Diesel exhaust, carbon black, and silica particles display distinct Th1/Th2 modulating activity

Certain particulate air pollutants may play an important role in the increasing prevalence of respiratory allergy by stimulating T helper 2 cell (Th2)-mediated immune responses to common antigens. The study described here examined different particles, diesel exhaust particles (DEP), carbon black particles (CBP), and silica particles (SIP) for their immunomodulating capacity in both primary and secondary immune responses in female BALB/C mice. The primary response was studied after subcutaneous injection of 1 mg of particle together with 10 microgram of reporter antigen TNP-OVA (2,4,6-trinitrophenyl coupled to ovalbumin) into the hind paw. Interferon-gamma (IFN-gamma) and interleukin 4 (IL-4) production was assessed in the popliteal lymph node (PLN) at Day 2 and Day 5 after injection by flow cytometry and ELISA. The number of IL-4-containing CD4(+) T cells increased between Day 2 and Day 5 in DEP- and CBP-exposed mice, in contrast to SIP-treated animals. IL-4 production by cultured PLN cells was also significantly increased for DEP- and CBP-treated animals. The secondary response was studied in different organs after an intranasal challenge with TNP-OVA (50 microgram), which was given 4 weeks after the initial subcutaneous injection. Five days after challenge the number of antibody-forming cells (AFCs) was assessed in peribronchial lymph nodes (PBLN), spleen, bone marrow, and PLN, and antibody levels were determined in weekly obtained blood samples. It appeared that all particles acted as adjuvant, but the different particles stimulated distinct types of immune responses to TNP-OVA. DEP-treated animals show high IgG1 and IgE levels in serum and high IgG1 and IgE-forming AFC numbers in PBLN, bone marrow, and spleen. CBP-treated animals show even higher IgG1 and IgE levels and AFC numbers, and in addition display IgG2a production. SIP-injected animals display predominantly IgG2a responses. It is concluded that DEP are able to skew the immune response toward the T helper 2 (Th2) side, whereas SIP stimulate a Th1 response and CBP have a mixed activity, stimulating both Th1 and Th2 responses in this model.     

Temporal changes in cytokine gene expression profiles induced in mice by trimellitic anhydride

Prolonged (13 day) topical exposure of BALB/c strain mice to the chemical respiratory allergen trimellitic anhydride (TMA) induces a selective T helper (Th) 2 profile of cytokine secretion in cells isolated from the draining lymph node. The ability of chemical respiratory allergens to elicit preferential type 2 immune responses is a distinguishing characteristic and provides the theoretical basis for cytokine fingerprinting, a novel approach to hazard identification. This study aimed to further characterize the cytokine expression profile induced by TMA, and to investigate the kinetics of cytokine production at both the protein and mRNA level by comparison of acute (3 day) and chronic (13 day) exposure regimes. Acute exposure resulted in the expression of high levels of mRNA for both Th1- and Th2-type cytokines, including interleukins 4, 10, 15 (IL-4, IL-10, IL-15) and interferon gamma (IFN-gamma), and the inflammatory cytokine IL-6, as determined by ribonuclease protection assay (RPA). However, following chronic exposure marked down-regulation of message for IL-6 and IFN-gamma was observed along with concomitant up-regulation of IL-4 and IL-10 expression. These cytokine mRNA profiles were broadly paralleled at the protein level. There was also a marked increase with time of mRNA for the Th2 cytokine IL-9, a cytokine not associated previously with chemical allergy. These data show that as the immune response to TMA develops, the cytokine gene expression profile of allergen-activated lymph node cells evolves from a mixed Th1/Th2 phenotype to a more polarized Th2 profile.     

