Immunomodulatory effect of Tylophora indica on Con A induced lymphoproliferation.

Our preliminary studies with tylophora alkaloids had shown that they inhibit cellular immune responses like contact sensitivity to dinitro-flurobenzene and delayed hypersensitivity to sheep red blood cells, in vivo. Investigations were hence carried out to determine the cellular targets of tylophora alkaloids in in vitro systems. Con A induced proliferation of splenocytes was used as a model system to study the effect of the alkaloids on cellular immune responses. The alkaloid mixture was found to inhibit proliferation of splenocytes at higher concentrations and augment the same at lower concentrations. Both macrophages and T cells were found to be vulnerable to tylophora alkaloids. The alkaloid mixture suppressed IL-2 production in Con A stimulated splenocytes at the inhibitory or higher concentrations and enhanced production at the lower concentrations. IL-1 production by activated macrophages on the contrary was doubled in the presence of inhibitory concentrations of tylophora. These studies indicate that tylophora alkaloids have a concentration dependent biphasic effect on Con A induced mitogenesis. At lower concentrations they augment Con A induced lymphoproliferation by enhancing IL-2 production. Inhibition of proliferation at higher concentrations of the alkaloid is due to inhibition of IL-2 production and activation of macrophages, which have a cytostatic effect.     

Immunomodulatory effect of Tylophora indica on Con A induced lymphoproliferation

Our preliminary studies with tylophora alkaloids had shown that they inhibit cellular immune responses like contact sensitivity to dinitro-flurobenzene and delayed hypersensitivity to sheep red blood cells, in vivo. Investigations were hence carried out to determine the cellular targets of tylophora alkaloids in in vitro systems. Con A induced proliferation of splenocytes was used as a model system to study the effect of the alkaloids on cellular immune responses. The alkaloid mixture was found to inhibit proliferation of splenocytes at higher concentrations and augment the same at lower concentrations. Both macrophages and T cells were found to be vulnerable to tylophora alkaloids. The alkaloid mixture suppressed IL-2 production in Con A stimulated splenocytes at the inhibitory or higher concentrations and enhanced production at the lower concentrations. IL-1 production by activated macrophages on the contrary was doubled in the presence of inhibitory concentrations of tylophora. These studies indicate that tylophora alkaloids have a concentration dependent biphasic effect on Con A induced mitogenesis. At lower concentrations they augment Con A induced lymphoproliferation by enhancing IL-2 production. Inhibition of proliferation at higher concentrations of the alkaloid is due to inhibition of IL-2 production and activation of macrophages, which have a cytostatic effect.     

Suppression of experimental autoimmune uveitis in mice by induction of anterior chamber-associated immune deviation with interphotoreceptor retinoid-binding protein.

Immunization with bovine interphotoreceptor retinoid-binding protein induces autoimmune uveitis in B10.A mice. We have examined whether this soluble retina-specific Ag can induce anterior chamber-associated immune deviation when injected into the anterior chamber (AC) of the eye, and whether this deviant immune response has any effect on uveitis is susceptible mice. The results of these experiments indicate that interphotoreceptor retinoid-binding protein (IRBP) injected intracamerally altered the subsequent immune response of B10.A mice such that a) they were not able to develop IRBP-specific delayed hypersensitivity, nor (b) were they able to express significant autoimmune uveitis following a uveitogenic regimen. Moreover, spleen cells from mice that received IRBP in the AC suppressed uveitis when adoptively transferred into naive recipients. The splenic suppressor cells were able to prevent autoimmune uveitis in recipient mice when administered after the uveitogenic regimen. Most important, IRBP-specific splenic cells from mice treated with IRBP in the AC when injected into mice with established uveitis caused an abrupt cessation of the intraocular inflammation. The ability of intracamerally-injected soluble Ag to induce suppressor T cells that act on the efferent limb of the immune response suggests that the anterior-chamber-associated immune deviation phenomenon may have physiologic relevance in terms of preservation of the integrity of ocular tissue and renders this approach particularly suitable for treating already established experimental autoimmune diseases of this type. These results are discussed in terms of other methods that have been devised experimentally to suppress and prevent autoimmune uveitis and encephalomyelitis.     

