Analysis of the T suppressor cell circuit which regulates contact sensitivity in mice infected with the virus of Newcastle disease.

The interaction between the virus of Newcastle disease (NDV) and the different cellular elements involved in the T suppressor cell circuit which regulates the expression phase of contact sensitivity has been investigated. NDV does not interfere with the production of the antigen-specific T suppressor factor (TsF) but inhibits its binding to T acceptor cells (Tacc). This cell when armed with TsF and exposed to the antigen corresponding to TsF releases a non-specific inhibitor of the transfer of contact sensitivity. More detailed analysis of the effect of NDV on the Tacc system showed that not only Tacc activity is impaired by NDV, but also the ability of antigen presenting cells (APC) to trigger Tacc armed with TsF is inhibited. The impairment of APC activity by NDV has been also investigated using another system, such as the induction of contact sensitivity by footpad cell transfer. The possibility that a virus-induced membrane modification might be responsible for the effect of NDV on the regulation of contact sensitivity is discussed.     

The role of I-J in the suppressor T-cell circuit which influences the effector stage of contact sensitivity: antigen together with syngeneic I-J region determinants induces and activates T suppressor cells

One of the T suppressor circuits induced by picrylsulphonic acid includes the T suppressor cell (Ts-eff) which acts at the efferent stage of the contact sensitivity reaction and produces antigen-specific T suppressor factor (TsF). This factor does not act directly but arms a T acceptor cell (Tacc). This Tacc liberates a non-specific inhibitor when it is armed with TsF and then exposed to picrylated cells sharing the I-J genotype of the source of the TsF. This paper investigates the role of I-J region gene products in this T suppressor circuit. Two approaches were used. Syngeneic CBA (H-2k) lymphocytes were separated into I-J+ and I-J- cells by treatment with anti-I-Jk serum followed by panning on anti-immunoglobulin plates. The cells were then picrylated and used as a source of antigen. Alternatively, B10.A congeneic mice syngeneic (5R) or allogeneic (3R) with CBA at the I-J locus were picrylated and used similarly. The main findings were as follows. (i) The intravenous injection of picrylated I-J+ spleen cells but not a similar number of I-J- cells induced Ts-eff which blocked the transfer of contact sensitivity. Picrylated unseparated cells syngeneic, but not allogeneic, at the I-J locus were also effective. (ii) It is known that the lymphocytes of mice injected wit picrylsulphonic acid and then re-exposed to antigen by painting with picryl chloride liberate TsF in vitro. The re-exposure to antigen can be replaced by the intravenous injection of picrylated I-J+ cells or by cells syngeneic at the I-J locus the day before harvesting the spleen cells. (iii) The release of non-specific inhibitor by Tacc armed with TsF requires exposure to picrylated I-J+ cells or cells syngeneic at the I-J locus. The requirement for antigen on a cell bearing syngeneic I-J suggests that antigen together with I-J is an activation signal in this T-cell circuit. The simplest explanation is that the receptor of the pristine Ts and of the mature Ts-eff is similar to T suppressor factor.     

Cell-cell interaction responsible for the induction of first order suppressor T cells in hapten-specific contact sensitivity reactions

C3H/He mice were found to be low responders in the contact sensitivity response to ABA. Intravenous injection of ABA-coupled syngeneic spleen cells induced hapten-specific Ts in C3H/He mice. These cells were Ts1 because they acted on the inductive phase of the contact sensitivity. They could suppress the contact sensitivity in H-2-compatible CBA mice which were known to be high responders to ABA. Using in vivo and in vitro systems for the induction of Ts, it was shown that I-A-I-J+Thy-1- adherent cells were necessary as APC for the induction of Ts1.     

Nonspecific macrophage suppressor factor: its role in the inhibition of contact sensitivity to picryl chloride by specific T suppressor factor.

Anti-picryl T suppressor factor was produced by culturing lymphoid cells from mice which were first injected with picryl sulfonic acid and then painted with picryl chloride. The supernatant was harvested at 48 h. Macrophage suppressor factor was produced by incubating peritoneal exudate cells (PEC) in T suppressor factor, washing and then adding antigen and taking the supernatant after incubation for 1 h. Immune cells incubated in the supernatant lost the ability to transfer contact sensitivity. The supernatant (macrophage suppressor factor) was nonspecific and inhibited the passive transfer of contact sensitivity to picryl chloride and oxazolone to a similar extent. Macrophage suppressor factor was only produced when PEC were incubated in anti-picryl T suppressor factor and then exposed to picrylated antigen. Syngeneic thymocytes picrylated in vitro were the best source of antigen. Allogeneic thymocytes and regional lymph node cells picrylated in vivo by painting with picryl chloride were less effective. Picrylated mouse red blood cells and picrylated mouse gamma globulin were least effective. Macrophage suppressor factor differed from T suppressor factor in several ways. It was nonspecific, its molecular weight was lower (10000–20000 daltons), and it failed to bind to PEC. It also failed to bind to immune cells at 0°C. Although macrophage suppressor factor inhibited passive transfer when the mice were tested immediately afterwards (Chase-Landsteiner transfer), it did not affect passive transfer when testing was delayed for a week. It is proposed that macrophage suppressor factor amplifies the effect of T suppressor factor.     