Popliteal lymph node responses to acetone and ethanol differ from those induced by streptozotocin

The popliteal lymph node (PLN) assay was proposed to detect the potential of immunotoxicants for inducing systemic autoimmune-like reactions, but also xenobiotics that are sensitizing or exert immunostimulatory properties. Results on over 100 chemicals, mostly pharmaceuticals, are available with the PLN assay and show many correlations between rodent data and the clinical experience. A major issue is that the mechanisms involved have not been fully elucidated. In order to provide mechanistic clues to improve the predictability of the PLN assay, the effects of streptozotocin (STZ) were compared to those of ethanol and acetone in normal C57Bl/6 mice as well as mice depleted in CD4⁺ or CD8⁺ T-cells by treatment with specific monoclonal antibodies. STZ, ethanol and acetone gave similar positive responses in normal mice. Neither CD4⁺ nor CD8⁺ T-cell depletion influenced the PLN responses to ethanol or acetone, whereas CD8⁺ in contrast to CD4⁺ T-cell depletion abolished the response to STZ. There was an increase in the production of IL-6 and IFN- mRNAs measured by RT-PCR in STZ-, but not in ethanol- or acetone-treated normal mice. The production of TNF, IL-1, IL-1, IL-2R and IL-12 mRNAs was increased whatever the treatment, but increases were 2- to 3-fold greater after STZ than ethanol or acetone. These results suggest that PLN responses to primary irritants such as ethanol and acetone essentially reflect non-specific inflammation, whereas PLN responses to an autoimmunogenic compound such as STZ involve CD8⁺ T lymphocytes and the production of IFN- and IL-6. These findings may prove useful to improve the predictability of the PLN assay.     

Positive responses to imipramine in the popliteal lymph node assay are due to primary irritation

The popliteal lymph node (PLN) assay has long been proposed as a tool to detect immunotoxicants with the potential to induce systemic autoimmunity. A major problem hampering the further validation of this assay is the need to rule out irritants that cause false-positive PLN responses. The anti-depressant, imipramine, has not been reported to induce systemic autoimmune reactions in treated patients, but has been repeatedly found positive in the PLN assay, suggesting that this is a false-positive response. To test this hypothesis, the effects of imipramine were compared to those of 50% ethanol in C57B1/6 mice. Footpad edema was evidenced in the few days after injection of both ethanol and imipramine. T-cell depletion using monoclonal antibodies against either CD4+ or CD8+ T-lymphocytes prior to the PLN assay did not influence the responses to either ethanol or imipramine. Cytokine (TNFalpha, IL-1alpha, IL-1beta, IL-2R, IL-6, IL-12 and IFN-gamma) fingerprinting of the PLNs after injection of ethanol and imipramine evidenced the same pattern of responses. These results indicate a closely similar pattern of responses following the footpad injection of either imipramine or ethanol. The conclusion can be drawn that imipramine induces positive responses in the PLN assay via primary (nonspecific) irritation.     

Intranasal IL-12 produces discreet pulmonary and systemic effects on allergic inflammation and airway reactivity

IL-12 modulates T cell responses between helper T cells Th2 and Th1; however, the therapeutic potential of IL-12 for allergic diseases either directly or as an adjuvant in allergen therapy has been controversial. The role of intranasal IL-12 as an adjuvant in modulating the grass pollen allergen (GAL) therapy-induced systemic immune response and lung-specific inflammation and airway reactivity was examined in this study using a mouse model of established allergic asthma. The effects of intranasal or nebulized IL-12 with or without intranasal anti-IFN-gamma antibody were examined in groups of control and allergen-sensitized or -challenged mice. T cell cytokine patterns, antibody response profiles, pulmonary inflammation and airway reactivity were examined. Intranasal IL-12 was found to be more effective in the Th2-Th1 shifting of immune response and anti-inflammatory activity in the lung compared to nebulized IL-12 at the given doses. Intranasal IL-12 significantly decreased production of IFN-gamma, eotaxin and LTC4/D4/E4 in the lung and decreased eosinophil infiltration, resulting in attenuated airway hyper-responsiveness in GAL-sensitized (GS) mice. In contrast, intranasal IL-12 significantly increased IFN-gamma production in the thoracic lymph node cultures and decreased the IL-5/IFN-gamma ratio, suggesting a Th2-Th1 shift. Also, intranasal IL-12 increased GAL-specific IgG2a antibody response, while the IgE response remained unaffected. The systemic effects of IL-12 were IFN-gamma dependent. IL-12 induces differential expression of its own receptor beta1 and beta2 subunits in the lung tissues to augment IL-12 responsiveness. Together, these results demonstrate that intranasal IL-12 is effective in shifting the systemic immune response in the direction of Th1 in IFN-gamma-dependent manner, while decreasing pulmonary inflammation and airway reactivity independent of IFN-gamma. Thus, intranasal delivery of IL-12 may provide an approach for the treatment of asthma and may be useful as an adjuvant in local nasal immunotherapy (IT) and in asthma.     