甲状腺激素对小鼠免疫功能的调节作用

正常昆明种成年小鼠每天给予一定量的甲状腺激素可使其抗体生成能力、淋巴细胞转化能力、迟发型超敏反应和巨噬细胞的吞噬功能明显增强,外周血成熟 T 细胞数量亦明显增加。而每天给予抗甲状腺药物则使其抗体生成能力、淋巴细胞转化能力和迟发型超敏反应明显降低。切除甲状腺亦使抗体生成能力下降。这些结果提示甲状腺激素参与免疫功能的生理性调节。     

The role of suppressor factors in the regulation of immune responses by ultraviolet radiation-induced suppressor T lymphocytes. I. Activity of suppressor cell culture supernatants

The purpose of this study was to determine whether soluble suppressor factors are involved in the regulation of immune responses by ultraviolet radiation-induced suppressor T lymphocytes (UV Ts). The UV Ts were induced by applying contact allergens to the ventral, unirradiated skin of mice that had been exposed 5 days earlier to UVB radiation. Supernatants from cultures that contained a mixture of UV Ts, normal responder lymphocytes, and hapten-modified stimulator cells were injected iv into normal recipients at the time of sensitization; they inhibited the induction of contact hypersensitivity (CHS) in vivo in an hapten-specific manner. The supernatants similarly suppressed the generation of specific cytotoxic T lymphocytes (CTL) in vitro. Moreover, supernatants from cultures that contained either UV Ts alone or UV Ts in combination with either the responder or the stimulator cells failed to suppress the CHS and CTL responses. These results suggest that hapten-specific inhibitory factors may participate in the regulation of immune responses by suppressor cells generated by epicutaneous sensitization of UV-irradiated mice.     

Delayed hypersensitivity in mast-cell-deficient mice

The ability of mast cell-deficient Wf/Wf and W/Wv mice to produced delayed hypersensitivity responses was examined. The W/Wv mice did not have detectable mast cells and could not produce IgE-mediated passive cutaneous anaphylaxis. Mice of both genotypes produced large delayed hypersensitivity responses to the contact sensitizers oxazolone and picryl chloride. The responses were indistinguishable from responses of control mice when challenged with optimal or suboptimal doses of antigen. Delayed hypersensitivity could be transferred into Wf/Wf mice by an antigen-specific T cell line, and the proliferative responses in the lymph nodes of these mice after, painting with sensitizer, were normal.     

CCR7 coordinates the primary immune response by establishing functional microenvironments in secondary lymphoid organs.

The proper function of immune surveillance requires well-coordinated mechanisms in order to guide the patrolling immune cells through peripheral tissues and into secondary lymphoid organs. Analyzing gene-targeted mice, we identified the chemokine receptor CCR7 as an important organizer of the primary immune response. CCR7-deficient mice show severely delayed kinetics regarding the antibody response and lack contact sensitivity and delayed type hypersensitivity reactions. Due to the impaired migration of lymphocytes, these animals reveal profound morphological alterations in all secondary lymphoid organs. Upon activation, mature skin dendritic cells fail to migrate into the draining lymph nodes. Thus, in order to bring together lymphocytes and dendritic cells to form the characteristic microarchitecture of secondary lymphoid organs, CCR7 is required to rapidly initiate an adoptive immune response.     

Suppressor cells in contact sensitivity. Effect on T cells helping antibody production to picryl chloride.

T cells from mice injected with picryl sulfonic acid have previously been shown to suppress the effector and possibly other phases of contact hypersensitivity reactions to picryl chloride. In this report we examine their effect on T cells helping the early direct anti-TNP plaque-forming cell response of mice painted with picryl chloride. They did not directly inhibit the activity of the helper cells but did inhibit the ability of mice to generate helper cells after skin painting. The suppressor cells were T cells as tested by passage through nylon wool columns and sensitivity to anti-θ serum. Viable syngeneic cells were required for suppression and their effect was specific. The suppressor cells could not be generated in adult thymectomized mice but could be produced in mice treated with high doses (200 mg/kg) of cyclophosphamide. These properties are distinct from those of suppressor T cells produced following immunization with picryl chloride but are the same as those of other suppressor cells induced by PSA which inhibit contact hypersensitivity.     

