Potential involvement of dendritic cells in delayed-type hypersensitivity reactions to beta-lactams

BACKGROUND: Although the involvement of T cells in delayed reactions to drugs has been studied, little is known about the interaction between the drug and the antigen-presenting cells. Dendritic cells (DCs) are professional antigen-presenting cells essential for initiating T-cell responses. Their ability is regulated in a process known as maturation, by which they modulate the effector immune response. OBJECTIVES: We studied the role of DCs in subjects who had a delayed-type hypersensitivity reaction to amoxicillin to assess the effect on the pattern of maturation and determine the capacity of DCs to activate T lymphocytes. METHODS: We examined the consequences of the interaction between monocyte-derived DCs, lymphocytes, and amoxicillin by means of phenotypic and functional studies, including endocytosis, proliferation, and cytokine production. RESULTS: Amoxicillin drove DCs from hypersensitive subjects to a phenotypic and functional semimature status, inducing a T-cell proliferation response. CONCLUSIONS: In delayed reactions to amoxicillin, DCs play a relevant role in inducing the T-cell responses. These results are useful not only to understand the mechanism but potentially as a possible approach to diagnosis. CLINICAL IMPLICATIONS: A better understanding of T-cell and DC involvement in delayed-type hypersensitivity reactions is needed. This in vitro assay might provide clues to the diagnostic evaluation of patients allergic to penicillins.     

Suppression of delayed-type hypersensitivity mediated by macrophage-like cells in mice with experimental liver injury.

Systemic hyporesponsiveness after ingestion of a protein antigen (oral tolerance) depends on antigen processing by the gut and the actions of immunoregulatory T cells. We have examined the effects of a graft-versus-host reaction (GvHR) on oral tolerance, since both immune status and intestinal function are altered in GvHR. The GvHR was induced in unirradiated (CBA X BALB/c)F1 mice by intraperitoneal injection of CBA spleen cells. The tolerance of systemic humoral immunity and of delayed-type hypersensitivity normally found in mice fed 25 mg ovalbumin (OVA) was partially abrogated from 1 to 3 weeks after induction of the GvHR. In addition, mice with GvHR had a persistent enhancement of systemic immunity to OVA, and this was associated with an augmented ability of spleen cells to present OVA to primed T cells. The phagocytic activity of the reticuloendothelial system, as established by carbon clearance tests, was not altered by the GvHR. These findings suggest that enhanced antigen-presenting cell activity interferes with the induction of oral tolerance, and may be another pathogenetic mechanism of intestinal hypersensitivity disease.     

P-selectin directs T lymphocyte-mediated injury in delayed-type hypersensitivity responses: studies in glomerulonephritis and cutaneous delayed-type hypersensitivity

The role of P-selectin in T lymphocyte accumulation and injury was studied in delayed-type hypersensitivity (DTH) responses in the skin and glomeruli of rats. Sprague Dawley rats were sensitized to sheep globulin and challenged 5 days later in the skin by subcutaneous injection and simultaneously in glomeruli by intravenous injection of a subnephritogenic dose of sheep anti-rat glomerular basement membrane globulin. This resulted in cutaneous and glomerular T lymphocyte-dependent macrophage influx and injury characteristic of DTH. Up-regulation of P-selectin expression on endothelial cells was observed in both inflammatory lesions. Treatment of rats with anti-CD5 antibody immediately prior to antigen challenge prevented the development of injury as assessed by measurement of proteinuria and skin swelling, as well as local T cell and macrophage accumulation in the glomerulus and in the skin, but did not block up-regulation endothelial cell P-selectin. Treatment with anti-CD4 antibody produced similar results. Blocking P-selectin in vivo with a functionally inhibitory antibody prevented development of proteinuria and skin swelling following antigen challenge. Local accumulation of T cells and macrophages was markedly attenuated in glomeruli and the skin and up-regulation of endothelial cell P-selectin was prevented. These data demonstrate that P-selectin is locally up-regulated on endothelial cells in T cell-dependent glomerular and cutaneous inflammation and suggests a pivotal functional role for P-selectin in local T cell recruitment and subsequent injury in DTH.     