Assessment of preferential T-helper 1 or T-helper 2 induction by low molecular weight compounds using the local lymph node assay in conjunction with RT-PCR and ELISA for interferon-gamma and interleukin-4

The local lymph node assay (LLNA) is a new and promising test in mice used to identify contact allergens by means of dermal exposure. Experimentally this assay, which comprises a sensitizing phase only, is also used to identify respiratory allergens. Another, experimentally used test in mice to identify allergens is also based on dermal exposure, but comprises both a sensitizing and effector phase. In this latter test, it has been shown that contact allergens preferentially induce a T-helper 1 (TH1) response, whereas respiratory allergens preferentially induce a T-helper 2 (TH2) response. These responses can be discriminated on the basis of cytokine production, such as IFN-gamma, which is produced by TH1 cells, and IL-4, which is produced by TH2 cells. The aim of the study was to establish whether the LLNA was sufficient to not only identify allergens but also mark them as either a contact or a respiratory allergen. To this end, LLNA responses to the contact allergen dinitrochlorobenzene (DNCB) and the respiratory allergen trimellitic anhydride (TMA) were determined using IFN-gamma and IL-4 mRNA expression and production as parameters. Topical application of TMA resulted in a threefold higher lymphocyte proliferation compared to DNCB 3 and 5 days after the first application, while a similar proliferation was found from Day 7 and onward. RT-PCR showed a similar induction of IFN-gamma and IL-4 mRNA expression. While both DNCB and TMA induced IFN-gamma production, TMA but not DNCB induced IL-4 production. Thus, only IL-4 production seemed a suitable parameter to discriminate between the two compounds. In a second study, the respiratory allergens toluene-2,4-diisocyanate (TDI) and phthalic anhydride (PA) were also assayed 7 days after the first application. Topical application of DNCB and PA resulted in a similar lymphocyte proliferation, while application of TMA and TDI resulted in a 1.8-fold higher proliferation. IFN-gamma production was similar for DNCB, TMA, and TDI, and fourfold lower for PA, while IL-4 production was similar for TMA, TDI, and PA, and 24-fold lower for DNCB. In summary, both studies showed induction of IL-4 production by respiratory allergens, with little or no induction by the contact allergen, holding promise for the possibility of identifying respiratory allergens within the LLNA by measuring IL-4 production 7 days after the first application.     

Effect of Th2 cytokine antagonist treatments on chemical-induced allergic response in mice

To understand better the cellular and molecular mechanisms of chemical-induced occupational asthma, we examined the effects of the Th2 cytokine antagonists interferon-gamma (IFN-gamma), interleukin (IL)-12 and anti-IL-4 on the balance of the Th1/Th2 response induced by trimellitic anhydride (TMA) and phthalic anhydride (PA). Eight- to ten-week-old BALB/c mice were assigned to be exposed to either TMA or PA plus one of these Th2 cytokine antagonists. Both TMA (25% and 12.5% for sensitization and challenge, respectively) and PA (12.5% and 6.25% for sensitization and challenge, respectively) induced a Th2 response marked by an increasing production of IL-4 and IL-10 in the supernatants of ex vivo spleen cells cultured with concanavalin A and also of serum total IgE. Co-administration of IL-12 and antiIL-4 deviated these PA- or TMA-induced Th2 responses, as judged by an increasing serum total IgG2a production (up to 14-fold), associated with a slight decrease of IL-4 in three out of four experiments and of IL-10 in all four experiments. Co-administration of IFN-gamma, however, had only one weak effect. These findings suggest that the chemical-induced Th2-biased response may be diverted during an induction period by exogenous administration of the Th2 cytokine antagonists, particularly IL-12 and the anti-IL-4 antibody. These results would significantly enhance our understanding of the Th1/Th2 response induced by chemicals.     

