大鼠面神经完全切断后面神经核内OMgp的表达

目的:通过建立大鼠面神经完全切断损伤模型,观察面神经损伤后脑干内OMgp表达的变化。方法:对36只大鼠分别行左侧面神经茎乳孔切断术,于术后1、3、5、7、14、21d取大鼠脑干含面神经核团部分,应用免疫组织化学方法检测面神经核中OMgp的变化及其对面神经元凋亡的影响。结果:OMgp分布于正常SD大鼠面神经各亚核,面神经损伤后OMgp与假手术对照侧相比较均下降,免疫组织化学方法显示5～14d下降明显并显示神经元细胞凋亡增加,图像分析OMgp灰度值与假手术对照侧比较,差异有统计学意义(P0.05)。结论:OMgp对神经网络的重建有重要意义,同时在面神经损伤中发挥重要作用。     

肥大细胞脱颗粒促进外源树突状细胞向引流淋巴结归巢

目的:探讨通过诱导局部肥大细胞脱颗粒促进外源骨髓源性树突状细胞(BM-DC)向淋巴结迁移归巢的方法。方法:采用肥大细胞脱颗粒刺激剂compound 48/80(c48/80)进行C57BL/6小鼠局部皮肤注射,诱导局部组织肥大细胞脱颗粒。将体外培养的荧光微球标记的同系小鼠BM-DC注射入c48/80或生理盐水处理的局部皮肤,48h收集注射部位引流淋巴结细胞进行CD11c荧光抗体染色,流式细胞术测定外源回输的BM-DC的迁移效果。结果:c48/80注射小鼠皮肤后可有效地促进局部组织肥大细胞脱颗粒,c48/80处理侧局部引流淋巴结中外源BM-DC迁移细胞总数和淋巴结细胞总数较对照侧均明显增多,增多比例分别为67%±43%和55%±43%(P0.05)。结论:通过诱导局部皮肤肥大细胞脱颗粒,可促进外源BM-DC向淋巴结归巢。     

Changes in expression of prosaposin in the rat facial nerve nucleus after facial nerve transection

Prosaposin is the precursor of saposins A, B, C and D, which are activators of sphingolipid hydrolases. In addition, unprocessed prosaposin functions as a neurotrophic factor in the central and peripheral nervous systems by acting to prevent neuronal apoptosis, to elongate neurites and to facilitate myelination. In this study, the expression pattern of prosaposin in the facial nerve nucleus after facial nerve transection was examined by immunohistochemistry and in situ hybridization. Prosaposin immunoreactivity in the neurons on the operated side facial nerve nucleus showed a biphasic pattern: it was significantly increased on day 3 after transection, decreased dramatically on day 7, started to increase gradually on day 14 and reached another peak on day 21 after transection. Significant increases in the levels of prosaposin mRNA were identified in the neurons on the operated side, suggesting that prosaposin was synthesized vigorously by the neurons themselves in the case of facial nerve transection. The diverse changes in prosaposin immunoreactivity during the process of facial nerve regeneration may reflect the diverse neurotrophic activities of prosaposin in facial motoneurons.     

树突状细胞引流淋巴结归巢的研究进展

树突状细胞(dendritic cells,DCs)是目前已知的体内功能最强的专职性抗原提呈细胞(professional antigen-present-ing cells,pAPC),在引发和调节机体的免疫反应中起着重要作用。树突状细胞最重要的功能是摄取、加工处理、提呈抗原,并刺激初始T细胞(naive T cells)活化、增殖,从而激发机体的免疫应答。DCs这一功能是在体内迁移过程中发挥的,其中DCs归巢至引流淋巴结被认为是激发免疫应答的关键步骤之一。本文将就近年来DCs归巢至引流淋巴结的研究进展作一综述。     

树突状细胞向淋巴结归巢的研究进展

树突状细胞（DC）作为专职抗原递呈细胞在诱导机体产生抗肿瘤免疫应答过程中发挥重要作用。以此为基础制备的DC肿瘤疫苗在抗肿瘤免疫治疗中显示出一定的疗效。体外回输DC迁移归巢至局部引流淋巴结是激发特异性免疫应答的关键步骤,归巢DC的数目直接影响免疫应答的强度。了解DC体内归巢至淋巴结的机制,促进DC向淋巴结迁移对于提高DC疫苗的抗肿瘤效果具有重要意义。趋化因子和相应受体、黏附分子、基质金属蛋白酶和脂类介质等多种因素共同调控DC向淋巴结归巢,其中CCR7及其配体CCL19和CCL21是一组最受关注的因子。     

T cell memory in the injured facial motor nucleus: relation to functional recovery following facial nerve crush

T cells have the ability to mount a memory response to a previously encountered antigen such that re-exposure to the antigen results in a response that is greater in magnitude and function. Following facial nerve transection, T cells have been shown to traffic to injured motor neurons in the facial motor nucleus (FMN) and may have the ability to promote neuronal survival and functional recovery. Previously, we demonstrated that early exposure to neuronal injury on one side of the brain during young adulthood elicited a T cell response that was greater in magnitude following exposure to the same form of injury on the contralateral side later in adulthood. Whether the T cell memory response to neuronal injury influenced functional recovery following nerve crush injury was unknown. In the current study, we tested the hypotheses that (1) transection of the right facial nerve in sensitized mice would result in faster recovery of the whisker response when the contralateral facial nerve is crushed 10 weeks later, and (2) the early recovery would be associated with an increase in the magnitude of the T cell response in the contralateral FMN following crush injury in sensitized mice. The onset of modest recovery in sensitized mice occurred between 3 and 5 days following crush injury of the contralateral facial nerve, approximately 1.5 days earlier than naïve mice, and was associated with more than a two-fold increase in the magnitude of the T cell response in the contralateral FMN following crush injury. There was no difference between groups in the number of days to full recovery. Further study of how T cell memory influences neuroregeneration may have important implications for translational research.     