三氯化钆对移植肝缺血再灌注损伤的保护作用

背景：三氯化钆能抑制枯否细胞的活化,降低其吞噬活性,并减少枯否细胞激活后的肿瘤坏死因子α及白细胞介素1 释放,从而减轻肝脏缺血再灌注损伤。 目的：观察三氯化钆对大鼠移植肝缺血再灌注损伤的影响并探讨其作用机制。 方法：供、受体均采用雄性SD大鼠,将实验动物随机分为3组。采用改良连续缝合进行肝上下腔静脉重建的Kamada’s“两袖套法”建立大鼠肝移植模型。①假手术组：不行肝移植,游离肝脏、结扎静脉后关腹,不处理及用药。②生理盐水组：热缺血时间0-5 min,供肝冷保存时间为2 h,移植前连续3 d 经尾静脉向受鼠注射生理盐水,移植后再经尾静脉注射生理盐水1次。③三氯化钆组：热缺血时间为0-5 min,冷保存时间为2 h,移植前连续3 d 经尾静脉向受鼠注射0.5%三氯化钆,移植后再经尾静脉注射0.5%三氯化钆1次。24 h后处死大鼠进行相应指标检测。 结果与结论：与假手术组比较,三氯化钆组、生理盐水组血清丙氨酸转氨酶、谷氨酸转氨酶、碱性磷酸酶、γ-谷氨酰转移酶水平明显升高(P < 0.05);三氯化钆组各指标较生理盐水组有所减轻(P < 0.05)。病理组织学检查发现生理盐水组、三氯化钆组病变范围及缺血再灌注损伤程度均较假手术组明显增加。与生理盐水组比较,三氯化钆组血清白细胞介素1、肿瘤坏死因子α及凋亡指数明显降低(P < 0.05),淤血、空泡变性及坏死Suzuki’s评分均较低(P < 0.05)。提示三氯化钆在一定程度上是通过封闭枯否细胞吞噬并抑制细胞因子的释放实现对移植肝缺血再灌注损伤的保护机制。     

Regulation of delayed-type hypersensitivity IV. Antigen-specific suppressor cells for delayed-type hypersensitivity induced by lipopolysaccharide and sheep erythrocytes in mice.

Mice injected subcutaneously with 1 x 10(8) sheep red blood cells (SRBC) developed high levels of delayed-type hypersensitivity (DTH) to SRBC 4-8 days after injection. Such DTH was suppressed when 100 microgram lipopolysaccharide (LPS) was injected intravenously 1-2 days before or at the time of SRBC injection. This suppression of DTH was transferable by spleen, lymph node, thymus and bone marrow cells to sensitized or normal syngeneic recipients, but could not be transferred by serum. Suppressor cells were not induced by LPS alone or SRBC alone, and they were antigen-specific since DTH to chicken red blood cells was not affected. The suppressor cells appeared in the spleen in optimum number 3-4 days after induction. They were theta-negative and Ig-positive as judged by antiserum plus complement treatment and by Ig rosette separation. Attempts to obtain soluble suppressor factor from the suppressor cells by sonication or in vitro incubation were unsuccessful. Mitomycin C treatment of the suppressor cells completely abolished the suppressor activity. Thus, LPS, in conjunction with antigen, appears to induce a population of specific suppressor B cells which are capable of regulating T cell function.     

肝移植后缺血再灌注损伤大鼠诱导细胞凋亡中的一氧化氮

背景：由诱生型一氧化氮合酶产生的一氧化氮,是肝脏缺血再灌注损伤中病理生理学改变的一个重要因素。 目的：探讨一氧化氮在肝移植缺血再灌注诱导的肝细胞早期凋亡的影响以及相关基因caspase-3的表达情况。 方法：受体鼠72只随机数字表法均分成移植组、精氨酸组及L-硝基精氨酸甲酯组,均建立原位肝移植模型,后2组大鼠在开放血流前5 min于股静脉注射可升高血清一氧化氮水平的精氨酸或一氧化氮抑制剂L-硝基精氨酸甲酯。移植造模后剩余的24只大鼠设为假手术组。 结果与结论：血清谷草转氨酶活性比较,精氨酸组<移植组P < 0.01);血清一氧化氮浓度,精氨酸组>移植组>L-硝基精氨酸甲酯组;早期凋亡的高峰期为再灌注后3 h,肝细胞的活细胞数比例及肝组织中caspase-3的表达,精氨酸组<移植组< L-硝基精氨酸甲酯组。说明,一氧化氮对大鼠对肝移植缺血再灌注后肝细胞早期凋亡具有保护作用,且该作用可能主要通过下调caspase-3基因的表达。     

Depression of delayed-type hypersensitivity in mice with hypothalamic lesion induced by monosodium glutamate: involvement of neuroendocrine system in immunomodulation.

