Biomedical subjects

T A Ferguson

Publications and source records attributed to T A Ferguson.

At least 37 records · Page 2Linked to original sources

PubMed1996

Mice deficient in IL-1beta manifest impaired contact hypersensitivity to trinitrochlorobenzone.

Mice rendered deficient in IL-1 beta by gene targeting in embryonic stem cells develop and grow normally in a protected laboratory environment. Endotoxin-stimulated peritoneal macrophages from IL-1beta-deficient mice showed normal synthesis and cellular release of IL-1alpha after treatment with 5 mM ATP demonstrating that IL-1beta is not necessary for expression and release of the IL-1alpha isoform. Mice deficient in IL-1beta showed unaltered sensitivity to endotoxic shock, with or without pretreatment with D-galactosamine. In contrast, IL-1beta-deficient mice showed defective contact hypersensitivity responses to topically applied trinitrochlorobenzene (TNCB). This defect could be overcome either by application of very high doses of sensitizing antigen, or by local intradermal injection of recombinant IL-1beta immediately before antigen application. These data demonstrate an essential role for IL-1beta in contact hypersensitivity and suggest that IL-1beta acts early during the sensitization phase of response. They suggest an important role for IL-1beta in initiation of the host of response at the epidermal barrier.

Animals↗

PubMed1996

CD95-induced apoptosis of lymphocytes in an immune privileged site induces immunological tolerance.

We examined the relationship between cell death and tolerance induction following antigen injection into the anterior chamber of the eye. Our data show that when inflammatory cells undergo apoptosis following infection with HSV-1, tolerance to the virus was observed. In contrast, when cell death was absent due to defects in Fas or FasL, immune tolerance was not observed. Further studies revealed that cell death and tolerance required that the lymphoid cells be Fas+ and the eye be FasL+. Additionally, we show that while Fas/FasL-mediated apoptosis occurred in the eye, it was apoptotic cell death that was critical for tolerance induction. Our results further demonstrate immune privilege is not a passive process involving physical barriers, but is an active process that employs an important natural mechanism to induce cell death and immune tolerance.

Animals↗

PubMed1996

Regulation of CD95 ligand expression: a key element in immune regulation?

Peripheral deletion of activated T cells has an important function in the regulation of the extent of an immune response. Upon restimulation through the T cell receptor previously stimulated cells have been shown to die by activation-induced cell death. Recent data indicate that this process is mediated by a CD95 (Fas/APO-1)/CD95 ligand interaction which induces apoptosis of the T cell. CD95 ligand (CD95-L) is absent on unactivated T cells but is readily expressed upon stimulation. Here we discuss evidence that CD95-L expression is induced by T cell receptor-mediated signals and is regulated at different levels. Different inhibitors of activation-induced cell death have been found to directly or indirectly act on the signal transduction pathway leading to CD95-L expression. CD95-L seems not only to be induced in T cells after activation but is also found constitutively expressed in many non-lymphoid tissues. This indicates that CD95-L is not only critically involved in activation-induced T cell death, but may have other functions as well. One such function is in the maintenance of immunological privilege, the protection of some tissues from potentially destructive immune responses. Thus, the regulation of CD95 expression in lymphoid and non-lymphoid cells appears to represent a key element in immune regulation.

Animals↗

PubMed1995

Fas ligand-induced apoptosis as a mechanism of immune privilege.

The eye is a privileged site that cannot tolerate destructive inflammatory responses. Inflammatory cells entering the anterior chamber of the eye in response to viral infection underwent apoptosis that was dependent on Fas (CD95)-Fas ligand (FasL) and produced no tissue damage. In contrast, viral infection in gld mice, which lack functional FasL, resulted in an inflammation and invasion of ocular tissue without apoptosis. Fas-positive but not Fas-negative tumor cells were killed by apoptosis when placed within isolated anterior segments of the eyes of normal but not FasL-negative mice. FasL messenger RNA and protein were detectable in the eye. Thus, Fas-FasL interactions appear to be an important mechanism for the maintenance of immune privilege.

Animals↗

PubMed1995

Neuropeptides modulate immune deviation induced via the anterior chamber of the eye.