The effect of the antigen-induced splenic suppressor factor on the immune response to different antigens

Quick-frozen spleen of mice immunized with sheep red blood cells was homogenized and centrifuged. Supernatant was used as a source of suppressor factor (SF). It was shown that SF inhibited antibody immune response to thymus-dependent antigens and delayed hypersensitivity reaction. SF did not inhibit antibody formation to thymus-independent antigen. SF activity disappeared after its treatment with anti-Ig immunosorbent.     

Induction of apoptosis in a human erythroleukemic cell line K562 by Tylophora alkaloids involves release of cytochrome c and activation of caspase 3

Tylophora alkaloids are plant products known for their antiasthamatic and antiproliferative activities. The underlying cellular changes resulting from inhibition of proliferation were investigated. Tylophora alkaloids induced apoptosis in K562 cells with characteristic apoptotic features like nuclear condensation, apoptotic body formation, flipping of membrane phosphatidylserine, activation of caspase 3 and release of mitochondrial cytochrome c. These studies suggest that the Tylophora alkaloids, in addition to their antiproliferative effects also induce apoptosis in erythroleukemic cells. These observations imply that Tylophora alkaloids could be useful molecules for their antiproliferative activity and for induction of apoptosis in tumor cells.     

Oviposition-stimulatory activity of phenanthroindolizidine alkaloids of host-plant origin to a danaid butterfly, Ideopsis similis

Oviposition response of Ideopsis similis (L.) (Lepidoptera: Danaidae) was examined for 12 phenanthroindolizidine alkaloids present in its host plant, Tylophora tanakae (Maxim.) (Asclepiadaceae). At least five alkaloids, i.e. (+)‐isotylocrebrine (3,4,6,7‐tetramethoxyphenanthroindolizidine; l ), (+)‐3‐demethyliso‐ tylocrebrine ( 3 ), (+)‐isotylocrebrine N‐oxide ( 5 ), (+)‐6‐demethyltylocrebrine ( 8 ) and (–)‐7‐demethyltylophorine ( 10 ), were found to individually stimulate oviposition by females. Of these, compounds 1, 3 and 10 were regarded as key components most responsible for host recognition or preference. However, female egg‐laying was much higher in response to a mixture of the five alkaloids. In two‐choice bioassays, more eggs were deposited on samples comprising the five alkaloids than on samples consisting of a single alkaloid. This suggests strongly that host selection by the butterfly is mediated by the synergistic action of several phenanthroindolizidine alkaloids present in the host plant.     

Relation of the immunosuppressivity of virulent Shigella to the structure of O antigen

The capacity of filtrates of virulent Shigella cultures (VSC) and their different fractions to render avirulent strains, injected intraperitoneally into mice simultaneously with these filtrates, capable of suppressing immune response (delayed hypersensitivity) has been studied. Among the fractions of VSC filtrates, the lipoid fraction soluble in the mixture of ethanol and ether has proved to be active. Active factors can be extracted from VSC filtrates by means of immunosorbents obtained from antibodies of pertinent specificity. VSC filtrates are completely inactivated by treatment with phenol and trichloroacetic acid. These data suggest that the immunosuppressive factors of shigellae, responsible for their capacity to suppress immunological memory, are incorporated into the O-antigen of these bacteria.     

The role of suppressor factors in the regulation of immune responses by ultraviolet radiation-induced suppressor T lymphocytes. II. Activity of suppressor cell culture sonicates

The purpose of this study was to determine whether multiple types of suppressor factors play a role in the regulation of immune responses by ultraviolet radiation-induced suppressor T lymphocytes (UV Ts). The UV Ts were induced by applying contact allergens to the ventral, unirradiated skin of mice exposed 5 days earlier to UVB radiation. Previous studies indicated that supernatants from cultures containing UV Ts, normal lymphocytes, and hapten-modified cells suppressed contact hypersensitivity (CHS) in vivo and cytotoxic T lymphocyte (CTL) generation in vitro in a hapten-specific manner. In this report, cell-free lysates from sonically disrupted UV Ts were examined for their ability to suppress these responses. When lysates were injected into normal animals at the time of sensitization, they inhibited CHS in a hapten-nonspecific manner. In addition, the lysates suppressed not only the induction but also the elicitation of CHS, and they suppressed the generation of CTL. Lysates prepared from spleen cells obtained from non-UV-irradiated mice or UV-irradiated, unsensitized mice failed to inhibit either response. Moreover, in contrast to the lysates, the hapten-specific UV Ts culture supernatants inhibited the induction but not the elicitation of CHS. These results suggest that both hapten-specific and nonspecific inhibitory factors may participate in the regulation of immune responses by UV Ts.     