Delayed-type hypersensitivity (DTH) was depressed in mice that had been treated with monosodium glutamate (MSG) in their suckling period. Analysis of the DTH depression by use of the macrophage migration inhibition assay showed dysfunction of DTH effector T cells. The neuronal loss of nuclei in the hypothalamus, which elaborates the corticotropin-releasing factor and the hypersecretion of adrenocorticotrophic hormone, was observed in the MSG-treated mice. Therefore, DTH response may be modulated by the neuroendocrine system.     

Carotid body chemosensory excitation induced by nitric oxide: involvement of oxidative metabolism

Nitric oxide (NO) produces a dual effect on carotid body (CB) oxygen chemoreception. At low concentration, NO inhibits chemosensory response to hypoxia, while in normoxia, medium and high [NO] increases the frequency of carotid chemosensory discharges (f(x)). Since NO and peroxynitrite inhibit mitochondrial respiration, it is plausible that the NO-induced excitation may depend on the mitochondrial oxidative metabolism. To test this hypothesis, we studied the effects of oligomycin, FCCP and antimycin A that produce selective blockade of hypoxic and NaCN-induced chemosensory responses, leaving nicotinic response less affected. CBs excised from pentobarbitone-anaesthetised cats were perfused in vitro with Tyrode (P(O(2)) approximately 125 Torr, pH 7.40 at 38 degrees C). Hypoxia (P(O(2)) approximately equal 30 Torr), NaCN and nicotine (1-100 microg) and S-nitroso-N-acetylpenicillamide (SNAP, 300-600 microg) increased f(x). Oligomycin (12.5-25 microg), antimycin A (10 microg) and FCCP (5 microM) transiently increased f(x). Subsequently, chemosensory responses to hypoxia, NaCN and SNAP were reduced or abolished, while the response to nicotine was less affected. The electron donor system tetramethyl-p-phenylene diamide and ascorbate that bypasses the electron chain blockade produced by antimycin A, restores the excitatory responses to NaCN and SNAP. Present results suggest that the chemoexcitatory effect of NO depends on the integrity of mitochondrial metabolism.     

迟发型变态反应机制致肝损伤的动物模型的建立

将ｐｉｃｒｙｌ ｃｈｌｏｒｉｄｅ（ＰＣ）所致的迟发型变态反应（ＰＣ－ＤＴＨ）导入肝脏诱发肝损伤，方法是将ＰＣ涂于昆明种小鼠腹部致敏，６天后用ＰＣ在肝脏攻击，测量血清谷丙转氨酶（ｓＧＰＴ）的活性并进行肝组织病理学检查结果发现，ｓＧＰＴ活性明显上升，肝细胞坏死、门管区粒细胞和淋巴细胞浸润等。在ＰＣ致敏前用环磷酰胺处理明显地增强了这种肝损伤。但给正常小鼠肝脏注射ＰＣ则不能诱发肝损伤。这些结果表明，该肝损     

Suppression of the delayed-type hypersensitivity and cell-mediated immune responses to Listeria monocytogenes induced by Pseudomonas aeruginosa.

Pseudomonas aeruginosa-mediated suppression of the immune response to Listeria monocytogenes was investigated in mice. Because delayed-type hypersensitivity (DTH) footpad swelling to L. monocytogenes was suppressed equally in lipopolysaccharide-responsive and -hyporesponsive mouse strains, the lipopolysaccharide component of P. aeruginosa could not have been the suppressive agent. Mucoid P. aeruginosa cells were no more suppressive than their nonmucoid revertants; therefore, mucoid coating was not an additional immunosuppressive element. Interleukin-1 and macrophage inhibitory factor production to L. monocytogenes and clearance of L. monocytogenes from mouse spleens were all decreased by prior Pseudomonas infection, indicating that cell-mediated immunity, as well as DTH, was decreased to a sublethal Listeria dose. The timing of Pseudomonas exposure relative to Listeria sensitization was varied. P. aeruginosa injected 24 or 6 h before or at the same time as L. monocytogenes depressed DTH to Listeria challenge 7 days later. Animals treated in this way could not respond to reinfection with L. monocytogenes at 13 days. P. aeruginosa administered to L. monocytogenes-sensitized mice at the time of footpad challenge was suppressive, but these mice responded normally upon reinfection. It appears that P. aeruginosa induced two types of suppression to L. monocytogenes: a transient suppression, affecting DTH challenge but not resensitization, and a longer lasting suppression that did not permit mice exposed to P. aeruginosa at the time of Listeria sensitization to respond to subsequent Listeria exposure.     