Ag presentation via the anterior chamber of the eye results in a form of immune deviation termed anterior chamber-associated immune deviation (ACAID). The hallmarks of this response are the suppression of delayed-type hypersensitivity with simultaneous induction of Ab production. In this study, we examined the role of the neuropeptides vasoactive intestinal peptide (VIP) and substance P (SP) and found that the levels of these two peptides are controlled by neurogenic stimulation of the eye by light, and that these molecules determine the outcome of Ag presentation in the eye. Mice reared under diurnal conditions had VIP in the iris and ciliary body (not free in aqueous humor) and low levels of SP. Mice that were reared in the dark (or dark-adapted) did not contain detectable levels of VIP but had high levels of SP. The adaptation of diurnal mice to the dark eliminated VIP and increased SP, while adapting dark-reared mice to the diurnal cycle increased VIP and reduced SP. We then tested the hypothesis that immune reactions resulting from Ag presentation in the eye were linked to SP and VIP. We found that a VIP receptor antagonist, when injected into the eye with Ag, reversed ACAID in diurnal mice, while a SP receptor antagonist restored ACAID to dark-adapted mice. We further determined that injection of Ag or TNF-alpha induced VIP release, while SP was liberated into the aqueous humor following reexposure of dark-reared mice to light. Our results demonstrate a close linkage of intraocular immune reactions to neuropeptide levels in the eye.

Animals↗

PubMed1995

The immune response and the eye. TCR alpha-chain related molecules regulate the systemic immunity to antigen presented in the eye.

Injection of antigen into the anterior chamber (AC) of the eye results in the induction of immune deviation in which antibody production is activated and delayed-type hypersensitivity (DTH) is inhibited. This system is termed anterior chamber associated immune deviation (ACAID) and the model is used to examine certain aspects of the immunologic privilege of the eye. Recent studies have established that following antigen presentation in the eye, an 'ACAID-inducing' signal is produced that directly enters the blood. This signal then homes to the spleen where T cells that down-regulate DTH are activated. For many antigens this 'ACAID signal' is a soluble protein released within 2 days of AC injection. Although the presence of this molecule (or molecules) has been described using several antigens, the exact nature of the soluble mediator has escaped characterization. We have further explored the nature of this signal using HSV-1-induced immune deviation. Our results show the soluble 'signal' was released by T cells that encounter antigen in the ocular microenvironment. This mediator was antigen specific, contained TCR alpha-chain (but not the TCR beta-chain) determinants and had an apparent molecular weight of 46 kDa. These results show that the release of soluble TCR alpha-chain from sites of T cell interaction within the microenvironment of the eye can regulate systemic immune responses. These results have implications for the control of immune response that might be damaging to organs such as the eye.

Animals↗

PubMed1994

Regulation of contact hypersensitivity by interleukin 10.

Contact hypersensitivity (CHS) responses require the participation of T cells, along with a variety of cytokines and adhesion molecules. In the classical CHS, antigen-specific T cells are recruited to a site of antigenic challenge, where they react with antigen, release cytokines, and attract other inflammatory cells. In the mouse model of CHS, this reaction is elicited in sensitized mice by application of the immunogen 4-7 d after immunization. The reaction peaks at 24 h, is slightly reduced by 48 h, and can return to normal by 72 h. This is in spite of the fact that some antigen is still present at the site of challenge. Here we examined the hypothesis that locally produced interleukin 10 (IL-10) regulates the duration of the response. Our data show that IL-10 protein peaked 10-14 h after antigenic challenge and returned to background by 24 h. The production of IL-10 protein corresponded with, and followed IL-10 mRNA transcription as detected by reverse transcriptase-polymerase chain reaction. During peak IL-10 production after antigenic challenge, it was not possible to transfer CHS with immune lymphoid cells, unless neutralizing antibody to IL-10 was given first. Additionally, when sensitized mice were given neutralizing anti-IL-10 antibody at the time of antigenic challenge, the duration of CHS was prolonged well beyond the natural course of the response. Finally, we demonstrate that rIL-10, when injected into the skin before antigenic challenge, prevented the elicitation of CHS in previously sensitized mice. Taken together, our data show an important role for IL-10 in the natural regulation of CHS responses in vivo.