A possible explanation for the synergism between mixed T- and B- cell populations in mice adoptively immunized with Ancylostoma caninum

Ancylostoma caninum--mouse model was employed to study the cellular cooperation in the adoptive immune response. The syngeneic recipient mice were intraperitoneally injected once or twice with mixtures of thymus and bone marrow cells from infected (with 500 or 2000 larvae) and uninfected donors. The experimental recipients expelled and/or destroyed the challenge larval burden more readily and at a greater rate than the controls with unsensitized cells. The cooperation between sensitized thymus and bone marrow cells was, thus, found to be exposed in a better manifestation of adoptive immune response than either of these two alone. The cellular elements of delayed hypersensitivity after combining with the antibodies of humoral system could elicit a much better response in these recipients.     

The development of Staphylococcus-induced delayed hypersensitivity and antigen-non specific immunosuppression in a state of rest and during physical loading of varying intensities

Injection of live staphylococcal culture into mice induces the development of delayed hypersensitivity (DH) to microbial cells and suppresses the development of humoral immune response (HIR) to sheep red blood cells (SRBC). Physical loading of low intensity normalizes staphylococcus-suppressed HIR to SRBC, but produces no effect on staphylococcus-induced DH. Highly intensive physical loading suppresses the development of DH and enhances the suppressive effect of staphylococci on SRBC-induced HIR. The infection of animals with staphylococci induces the secretion of immunosuppressive factors by spleen cells. Physical loading of low intensity does not suppress the staphylococcus-induced secretion of suppressive factors by spleen cells, but induces the secretion of helper factors by these cells. Highly intensive physical loading enhances the secretion of immunosuppressive factors by spleen cells after infection with staphylococci.     

Mechanisms involved in the antibody-mediated suppression of tuberculin-type delayed hypersensitivity: II. The sensitivity of tolerance induction to cyclophosphamide pretreatment and splenectomy,and the demonstration of active suppression

The induction of tuberculin-type delayed hypersensitivity, as measured by skin test, can be specifically inhibited by administration of antibody during sensitization. The cellular mechanisms involved in this tolerance were investigated in CAP₁ mice, using chicken conalbumin as antigen. Tolerance was prevented when mice were treated with Cyclophosphamide 2 days before sensitization and suppression. However, it was not affected by splenectomy 7 or 21 days before sensitization. This tolerance could be transferred to normal CAF₁ mice with spleen cells, but not with thymocytes, when taken from donor mice 21 to 28 days after sensitization and tolerance induction. Production of these cells in the donors required both antibody and antigen. The cells responsible for the transfer were B cells, as shown by their sensitivity to rabbit anti-mouse-immunoglobulin serum and complement. In addition to B cells, serum from tolerant mice also could transfer suppression at 21 to 28 days. We conclude that sensitizing mice, and treating them with specific immunosuppressive antiserum, induces the recipients to make suppressor B cells and suppressive humoral factors, which are involved in arresting the induction of tuberculin-type delayed hypersensitivity.     

Inhibition of delayed hypersensitivity reactions in mice by colchicine. I. Mechanism of inhibition of contact sensitivity in vivo

Colchicine has been recently shown to inhibit delayed hypersensitivity reactions (DHR). In the present study we investigated the effects of colchicine on contact sensitivity (CS) to dinitrofluorobenzene. Colchicine, at a dosage level of 15 micrograms/mouse, inhibited the elicitation of the contact response only when given on the day of ear challenge. Administration of the drug during the induction phase did not have any effect on the CS reaction. By using adoptive transfer experiments, we could demonstrate that CS was suppressed only when colchicine was given to the recipient mice, while treating the donors of immune lymph node cells (I-LNC) did not affect their ability to transfer a significant DHR. These findings were observed also when I-LNC were directly injected into the ears, a result which indicated that there was no effect of the drug on the ability of effector cells to migrate to the site of antigen challenge. Neither was there any effect on the distribution of T cell subsets in peripheral lymph nodes. The proliferative response of LNC to antigenic or mitogenic stimulation in vivo or in vitro was also not affected by colchicine pretreatment. These findings raise major questions about the mechanism of action of colchicine in vivo and suggest that more experimentation is required to probe the mechanism of colchicine-induced suppression of DHR.     