T cell suppression of contact sensitivity in the mouse. II. The role of soluble suppressor factor and its interaction with macrophages

Contact sensitivity in the mouse is assessed by the increase of ear thickness 24 hours after challenge with antigen and can be passively transferred by T cells in the lymph nodes and spleen of immunized mice. The lymph node cells of mice pretreated with picrylsulfonic acid specifically depress the passive transfer of contact sensitivity to picryl chloride by immune cells. “Suppressor” lymph node cells from mice injected with picrylsulfonic acid (?6 days) and painted with picryl chloride (-1 day) were incubated in vitro for 48 hours. Immune lymph node cells incubated in these supernatants have reduced ability to transfer contact sensitivity. This suppression is specific and passive transfer of contact sensitivity to 4-ethoxymethylene-2-phenyloxazolone is unaffected by incubation of immune cells in supernatant. Control supernatants from the cells of mice which did not receive picrylsulfonic acid or were not painted shortly before harvesting were inactive. The suppressor activity is absorbed by peritoneal exudate cells and these then acquire the ability to suppress passive transfer-“arming for suppression”. Normal and immune lymph node cells, and spleen cells do not become inhibitory under similar conditions. The suppressor activity of suppressor supernatants (which contain 10 % fetal calf serum) withstands freeze drying, heating at 56 °C and trypsin. Its production is T dependent and is abolished by treatment with anti-Θ serum and complement. The hypothesis is put forward that the active factor in suppressor supernatants is a specific T cell product either free or combined with antigen.     

Depression of contact sensitivity by enhancement of suppressor cell activity in Pseudomonas aeruginosa-injected mice.

Heat-killed Pseudomonas aeruginosa depresses contact sensitivity to oxazolone in C56BL/6 mice. The draining lymph nodes and spleens of mice exhibiting an impaired reactivity to oxazolone contain a cell population capable of depressing the response to oxazolone of recipients sensitized immediately before cell transfer. The suppressive activity of these cells appears to be antigen specific, since they do not affect the response to picryl chloride and because they do not arise in P. aeruginosa-injected but not oxazolone-sensitized mice. These suppressor cells occur in the draining lymph nodes and spleen at 3 and 4 days after sensitization, respectively, and have precursors sensitive to cyclophosphamide. It is concluded that P. aeruginosa depresses contact sensitivity to oxazolone by enhancing the suppressor cell activity of the regulatory cells which arise during conventional sensitization.     

Pseudomonas aeruginosa infection depresses contact sensitivity to oxazolone by enhancing suppressor cell activity

The depression of contact sensitivity to oxazolone in mice infected withPseudomonas aeruginosa was studied. In oxazolone-sensitized mice,P. aeruginosa infection affects cell proliferation in the lymph nodes draining the site of sensitization. This impaired cell proliferation does not seem to be due to an altered lymphocyte reactivity, since lymph node and spleen cells from infected animals show a normal mitotic responsiveness to both T and B cell mitogens. In addition, the draining lymph nodes and spleens of mice exhibiting a depressed response to oxazolone contain a cell population able actively to suppress the response to the same antigen of syngeneic recipients sensitized immediately before the cell transfer. These suppressor cells require antigenic stimulation and appear to act on the induction phase of contact sensitivity.     

Tolerance to experimental contact sensitivity induced by T cell vaccination

It was shown previously that experimental autoimmune diseases could be prevented or treated specifically by administering suitably attenuated autoimmune T lymphocytes to animals, a process termed T cell vaccination (Cohen, I. R., Sci. American 1988. 256: 52). We now report that T cell vaccination is an effective way of inducing tolerance to contact sensitivity to simple chemical haptens. Vaccines were prepared from populations of lymph node cells from specifically sensitized mice by activating the T cells with the T cell mitogen concanavalin A and then treating the T cell blasts with glutaraldehyde. The vaccinated mice showed decreased delayed sensitivity responses to the specific sensitizing antigen and developed significant delayed sensitivity responses to the T cells of the same specificity as those used for vaccination. Thus, T cell vaccination against contact sensitivity reactions appears to function similarly to T cell vaccination against autoimmune disease.     

Equivalence of conventional anti-picryl T suppressor factor in the contact sensitivity system and monoclonal anti-NP TsF3: their final non-specific effect via the T acceptor cell.