Increased resistance and depressed delayed-type hypersensitivity to Listeria monocytogenes induced by pretreatment with lipopolysaccharide.

Intravenous injection of a small dose of lipopolysaccharide 24 h before infection with Listeria monocytogenes enhanced the resistance of mice to this organism. This protective effect of lipopolysaccharide related to the ability of nonimmune macrophages to inhibit bacterial proliferation in livers and spleens. Surprisingly, lipopolysaccharide-treated mice exhibited inferior acquired immunity, as measured by adoptive transfer of immunity to normal mice, delayed-type hypersensitivity to Listeria antigens, and uptake of tritiated thymidine by lymphocytes in the spleen. These results support the view that lipopolysaccharide stimulates a highly effective anti-Listeria immunity via the macrophage component, despite interference with the lymphocyte component.     

Strong delayed-type hypersensitivity induced against house dust mite antigens in the mice

The aim of this study was to assess the antigenicity of house dust mite antigens using delayed-type hypersensitivity (DTH) responses in mice. The crude extracts of Dermatophagoides pteronyssinus and Dermatophagoides farinae induced strong DTH responses and was transferred with T cells. Assessment of DTH responses to the house dust revealed that substantial cross-reactivity at T-cell level was observed between these two mite extracts. Almost all the fractions of the extract of D. pteronyssinus, which has a molecular weight of between 10 and 100 kilodaltons, elicited strong DTH responses. It was found that antigenicity of the mite extract was reduced by chemical denaturation with tannic acid.     

Development of delayed-type hypersensitivity to hog cholera

Leukocyte migration inhibition test showed that pigs with classical swine fever develop delayed type hypersensitivity. The highest migration inhibition (65-85%) was observed in animals with the acute form, on day 3 after infection, or directly before death, or in animals immunized with reactogenic strain with clinical signs of disease. In some pigs with acute form the migrating capacity of leukocytes was restored on days 7-8 postinfection. Leukocyte migration inhibition factor is detected in the sera of pigs starting from day 3 after infection with the virulent strain. The degree of delayed type hypersensitivity correlated with the outcome of classical swine fever.     

Protective effects of pentoxifylline on acute liver injury induced by thioacetamide in rats

Pentoxifylline (PTX) is a non-selective phosphodiesterase inhibitor with the effects of antioxidation, anti-inflammation and anti-fibrosis that has been shown to induce damage in liver. The purpose of this study is to investigate the effects and possible mechanisms of PTX on thioacetamide (TAA)-induced acute liver injury in rats. Male Sprague-Dawley (SD) rats were divided into four groups: control, PTX, TAA and PTX+TAA treated groups. Rats were administrated TAA together with or without PTX for a week and sacrificed 24 h after the last intragastric administration of PTX. Histopathological analysis was carried out. The liver function, the indices of oxidative stress including malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) in liver tissues, and pro-inflammatory cytokines expressions were examined. The mRNA level of NF-κB p65 in liver was also determined. PTX significantly attenuated TAA-induced liver injury. The serum transaminase and MDA levels were reduced while the levels of SOD and GSH were increased, as compared with the TAA-treated group. PTX also remarkably suppressed the secretions of pro-inflammatory cytokines and the nuclear factor-κB (NF-κB) activation induced by TAA. In addition, the histopathological analysis showed that the range and degree of liver tissue lesions were improved obviously in PTX treated group. Pentoxifylline could ameliorate the effects of thioacetamide-induced acute liver injury in rats by inhibiting oxidative stress, expressions of pro-inflammatory cytokines and NF-κB activation.     