Immune studies in the depigmenting C57BL/Ler-vit/vit mice. An apparent isolated loss of contact hypersensitivity

Vitiligo is a human disorder which destroys pigment cells in the skin, ears, eyes, and meningeal tissues and has often been associated with a variety of autoimmune disorders. The C57BL/Ler-vit/vit mouse is a mutant strain that exhibits a loss of epidermal pigment cells and a selective cell-mediated immune deficiency to epicutaneous-administered allergens. This observation is consistent with that observed in humans with vitiligo, who also exhibit loss of contact hypersensitivity (CHS), that appears to be associated with loss of pigment cells from the epidermis. Other cellular immune parameters such as delayed type hypersensitivity and antibody generation to both particulate and soluble Ag are normal or even hyperimmune in the vit/vit mice compared with congenic C57BL/6 controls. Cyclophosphamide treatment could reconstitute CHS responsiveness of the vit/vit mice to the allergen dinitrofluorobenzene. Further, this loss of CHS responsiveness to dinitrofluorobenzene could be restored with skin transplants from normal pigmented C57BL/6 mice to vit/vit mice. Normal C57BL/6 mice bearing white skin grafts from vit/vit mice did not contact sensitize. We suggest that this vit/vit mouse strain may serve as an excellent system to investigate various aspects of other contact hypersensitivity reactions as well as vitiligo.     

Catecholamines inhibit the antigen-presenting capability of epidermal Langerhans cells

The sympathetic nervous system modulates immune function at a number of levels. Within the epidermis, APCs (Langerhans cells (LC)) are frequently anatomically associated with peripheral nerves. Furthermore, some neuropeptides have been shown to regulate LC Ag-presenting function. We explored the expression of adrenergic receptors (AR) in murine LC and assessed their functional role on Ag presentation and modulation of cutaneous immune responses. Both purified LC and the LC-like cell lines XS52-4D and XS106 expressed mRNA for the ARs alpha(1A) and beta(2). XS106 cells and purified LC also expressed beta(1)-AR mRNA. Treatment of murine epidermal cell preparations with epinephrine (EPI) or norepinephrine inhibited Ag presentation in vitro. Furthermore, pretreatment of epidermal cells with EPI or norepinephrine in vitro suppressed the ability of these cells to present Ag for elicitation of delayed-type hypersensitivity in previously immunized mice. This effect was blocked by use of the beta(2)-adrenergic antagonist ICI 118,551 but not by the alpha-antagonist phentolamine. Local intradermal injection of EPI inhibited the induction of contact hypersensitivity to epicutaneously administered haptens. Surprisingly, injection of EPI at a distant site also suppressed induction of contact hypersensitivity. Thus, catecholamines may have both local and systemic effects. We conclude that specific ARs are expressed on LC and that signaling through these receptors can decrease epidermal immune reactions.     

In vivo effects of cyclosporine on influenza A virus-infected mice

Cyclosporine (cyclosporin A, CsA) administered to mice substantially affects their immune response to an influenza A virus infection. If treated with CsA for 21 days, the mouse lungs contain high titers of virus which are cleared more slowly than in controls. Indicators of pathological damage--lung weight, extent of consolidation, fine morphology, and the extent of infiltration of dividing cells into the lung--showed that administration of CsA greatly decreased the level of inflammation. The production of hemagglutination-inhibiting (HI) antibody was delayed but reached almost control levels and NK cell activity in the lung was also comparable to control levels. In contrast, a delayed-type hypersensitivity (DTH) response to the virus could not be elicited in the CsA-treated, infected mice at 6 or 12 days after infection. Cytotoxic-T-cell (Tc-cell) activity was present in the lungs of such mice though its appearance was delayed and the activity recovered was less than that of the control infected mice. If administered with a dose of virus lethal for normal mice. CSA-treated mice survived, probably due to the greatly reduced level of immunopathological damage in the infected lung.