Curcumin inhibits Th1 cytokine profile in CD4+ T cells by suppressing interleukin-12 production in macrophages.

1 Interleukin-12 (IL-12) plays a central role in the immune system by driving the immune response towards T helper 1 (Th1) type responses which are characterized by high IFN-gamma and low IL-4 production. In this study we investigated the effects of curcumin, a natural product of plants obtained from Curcuma longa (turmeric), on IL-12 production by mouse splenic macrophages and the subsequent ability of these cells to regulate cytokine production by CD4+ T cells. 2 Pretreatment with curcumin significantly inhibited IL-12 production by macrophages stimulated with either lipopolysaccharide (LPS) or head-killed Listeria monocytogenes (HKL). 3 Curcumin-pretreated macrophages reduced their ability to induce IFN-gamma and increased the ability to induce IL-4 in Ag-primed CD4+ T cells. Addition of recombinant IL-12 to cultures of curcumin-pretreated macrophages and CD4+ T cells restored IFN-gamma production in CD4+ T cells. 4 The in vivo administration of curcumin resulted in the inhibition of IL-12 production by macrophages stimulated in vitro with either LPS or HKL, leading to the inhibition of Th1 cytokine profile (decreased IFN-gamma and increased IL-4 production) in CD4+ T cells. 5 These findings suggest that curcumin may inhibit Th1 cytokine profile in CD4+ T cells by suppressing IL-12 production in macrophages, and points to a possible therapeutic use of curcumin in the Th1-mediated immune diseases.     

Inhibition of interleukin-12 production by auranofin, an anti-rheumatic gold compound, deviates CD4(+) T cells from the Th1 to the Th2 pathway

1. Interleukin-12 (IL-12) may play a central role in the development and progression of rheumatoid arthritis by driving the immune response towards T helper 1 (Th1) type responses characterized by high IFN-gamma and low IL-4 production. In this study we investigated the effect of auranofin (AF), an anti-rheumatic gold compound, on IL-12 production in mouse macrophages and dendritic cells, and studied whether AF-mediated inhibition of IL-12 production could regulate a cytokine profile of antigen (Ag)-primed CD4(+) Th cells. 2. Treatment with AF significantly inhibited IL-12 production in lipopolysaccharide (LPS)-stimulated macrophages and also in CD40L-stimulated dendritic cells. AF-pretreated macrophages reduced their ability to induce IFN-gamma and increased the ability to induce IL-4 in Ag-primed CD4(+) T cells. AF did not influence the cell surface expression of the class II MHC molecule and the costimulatory molecules CD80 and CD86. 3. Addition of recombinant IL-12 to cultures of AF-pretreated macrophages and CD4(+) T cells restored IFN-gamma production in Ag-primed CD4(+) T cells. 4. The in vivo administration of AF resulted in the inhibition of IL-12 production by macrophages stimulated in vitro with LPS or heat-killed Listeria monocytogenes (HKL), leading to the inhibition of Th1 cytokine profile (decreased IFN-gamma and increased IL-4 production) in Ag-primed CD4(+) T cells. 5. These findings may explain some known effects of AF including anti-rheumatic effects and the inhibition of encephalitogenicity, and point to a possible therapeutic use of AF in the Th1-mediated immune diseases such as autoimmune diseases.     