Animals↗

PubMed1994

Detection of cellular adhesion molecules in inflamed human corneas.

PURPOSE: The expression of cellular adhesion molecules in 31 penetrating keratoplasty specimens from a broad range of corneal inflammatory diseases was studied using monoclonal antibodies and an immunoperoxidase technique. METHODS: Corneas were divided into noninflamed, mild to moderately inflamed, and severely inflamed groups based on histologic findings. The panel of adhesion molecules studied included HLA-ABC, HLA-DR, CD3, LFA-1, MAC-1, ICAM-1, PECAM-1, VCAM-1, and E-selectin-1. RESULTS: The adhesion molecules ICAM-1, HLA-DR, PECAM-1, CD3, VCAM-1, LFA-1, and MAC-1 were selectively expressed in areas of corneal inflammation. In general, HLA-DR and intercellular adhesion molecule ICAM-1 were co-expressed in similar regions. PECAM-1 was restricted to zones of marked inflammation and vascularization. E-selectin-1 was detected only in the stroma of a graft melt in a patient with active ocular cicatricial pemphigoid, and may reflect a primary regulatory dysfunction in this disorder. The ICAM-1 ligand was, in general, more diffusely distributed than its receptor LFA-1, a beta-2 integrin found on leukocyte cell membranes. The localization of the integrin MAC-1, present on macrophages, neutrophils, and some lymphocytes, did not always parallel the staining pattern of ICAM-1, suggesting promiscuity in its binding to other ligands besides ICAM-1. CONCLUSIONS: Adhesion molecules are detected readily at sites of corneal inflammation and may play a critical role in facilitating the recruitment of immune regulatory cells to these areas. Future efforts to block or modulate the expression of intercellular adhesion molecules may provide new therapeutic options in the treatment of corneal inflammatory diseases.

Adult↗

PubMed1994

The immune response and the eye: a role for TNF alpha in anterior chamber-associated immune deviation.

PURPOSE: Interleukin-1 and tumor necrosis factor (TNF) alpha are proinflammatory cytokines and crucial mediators in many aspects of immunity. In this study, their role in anterior chamber-associated immune deviation (ACAID) was investigated. METHODS: The role of these cytokines was examined by the use of neutralizing antibodies to TNF and interleukin (IL)-1 alpha, IL-1 beta, and IL-1 receptor. These reagents were co-injected with antigen into the anterior chamber and the effect on ACAID assessed. In addition, reverse transcriptase polymerase chain reaction (RT-PCR) was performed on eyes injected with TNP-spleen or bovine serum albumin to determine the levels of TNF alpha mRNA induced. RESULTS: Neutralizing antibody to TNF, when injected with TNP-spleen cells into the anterior chamber, blocked ACAID to the TNP hapten. Antibodies to IL-1 alpha, IL-1 beta, and IL-1 receptors either alone or in combination did not block the establishment of ACAID: Studies with reverse transcriptase polymerase chain reaction (Rt-PCR) confirmed that early (within 2 hours) after anterior chamber injection of TNP-cells, messenger RNA levels for TNF alpha were dramatically increased. The induction of ACAID to bovine serum albumin also required the production of TNF alpha. Further studies showed that the production of blood borne "ACAID-inducing" signals after anterior chamber injection of bovine serum albumin or TNP-spleen were dependent on TNF. CONCLUSIONS: TNF alpha plays a crucial role in ACAID: Induction of TNF alpha within the eye may be an important event in the complex series of events that induce ACAID and possibly maintain immunologic privilege.

Animals↗

PubMed1994

The immune response and the eye: the ACAID inducing signal is dependent on the nature of the antigen.