There is considerable confusion over whether the antigen-specific T suppressor factors (TsF) described by different authors are indeed equivalent. This paper investigates whether monoclonal TsF3, obtained from hybridomas derived from mice injected subcutaneously with NP derived spleen cells, is functionally equivalent to the conventional T suppressor factor, produced by mice injected intravenously with chemically reactive, water soluble haptene (picrylsulphonic acid and oxazolone thioglycolic acid). Comparison of monoclonal anti-NP TsF3 with conventional anti-picryl and anti-oxazolone T suppressor factor showed that both armed the non-specific T acceptor cell (Tacc) which was sensitive to cyclophosphamide and adult thymectomy. Moreover, non-specific inhibitor (nsINH) of the transfer of contact sensitivity was released when antigen, together with major histocompatibility complex products (MHC), reacted with conventional or monoclonal TsF on the surface of the non-specific T acceptor cell. The interaction of monoclonal TsF3 with antigen, which led to the release of NsINH, required the presence of MHC and was I-J restricted. However, there was no Igh-1 restriction. The equivalence of conventional anti-picryl and anti-oxazolone TsF has been demonstrated by arming the Tacc with a mixture of these two suppressor factors, and then triggering the release of nsINH with the mixed haptene 'picryl-oxazolone-lysine' which crosslinks separate molecules of TsF. A similar equivalence of conventional anti-oxazolone TsF and monoclonal anti-NP TsF3 was demonstrated using the mixed hapten 'NP-oxazolone-lysine' to trigger the release of nsINH. It was concluded that monoclonal TsF3 and conventional TsF were equivalent, and that both had an indirect mode of action through the non-specific T acceptor cell which led to the production of non-specific inhibitor.     

T suppressor afferent cells which regulate contact sensitivity to picryl chloride act across genetic barrier

This paper investigates the requirement for genetic restriction in the action of T suppressor afferent cells (Ts-aff) which regulate the induction phase of contact sensitivity to picryl chloride. The results here reported show that Ts-aff which inhibit both the induction of contact sensitivity and DNA synthesis in the draining lymph nodes of sensitized mice, act across both H-2 and Igh genetic barrier and constitute new evidence which discriminates between two T suppressor cell populations in contact sensitivity.     

Functional suppressor T cell activity in Crohn's disease and the effects of sulphasalazine.

Suppressor T cell activity was measured in 18 patients with Crohn's disease and 20 controls, using two different functional assays. The effects of sulphasalazine and its metabolites on in vitro suppressor cell activity were also studied. The activity of a Con A-induced suppressor cell system in patients with Crohn's disease did not differ from that of controls, suggesting that the previously reported abnormalities are a secondary phenomenon. Furthermore, the activity of a non-induced suppressor T cell system was also normal in these patients. There was no evidence either in vivo or in vitro to suggest that sulphasalazine exerts its beneficial action by an effect on this aspect of immunoregulation.     

染料木黄酮抑制小鼠变应性接触性皮炎的实验研究

目的： 探讨染料木黄酮(Gen)对小鼠变应性接触性皮炎(ACD)的抑制作用。 方法： 建立二硝基氟苯(DNFB)诱发的小鼠ACD模型，观测不同剂量Gen对小鼠耳廓肿胀程度、鼠耳皮肤组织病理变化、体重及胸腺指数、脾指数的影响。 结果： 各剂量Gen组均能明显抑制DNFB诱发的小鼠耳廓肿胀，抑制炎症细胞浸润，降低胸腺指数，且不影响小鼠体重增长。低剂量Gen组增加脾指数，高剂量Gen组降低脾指数。 结论： Gen对DNFB诱发的小鼠ACD有明显抑制作用。     

Central and peripheral action of suppressor cells in contact sensitivity in the guinea-pig.

Suppressor cells were demonstrated in the spleen of guinea-pigs made specifically unresponsive to dinitrofluorobenzene (DNFB) with dinitrobenzene sulphonic acid (DNBSO3). Transfusion of these cells at the same time as sensitization with DNFB, produced a significant reduction in the immunoblasts proliferating in the draining lymph node 4 days later. Transfusion on the day of skin testing produced no greater suppression of skin reactivity than cells taken from animals made hypo-reactive to DNFB by contact with dinitrothiocyanate benzene (DNTB). It is concluded that there are at least two sites that suppressor cells can act. In the case of total unresponsiveness induced by DNBSO3, action is both central and in the periphery. In the case of hyporeactivity induced by DNTB, in which there is no defect in proliferation of T cells in response to antigen, the action of these cells is confined to the periphery. results of spleen weight studies suggest that suppressor cells homing in the spleen respond by proliferation to epicutaneously applied DNFB.     