The IgE adjuvant effect of particles: characterisation of the primary cellular response in the draining lymph node

Diesel exhaust particles, and polystyrene particles (PSP) as a model for the insoluble particle core, have an adjuvant effect on allergen-specific IgE production in mice. We therefore examined the primary immune response in the draining popliteal lymph node (PLN) to the allergen ovalbumin (OVA) injected together with polystyrene particles into the footpad of BALB/cA mice. Similar numbers of particle-containing cells were observed in the draining lymph node on day 1 after injection of PSP alone or OVA + PSP, the numbers increasing continuously until day 21. The total lymph node cell numbers increased three to four times in the OVA + PSP group compared to both OVA and PSP groups, peaking on day 5. The increase in B cell numbers was twice the increase in T cell numbers. On day 5, OVA + PSP increased the expression of most surface markers measured (MHC class II, CD86, CD23, CD69) compared to OVA and PSP. Further, the ex vivo production of IL-4 and IL-10 by PLN cells from OVA + PSP-injected animals was increased. In conclusion, whereas PSP alone did not influence any of the immunologic markers studied, the adjuvant effect of PSP on the IgE antibody response to OVA was associated with an early increased primary cellular response in the draining lymph node.     

Retinoid-mediated inhibition of interleukin-12 production in mouse macrophages suppresses Th1 cytokine profile in CD4(+) T cells

Interleukin-12 (IL-12) plays a central role in the immune system by driving the immune response towards T helper 1 (Th1) type responses characterized by high IFN-gamma and low IL-4 production. In this study we investigated whether retinoid-mediated inhibition of interleukin-12 production in mouse macrophages could regulate cytokine profile of antigen (Ag)-primed CD4(+) Th cells. Pretreatment with retinoids (9-cis-RA, all-trans-RA, TTNPB) significantly inhibited IL-12 production by mouse macrophages stimulated with lipopolysaccharide (LPS) or heated-killed Listeria monocytogenes (HKL). Retinoid-pretreated macrophages reduced their ability to induce IFN-gamma and increased the ability to induce IL-4 in Ag-primed CD4(+) T cells. Addition of recombinant IL-12 to cultures of retinoid-pretreated macrophages and CD4(+) T cells restored IFN-gamma production in CD4(+) T cells. The in vivo administration of 9-cis-RA resulted in the inhibition of IL-12 production by macrophages stimulated in vitro with either LPS or HKL, leading to the inhibition of Th1 cytokine profile (decreased IFN-gamma and increased IL-4 production) in CD4(+) T cells. These findings may explain some known effects of retinoids including the inhibition of encephalitogenicity, and point to a possible therapeutic use of retinoids in the Th1-mediated immune diseases such as autoimmune diseases.     

Exposure of mice to the nitroso metabolite of sulfamethoxazole stimulates interleukin 5 production by CD4+ T-cells

Sulfamethoxazole hypersensitivity may be caused by production of the protein-reactive metabolite nitroso sulfamethoxazole (SMX-NO) and interaction of SMX-NO with T-cells. We have characterised the nature of the immune response induced by administration of sulfamethoxazole, sulfamethoxazole metabolites and nitrosobenzene to BALB/c mice. Drugs were administered over a 13-day period to induce polarised cytokine secretion profiles. Proliferation was measured by [(3)H] thymidine incorporation. Cytokine secretion was monitored by ELISA. Results were compared with those provoked by exposure to type 1 and type 2 chemical allergens, 2,4-dinitrochlorobenzene (DNCB) and trimellitic anhydride (TMA). CD4(+) or CD8(+) T-cells were depleted ex vivo to identify the primary source of cytokines. Lymph node activation was observed following treatment with DNCB, TMA, nitrosobenzene and SMX-NO, but not with sulfamethoxazole or sulfamethoxazole hydroxylamine (SMX-NHOH). DNCB and TMA induced type 1 and type 2 cytokine profiles, respectively. SMX-NO treatment stimulated the production of high levels of IL-5, variable amounts of IFN-gamma, and relatively low levels of IL-10 and IL-4. Nitrosobenzene-activated lymph node cells secreted only low levels of IFN-gamma and IL-5. Depletion of CD4(+) or CD8(+) T-cells from SMX-NO stimulated lymph node cells revealed that CD4(+) T-cells were the major source of IL-5. In conclusion, the data presented indicates that subcutaneous administration to mice of SMX-NO, but not the parent drug, stimulated the secretion of high levels of IL-5 from activated CD4(+) T-cells, which is consistent with the clinical profile of the drug.     