PURPOSE: To examine conditions that determine the nature of the blood-borne, ACAID-inducing signal produced after intracameral injection of antigen. METHODS: Balb/c mice were splenectomized, rested, and injected in the anterior chamber with various antigens. Two days later the animals were bled, the plasma and white cells were isolated, and these fractions were transferred to naive mice (with spleens). Recipients were immunized subcutaneously within 2 to 7 days and delayed type hypersensitivity was assessed 10 to 14 days after immunization by challenge with the appropriate antigen. RESULTS: The antigens HSV-1, TNP-coupled cells, and P815 tumors cells induced a soluble ACAID-inducing signal found in the plasma portion of blood. The soluble protein antigens bovine serum albumin (BSA) and conalbumin induced a cell-associated signal. When T-cells were included with protein antigens, a soluble (not cellular) ACAID-inducing signal was induced. CONCLUSIONS: Particulate antigens, such as HSV-1 and P815, that elicit intraocular T-cell responses or antigens that contain T-cells (e.g., TNP cells) induce a soluble, ACAID-inducing signal. Soluble antigens (e.g., BSA and conalbumin) induce a cell-associated ACAID signal. Additionally, T-cells are capable of modulating the type of ACAID signal produced. These results show that two methods of delivering the ACAID signal exist that are dependent on the nature of the antigen and the presence of T-cells. The authors conclude that the eye shows great versatility in regulating potentially damaging immune responses.

Animals↗

PubMed1993

Antigen-independent processes in antigen-specific immunity. A role for alpha 4 integrin.

It has been proposed that the migration of immune T cells out of blood vessels through connective tissue to the site of antigenic challenge is facilitated by the interaction of VLA integrins on lymphocytes with endothelial cell adhesion molecules and matrix proteins. Indeed, we have recently demonstrated that peptides derived from sequences in fibronectin abrogate the T cell-mediated contact hypersensitivity (CHS) reactions in vivo. These peptides blocked the interaction of the integrins VLA-4 and VLA-5 with fibronectin (FN), and our results suggested that by preventing the interaction of T cell integrins with FN, we successfully prevented the migration of T cells to sites of antigenic challenge. To further explore the role of integrins in T cell migration, we have used an antibody (R1-2) specific for the alpha-chain of alpha 4 integrins. Our data show that this antibody stains more than 90% of CD3+ T cells, and this percentage does not change after the mice have been immunized with a contact sensitizer. We also show that this antibody blocks the interaction of cells with immobilized FN and vascular cell adhesion molecule-1 on activated endothelial cells. Although R1-2 identifies alpha 4 integrin on a large number of T cells, it does not discriminate between activated and resting forms of this integrin, because very few T cells from immune or nonimmune mice actually bind FN or activated endothelium. In vivo, antibody R1-2 effectively blocks Ag-specific CHS, but has little effect on the non-Ag-specific cells that localize to the site of antigenic challenge. The population of cells that adoptively transfer CHS exits with the population of cells that bind to FN or to activated endothelial cells. Our data demonstrate that a small number of Ag-specific T cells use alpha 4 integrin to enter sites of inflammation and mediate effector immune responses. Ag-independent accumulation of T cells near sites of inflammation does not appear to be mediated by alpha 4 integrin.

Animals↗

PubMed1993

The regulation by light of retinal necrosis and the immune response following anterior chamber inoculation of herpes simplex virus type-1.

Following anterior chamber injection of the KOS strain of herpes simplex virus type 1 into Balb/c mice a characteristic pathologic response occurs. When examined 10-14 days later there is intense anterior segment inflammation of the injected eye, but the retina is spared. In contrast, the contralateral eye undergoes intense and destructive retinitis with little or no involvement of the anterior segment. Coincident with these observations is the induction of ACAID (for anterior chamber associated immune deviation) which is characterized by a suppressed DTH response, normal antibody titers, and normal cytolytic T-cell responses to HSV antigens. Since we have recently demonstrated that ACAID does not take place in the absence of light (i.e., is light dependent), we have examined the effect of light on the HSV-retinitis model. When Balb/c mice are either dark-reared or dark-adapted prior to AC injection of HSV-1, contralateral retinitis is abolished. Concurrent with the abrogation of retinitis, is the elimination of ACAID to HSV-1 antigens. In addition, although contralateral retinitis and ACAID do not develop in dark-reared mice if they are placed in the light immediately following injection, both can be re-established in dark-reared animals following a 2 week period of re-adaptation to light. Our results demonstrate that the entrance of light into the eye is not only important for ACAID, but also for the development of contralateral HSV-induced retinitis.