Effect of interferon-gamma on the abnormality of T cell activation in NZB mice

It is known that New Zealand black (NZB) mice have a defect in the autoantigen recognition mechanism by T cells. The present study was carried out to examine whether the defect could be improved by normalizing the self Ia molecule expression on thymic reticuloepithelial cells (TRC) by using interferon-gamma (IFN-gamma). Syngeneic mixed lymphocyte reaction (SMLR) was used as an indicator of the mechanism of autoantigen recognition. In the reaction, T cells separated from the thymus were used as responders, and machrophages separated from the spleen were used as stimulators. When the responders were cultured with TRC, in which self Ia molecule expressions had been enhanced by IFN-gamma, for activation, the low level of SMLR in NZB mice was elevated close to the normal level. It was suggested, therefore, that IFN-gamma could normalize the defective autoantigen expression on TRC in NZB mice and improve the abnormal T cell activation against autoantigens.     

Kinetics of the relation between suppressor and effector mechanisms in contact sensitivity in the guinea-pig

Cyclophosphamide (300 mg/kg) given before or up to 2 days after sensitization, induces increased contact skin reactions at 8 days. Reactions were suppressed with cyclophosphamide (CY) given between 3 and 5 days after sensitization; reactivity returned on day 10. CY, given on days 6 to 8, only suppressed reactions when skin tests were made 4 days later. This temporary depression of contact sensitivity corresponds with the maximal reduction of peripheral blood lymphocytes. CY given 1-2 days after DNFB produced decreased T-cell proliferation in local lymph nodes 4 days after sensitization. CY given 3 days after DNFB produced maximal T-cell suppression on 5 day nodes. Massive increase in T-cell proliferation in 5 day nodes occurred when CY was given on the day of sensitization or the day before. Thus CY given around sensitization acts mainly on suppressor cells whereas given later, the action is principally on the effector functions.     

Effect of the elimination of suppressor cells on the development of DNCB contact sensitivity in guinea-pig.

The effect of suppressor cells on the formation of effector cells was studied by comparing the development of DNCB contact sensitivity in cyclophosphamide-treated (suppressor cells eliminated) and non-treated (suppressor cells present) guinea-pigs. From experiments in four different models of generation of effector cells the following conclusions are drawn: (1) impulses activating the formation of effector cells also activate suppressor cells; (2) under conditions of conventional immunization, suppressor cells are activated later than effector cells; (3) elimination of suppressor cells results in an increase in the intensity and duration of specific skin reactions.     

Dominance of the BV17 element in nickel-specific human T cell receptors relates to severity of contact sensitivity

Hypersensitivity to nickel (Ni) represents the most common manifestation of contact allergy in humans. The role of metal-specific T cells in this disease is well established, but the molecular interactions involved in their activation are poorly understood. We examined the T cell receptor (TCR) repertoire in T cells activated with either NiSO₄ or NiSO₄-treated human serum albumin from six allergic patients. For the three most hyperreactive donors, we found a strong over-represention of the TCR BV17 element. TCR sequencing for one of these donors revealed an additional skewing for AV1 as well as a selection for an N region encoded argine at position 95 of the BV17 complementarity determining region (CDR)3. Since Arg is not known to participate in Ni complexing, we suppose that this selection is driven by contacts with peptide rather than nickel. However, the CDR1 of BV17 contains a unique combination of amino acids (HDA) that bears similarities to known motifs in Ni-binding proteins or peptides. We therefore propose that the severe hypersensitivity reactions found in BV17 over-expressors may be the result of Ni²⁺ ions bridging the germ-line-encoded BV17 CDR1 loop to corresponding sites in the major histocompatibility complex/peptide complex and thereby creating a superantigen-like enhancement of weak TCR-peptide contacts.     

Differential cyclophosphamide sensitivity of T lymphocytes of the dengue virus-induced suppressor pathway

Dengue type 2 virus (DV) induces a suppressor pathway in mice which involves sequential participation of three subpopulations of T lymphocytes viz. Ts1, Ts2 and T3 cells. In the present study cyclophosphamide (CY) sensitivity of these cells have been investigated. The findings of the present study demonstrate that Ts1 and Ts2 cells are CY-insensitive while T3 cells are CY-sensitive. This supports our earlier conclusion that T3 may be the inducer cells of suppression.     

Polyclonal B cell activators inhibit contact sensitivity to oxazolone in mice by potentiating the production of anti-hapten antibodies that induce T suppressor lymphocytes acting through the release of soluble factors

Polyclonal B cell activators (PBAs) such as purified protein derivative, lipopolysaccharide, Staphylococcus aureus strain Cowan I (StaCwI), and Pseudomonas aeruginosa inhibit contact sensitivity to oxazolone in mice when given 24 h before sensitization. This suppression, transferable from immunodepressed animals to oxazolone-sensitized recipients with immune serum, has been shown to be due to the early appearance of anti-hapten antibodies. These antibodies elicit T suppressor cells which release soluble factor(s) capable of inhibiting the passive transfer of contact sensitivity.