Assessment of preferential Th1 or Th2 induction by low-molecular-weight compounds using a reverse transcription-polymerase chain reaction method: comparison of two mouse strains, C57BL/6 and BALB/c.

The aim of this study was to examine whether the RT-PCR method for various Th1/Th2 cytokines is appropriate for determination of response to allergens using C57BL/6 and Balb/c mice, which are known to preferentially demonstrate Th1 and Th2 responses, respectively. To this end, both strains of mice were sensitized by skin painting with the contact allergen dinitrochlorobenzene (DNCB) or the respiratory allergen trimellitic anhydride (TMA). We used the sensitizing protocol adopted by Kimber and coworkers (Toxicology 103, 63-73, 1995). At various time points after the last application, the levels of mRNA expression for Th1-type cytokines IFN-gamma, IL-18, and IL-12p40, as well as receptor IL-18R, and the Th2-type cytokine IL-4 and the receptor ST2L, in lymph nodes were measured. The results suggest that differential expression of IL-12p40 and IL-4 mRNA after 24 h allows clear discrimination between DNCB and TMA in C57BL/6 mice, more obviously than in Balb/c mice. Furthermore, to examine this method, C57BL/6 mice were exposed to OXA, DNFB, and TNCB (Th1-predominant allergens) or PA, TDI, and MDI (Th2-predominant allergens). Elevation of IL-12p40 expression was significant with the Th1 inducers, while the level of IL-4 was higher with Th2-predominant allergens. The results of the present study demonstrate, for the first time, that differential expression of IL-12p40 and IL-4 in C57BL/6 mice may be useful as a parameter for assessing influence of contact and respiratory allergens.     

当归多糖组分AP-3诱生小鼠脾细胞IL-2和IFN-γ的作用

目的研究当归多糖组分AP-3对细胞因子IL-2和IFN-γ的诱生作用，以探讨其免疫调节的特点。方法 流式细胞术测定培养的脾细胞中CD4⁺细胞比例；酶联免疫法测定培养上清液中IL-2和IFN-γ的浓度；RT-PCR法测定IL-2和IFN-γ mRNA的转录水平。结果AP-3在0.6～2 μmol·L^-1，能显著提高培养脾细胞CD4⁺细胞的百分率；在2～6 μmol·L^-1，AP-3时间、剂量依赖性地增加培养的细胞上清液中IL-2的浓度和细胞内IL-2 mRNA的转录水平，而对于IFN-γ和IFN-γ mRNA，则先升高后降低，并呈现剂量依赖性。结论当归多糖能够促进IL-2和IFN-γ的分泌，激活Th1细胞，从而发挥免疫调节作用。     

Ambient air particles from four European cities increase the primary cellular response to allergen in the draining lymph node