Animals↗

PubMed1993

A potential pathophysiologic role for alpha 2 beta 1 integrin in human eye diseases involving vitreoretinal traction.

Cell-mediated contraction of tissues containing fibrillar collagens can lead to organ compromise and loss of function. The same process that is biologically advantageous during the contraction phase of wound healing can be subverted in diseases such as hepatic cirrhosis, pulmonary fibrosis, and scleroderma, although the cellular and molecular mechanism of matrix tissue contraction is difficult to study in such chronic diseases. However, certain human eye diseases that result in tractional detachment of the retina and loss of vision are characterized by acute cell-mediated contraction of collagenous tissue in the vitreous cavity. In this study, we demonstrate that human cells can contract vitreous, a complex biological gel containing type II collagen, in vitro. This cell-mediated contraction can be blocked by antibodies and peptides that antagonize the function of alpha 2 beta 1 integrin, and the potential for contraction can be conferred upon noncontracting cells by stable transfection of cells with alpha 2 cDNA. We also show that this contractile process, if focally resisted, can result in remodeling vitreous from a gel to a structure that resembles a planar membrane, and that substantial isometric forces can be measured across this tissue. We propose that in diseases such as proliferative diabetic retinopathy and proliferative vitreoretinopathy, alpha 2 beta 1 integrin-mediated contraction of the vitreous and tension at the site of vitreoretinal attachments contribute to the terminal event of tractional retinal detachment. By extension, we propose that alpha 2 beta 1 integrin is a centrally important molecule in human diseases characterized by remodeling and contraction of collagenous tissue (i.e., fibrocontractive diseases).

Antibodies↗

PubMed1992

The wavelength of light governing intraocular immune reactions.

Injection of antigen into the anterior chamber of the eye results in the induction of suppressed systemic cell-mediated responses as measured by delayed-type hypersensitivity or contact hypersensitivity (CHS). Previous studies from the author's laboratories have determined that this response is governed by exposure of the eye to visible light during the initial intraocular encounter between T cells and antigen. To more fully understand the role of light, as well as to begin to understand the molecular mediators involved, the authors chose to explore the properties of light governing the effect. Neutral density filter were used to demonstrate that the minimum amount of light required to induce suppression of CHS following anterior chamber injection of antigen is 1-2 lux (lumens/meter2). With narrow band filters, the wavelengths responsible for suppression were shown to be 500-510 nm. The results show that the effect of light extends beyond the hapten-derivatized spleen cell system to other antigens placed in the anterior chamber of the eye. Studies also show that the retina and the pineal gland, two light absorbing structures, may not be involved. The results in this report show that light of very restricted wavelengths controls intraocular immune reactions.

Animals↗

PubMed1991

Two integrin-binding peptides abrogate T cell-mediated immune responses in vivo.

Two VLA proteins (or beta 1 integrins; originally called very late activation antigens) that bind to distinct determinants on fibronectin (FN) are increased on activated immune or memory T cells. VLA-4 binds to the peptide sequence Gly-Pro-Glu-Ile-Leu-Asp-Val-Pro-Ser-Thr (GPEILDVPST in single-letter code) on the alternatively spliced CS-1 form of FN, whereas VLA-5 binds to an Arg-Gly-Asp sequence found on all forms of FN. It has been proposed that the migration of immune T cells out of blood vessels and through connective tissue to a site of antigenic challenge is facilitated by the interaction of such integrins with matrix protein molecules. We have examined directly the role of T-cell integrins in vivo by using the well-characterized, T-cell-mediated contact hypersensitivity (CHS) response to the hapten trinitrochlorobenzene (TNCB). We demonstrate that the cells that transfer CHS to TNCB adhere to FN in the presence of Ca2+/Mg2+, and T-cell populations depleted of FN-adherent cells do not transfer immunity. We further show that TNCB-immune T cells treated with the synthetic peptides GPEILDVPST or Gly-Arg-Gly-Asp-Ser-Pro (GRGDSP in single-letter code), ligands for VLA-4 and VLA-5, respectively, lose their ability to mediate this immune response in a murine model, whereas the control peptides Val-Ile-Pro-Asp-Leu-Thr-Glu-Ser-Pro-Gly and Gly-Arg-Gly-Glu-Ser-Pro have no effect. Neither GPEILDVPST nor GRGDSP significantly inhibited the proliferative response of TNCB-immune T cells in vitro. These data suggest that FN-binding integrins on T cells play a role in the localization of T cells to sites of antigenic challenge in tissue.

