-, CD8-, TCR-alphabeta+ cells, previously postulated to induce fas ligand-mediated apoptosis and Th1 to Th2 immune deviation. Hence, the present study identifies ACAID as a prototypical model of centrally induced, nondeletional tolerance to extrathymic nonself Ags.

Serum TABM produced during anterior chamber-associated immune deviation passively transfers suppression of delayed-type hypersensitivity to primed mice.

Injection of soluble protein antigen into the anterior chamber of the eye of primed mice induces anterior chamber-associated immune deviation (ACAID) which is manifested by suppression of delayed-type hypersensitivity (DTH) to the antigen. Recently, we found that ACAID induced in primed mice also results in a rapid rise in serum of soluble T lymphocyte-derived proteins specific for nominal antigen (TABM). Here, we demonstrate that serum TABM induced in primed mice during ACAID will transfer the suppression of DTH to mice primed to the same antigen. Sera from TNP-BSA-primed mice that received an anterior chamber injection of TNP-BSA, but not BSA alone, suppressed the DTH response to TNP when injected into other TNP-BSA-primed mice. Sera absorbed with Sepharose beads conjugated with either anti-TCR C(alpha), anti-TCR C(beta), anti-TABM or TNP-BSA did not contain TNP-specific TABM and did not transfer suppression of DTH. These results suggest that the antigen-specific, TCR C(alphabeta)+ TABM that appear in serum during ACAID are able to confer on or amplify the capacity of sensitized T cells to suppress DTH. We believe this to be the first demonstration of an in vivo immunologic function that is specifically associated with TABM produced in vivo.

Tissue Plasmmogen Activator for Preserving Inferior Peripheral Iridectomy Patency in Eyes with Silicone Oil

An inferior peripheral iridectomy (IPI) was used to prevent forward migration of silicone oil in vitrectomized eyes; however, in approximately one third of eyes, the IPI closed spontaneously. Occlusion of the IPI by fibrin is believed to be an early event in permanent IPI closure by scar tissue. The authors determined whether intraocular tissue plasminogen activator (tPA) would restore and maintain IPI patency in eyes that had early occlusion of the IPI by fibrin. Between November 1993 and January 1995, 12 patients who underwent vitrectomy with silicone tamponade and IPI for complicated retinal detachment received an anterior chamber injection of tPA (6.25 or 12.5 microgram) for occlusion of the IPI by fibrin. All 12 patients had lysis of fibrin and maintained a patent IPI at the last follow-up (124+/-95 days). One patient required multiple tPA injections for recurrent fibrin formation. In another patient, a small hyphema developed after the tPA injection, which did not occlude the IPI. When compared with the natural course in a very similar group of patients previously reported, tPA had a statistically significant beneficial effect in the maintenance of IPI patency (P = 0.040). Intraocular tPA can be safely used to lyse postoperative fibrin occluding the IPI in eyes with silicone oil tamponade. Early lysis of this fibrin maintains IPI patency.