Regulation of delayed-type hypersensitivity V. Suppressor cell memory in antigen-specific suppression of delayed-type hypersensitivity to sheep erythroeytes

Mice primed i. v. with 10⁹ sheep red blood cells (SRBC) produce antigen-specific T suppressor (Ts) cells which inhibit both the induction and the expression of delayed-type hypersensitivity (DTH). These Ts cells are detectable in the spleen and lymph nodes 3–5 days after priming but are largely absent by 6 days. The transient detect-ability of the Ts cells contrasts sharply with the profound antigen-specific suppression which persists in primed donor mice for at least a year. Evidence is presented that this long-term impairment of DTH is maintained, at least in part, by memory Ts cells which are Thy-1⁺, cyclophosphamide-resistant and antigen-specific. Although they appear to be co-induced with the short-lived primary Ts cells and localize initially in the lymphoid organs, they are present in the long-lived circulating pool of T cells and can be adoptively transferred by celomic parabiosis. Memory Ts cells are readily reactivated by lower doses of SRBC which would induce T effector cells rather than Ts cells in naive animals. Reactivated memory Ts cells seem to generate a population of antigen-specific secondary Ts cells which again localizes in the lymphoid organs and can adoptively suppress the induction and expression of DTH to SRBC.     

一氧化氮与利血平致大鼠胃粘膜损伤的关系

目的: 探讨一氧化氮(NO)与利血平致大鼠胃粘膜损伤机制的关系。方法: 从大鼠腹腔内注入利血平复制成胃粘膜损伤模型,并随机分为实验组和对照组。用镉还原加格氏显色法和改良硫代巴比妥酸法分别测定两组大鼠血浆及胃粘膜中NO和丙二醛(MDA)含量,用还原型辅酶Ⅱ组织化学方法结合图像分析对两组大鼠胃壁内一氧化氮合酶(NOS)进行定位、定量研究。结果: 实验组大鼠血浆、胃粘膜中NO含量显著低于对照组(P＜0.01),而其MDA含量则显著高于对照组(P＜0.05,P＜0.01);实验组大鼠胃壁内NOS阳性神经细胞、阳性神经纤维密度及其着色深度均显著低于对照组(P＜0.05,P＜0.01)。结论: 利血平致大鼠胃粘膜损伤的发生可能与大鼠胃壁内NOS阳性神经成分减少,体内NO不足使其对胃粘膜的保护作用减弱有一定关系。     

内源性一氧化氮预防大鼠乙醇性胃粘膜损伤的研究

目的：探讨内源性一氧化氮在大鼠乙醇性胃粘膜损伤时保护胃粘膜作用及机制。方法：大鼠７２ 只,随机分为４ 组,正常对照组,单纯乙醇灌胃（Ｅｔｈ） 组,Ｌ－ 精氨酸＋ 乙醇（Ｌ－ ａｒｇ ＋ Ｅｔｈ） 组,Ｌ－ 硝基精氨酸＋ 乙醇（Ｌ－ ＮＮＡ＋Ｅｔｈ） 组,观察其血浆ＮＯ 含量对胃粘膜的大体及组织学损伤程度、胃粘膜血流量（ｇａｓｔｒｉｃ ｍｕｃｏｓａｌ ｂｌｏｏｄ ｆｌｏｗ ,ＧＭＢＦ） 和胃粘液分泌量的影响。结果：Ｅｔｈ 组血浆ＮＯ 含量,ＧＭＢＦ 和粘液分泌量明显少于对照组（ Ｐ 均＜ ０－０５） ,Ｌ－ ａｒｇ ＋ Ｅｔｈ 组血浆ＮＯ 含量,ＧＭＢＦ 和粘液分泌量明显多于Ｅｔｈ 组（ Ｐ 均＜ ０ ．０５） ,而乙醇对胃粘膜损伤明显减轻（ Ｐ＜ ０－０５） ,Ｌ－ ＮＮＡ ＋ Ｅｔｈ组血浆ＮＯ 含量ＧＭＢＦ 和粘液分泌量明显少于前３ 组（ Ｐ 均＜ ０－０５） ,而胃粘膜损伤程度明显较重（ Ｐ＜ ０－０５） 。结论：内源性ＮＯ 保护胃粘膜对抗乙醇引起的损伤,是通过增加胃粘膜血流量和促进粘液分泌而实现的。