Amino Acid Sequence↗

PubMed1991

Inhibition of lymphocyte proliferation by resident ocular cells.

The mechanisms by which the eye maintains an immunosuppressive environment has been the subject of recent investigations. In this report we investigated the ability of resident ocular cells from the iris, choroid, and retina to inhibit lymphocyte responses in vitro. Our results demonstrate that single cell suspensions derived from iris and choroid to inhibit alloantigen induced lymphocyte proliferation. We show that this inhibition was mediated by soluble factors which are low (less than 10,000) and intermediate (10,000-30,000) molecular weight molecules. This capacity is limited to iris and choroid and is not demonstrable in cell preparations derived from the retina. We conclude from our studies that cells derived from iris and choroid are capable of regulating immune responses and suggest that these cells (or their soluble products) may play a role in the immunosuppressive environment of the eye.

Alkylating Agents↗

PubMed1989

The immune response and the eye. III. Anterior chamber-associated immune deviation can be adoptively transferred by serum.

After the anterior chamber (AC) injection of trinitrophenol-coupled (TNP) spleen cells, it is observed that systemic delayed-type hypersensitivity responses to TNP are inhibited by Ag-specific suppressor T cells. We recently reported that suppression is initiated by viable TNP-coupled T cells within the inoculum and upon further analysis we found that these cells have the surface phenotype of CD4+ Ts inducer cells. We report here that treatment of these TNP-T cells with cycloheximide or cytochalasin-B before to AC injection abolishes suppression, whereas treatment with 2000 rad radiation does not. This indicates that protein synthesis and secretion are required to initiate suppression but proliferation is not. Further, we demonstrate the adoptive transfer of suppression by serum of AC inoculated animals. Detection of the component in serum in adoptive transfer assays, however, requires removal of the spleen before AC injection. We establish that the material in serum is a Ts cell product (T suppressor-inducer factor) based on three criteria: it is Ag specific, genetically restricted, and reactive with a mAb that specifically identifies these molecules. These results suggest that the signal leaving the eye to induce suppression of delayed-type hypersensitivity is T cell derived and that molecules mediating immune regulation for this organ are made within the eye and transported via the serum to the spleen.

Animals↗

PubMed1989

An approach to the unification of suppressor T cell circuits: a simplified assay for the induction of suppression by T cell-derived, antigen-binding molecules (T-ABM).

A system is presented in which the in vitro response to sheep red blood cells (SRBC) can be regulated using antigenic determinants coupled to SRBC and T cell-derived antigen-binding molecules (T-ABM) directed against the coupled determinants. T suppressor-inducer factors (TsiF's) are composed of two molecules, one of which is a T-ABM and one which bears I-J determinants (I-J+ molecule). Using two purified T-ABM which have not previously been shown to have in vitro activity, we produced antigen-specific TsiF's which were capable of inducing the suppression of the anti-SRBC response. Suppression was found to require both the T-ABM and the I-J+ molecule, SRBC conjugated with the antigen for which the T-ABM was specific, and a population of Ly-2+ T cells in the culture. Two monoclonal TsiF (or TsF1) were demonstrated to induce suppression of the anti-SRBC response in this system, provided the relevant antigen was coupled to the SRBC in culture. The results are discussed in terms of the general functions of T-ABM in the immune system. This model will be useful in direct, experimental comparisons of the function of T-ABM and suppressor T cell factors under study in different systems and laboratories.

Animals↗