In the RAIAP (respiratory allergy and inflammation due to ambient particles) project, qualitative properties of ambient air particles from Amsterdam, Oslo, Lodz and Rome were investigated in relation to inflammation and allergy. Most collected particle fractions were found to increase the allergen-specific IgE and IgG2a responses after subcutaneous injection of particles with allergen in mice. However, some fractions appeared to skew the antibody response towards more Th1- or Th2-associated antibody isotypes, and the fine fractions were found to be more potent than the coarse fractions with regard to IgE adjuvant activity. In the present study we investigated the cellular response in the draining lymph node 5 days after a subcutaneous injection of selected RAIAP particle fractions. The particles (100 microg) were injected into both hind footpads of BALB/cA mice, in the presence or absence of the allergen ovalbumin (OVA, 50 microg). We also studied if the coarse and fine RAIAP particle fractions affected the cellular responses to OVA differently. The number of lymph node cells, as well as the relative number of B and T lymphocytes and T helper cells were determined. Expression of cell surface molecules (MHC class II, CD86 and CD23) and ex vivo cytokine production (IL-4, IL-10 and IFN-gamma) by the lymph node cells were measured. Overall, particles in the presence of allergen enhanced the levels of the various cellular parameters compared to allergen alone or particles alone. In the absence of allergen, ambient air particles, in contrast to diesel exhaust particles, marginally affected some cellular parameters. By histological examination of the lymph node, the particles appeared to be scattered between the lymphocytes, often localised within macrophage-like (acid phosphatase positive) cells. The cell parameters measured could, for the individual sample, neither predict the degree of a Th2- or Th1-skewed antibody response, nor the stronger antibody adjuvant capacity of the fine than the coarse particle fractions. In conclusion, we have shown that coarse and fine ambient air particles from different European cities enhance the cellular response in the draining lymph node after injection with an allergen. In the absence of allergen, ambient particles only marginally affected the cellular parameters.     

The reactive D-glucopyranose moiety of streptozotocin is responsible for activation of macrophages and subsequent stimulation of CD8+ T cells

The antitumor drug streptozotocin (STZ) is commonly used as a diabetogenic compound in animal models. At relatively low doses, STZ-induced beta cell destruction is associated with Th1-driven type 1 immune reactions, including macrophages (MPhi) and IFN-gamma-producing CD8(+) T cells. STZ induces similar Th1-dependent effects in the popliteal lymph node assay (PLNA), and because this assay allows straightforward examination of early immunostimulating processes, the PLNA was used to further examine the importance of MPhi and structural properties of STZ in relation to the induction of type 1 immune responses. Results show that elimination of MPhi with clodronate-containing liposomes prior to exposure to STZ prevents the occurrence of some (CD8(+) T cell activation, IFN-gamma production, and tissue destruction) but not all (IgG2a formation) type 1 immune responses. It appeared that stimulation of MPhi depends on the d-glucopyranose moiety of STZ, as well as on the intact reactive N-methyl-N-nitrosourea (MNU) moiety. However, the MNU moiety suffices to induce IgG2a formation. In addition, STZ-derived nitric oxide may have modulating effects on the elicitation of STZ-induced immune responses. Present results support the idea that MPhi activation is indispensable for the STZ-induced tissue destructive type 1 responses and that various STZ-induced type 1 immune responses are differently regulated.     

In vivo effects of deoxyspergualin (NKT-01) on lymphocyte activation in response to alloantigens

We studied the effects of deoxyspergualin (NKT-01) on the events of lymphocyte activation in vivo by inoculating mice in the footpad with allogeneic spleen cells, and compared the effects with those of cyclosporin A (CyA). The administration of NKT-01 increased the numbers of cells recovered from the popliteal lymph node (PLN) 7 days after inoculation, but inhibited the proliferation of these cells in the presence of exogenous interleukin 2 (IL-2). NKT-01 enhanced IL-2 production, but suppressed the production of macrophage activating factor (MAF) in the mixed lymphocyte reaction between the PLN cells and allogeneic spleen cells treated with mitomycin C. CyA decreased the numbers of PLN cells little, and suppressed the response to exogenous IL-2 and the production of both IL-2 and MAF. Results with tumor cells used as allogeneic cells suggested that there was a close relationship between the suppression of MAF production by NKT-01 and its inhibition of allograft rejection. The findings showed that NKT-01 inhibited both the MAF production by and the response to IL-2 of PLN cells, and that these effects were involved in the suppression of allograft rejection by NKT-01.