Expression patterns in alternative splicing forms of prosaposin mRNA in the rat facial nerve nucleus after facial nerve transection

Prosaposin acts as a neurotrophic factor, in addition to its role as the precursor protein for saposins A, B, C, and D, which are activators for specific sphingolipid hydrolases in lysosomes. In rats, the prosaposin gene generates two alternative splicing forms of mRNA: Pro+9 containing a 9-base insertion and Pro+0 without. The expression of these mRNAs changes after brain injury. We examined the expression patterns of the alternative splicing forms of prosaposin mRNA in the rat facial nerve nucleus for 52 days following facial nerve transection. Pro+0 mRNA increased within 3 days of transection, peaked after 5-10 days, and remained significantly elevated for 21 days. In contrast, the expression of Pro+9 mRNA was constant throughout the regenerative period. Prosaposin mRNA expression increased not only in facial motoneurons, but also in microglia during facial nerve regeneration. Our findings indicate that the saposin B domain of prosaposin, which is the domain affected by alternative splicing, plays an important role in both neurons and microglia during neuroregeneration.     

In vivo regulation of the cytolytic T cell response to hapten-altered self: suppressor T cells induced in the regional lymph nodes by exposure to syngeneic spleen cells

During the course of examining the in vivo development of the cytotoxic T lymphocyte (CTL) response to hapten-modified self antigens in mice, we have observed that it can be abrogated through prior exposure of the host's regional lymph nodes (LN) to normal syngeneic spleen cells (NSC). Suppression appeared to be antigen nonspecific and was best seen when animals were injected in the footpads with NSC at least 72 h before sensitization for CTL. The ability to prevent the development of the CTL response was restricted primarily to syngeneic splenic T and B cells since syngeneic thymocytes stimulated only partial suppression and syngeneic LN cells, as well as hapten-coupled syngeneic spleen cells, did not at all. Suppression appeared to be a local phenomenon in that the NSC induced transferable suppressor T cells to appear in the popliteal LN draining the footpads but not in spleens. In addition, animals splenectomized prior to injections of NSC showed abrogated CTL responses equivalent to sham-splenectomized animals indicating that the spleen does not contribute to the mechanism of suppression. Finally, when only one footpad was injected with NSC, suppression was seen in the draining popliteal node and not in the contralateral node. Taken together, the evidence suggests that the source of the suppression and the suppressor T cells may be attributed to an in vivo syngeneic mixed lymphocyte reaction occurring between responder cells of the draining LN and injected stimulator spleen cells.     

Role of B cells as antigen-presenting cells in vivo revisited: antigen-specific B cells are essential for T cell expansion in lymph nodes and for systemic T cell responses to low antigen concentrations.

Studies in B cell-deficient mice generated by continuous injection of anti-mu antibodies (muSM) showed that T cell priming in lymph nodes was dependent on antigen presentation by B cells. This concept has recently become controversial since a wide range, from complete deficiency to near normal T cell responses, was reported in studies carried out with B cell-deficient mice generated by gene disruption (muMT). In this study we show that in the absence of B cells, T cell responses are greatly reduced in all the available muMT mouse strains although responses in muMT of the C57BL/6 background (which were used for most studies with muMT) were much more variable and could reach up to 42% of control. In contrast, T cell responses in muMT --> F(1) bone marrow chimeras which have the same phenotype as muMT were totally impaired, suggesting a principle difference between mice developing without B cells (muMT mice) and muSM which are made B cell deficient only after birth. Normal T cell priming was completely restored by reconstitution of muMT and muMT --> F(1) mice with syngeneic B cells. Interestingly, only B cell populations containing antigen-specific B cells were capable of reconstituting T cell responses. Monoclonal B cells taken from Ig transgenic mice could not reconstitute responses to an irrelevant antigen. We also found that B cells were also required for systemic T cell priming when antigen concentrations were limiting but were not required for priming (for T cell help) when mice were immunized with a high antigen dose.     

Mouse autoreactive gamma/delta T cells. I. Functional properties of autoreactive T cell hybridomas.

A minor population of dendritic epidermal T cells (DETC) express the V gamma 1.1C gamma 4V delta 6 T cell receptor and T cell clones and hybridomas derived from this subset constitutively secrete cytokines in culture secondary to recognition of an autoantigen. Activation of these autoreactive cells requires the use of the vitronection receptor (VNR) as an accessory molecule which interacts with the Arg-Gly-Asp-Ser (RGDS) sequence of extracellular matrix (ECM) proteins. We have compared the functional properties of C gamma 4+ hybridomas derived from newborn thymocytes and from adult spleen with the DETC hybridomas/lines in terms of their ability to secrete cytokines spontaneously and for the use of the VNR as an accessory molecule. Almost all the C gamma 4+ thymocyte hybridomas secreted cytokines spontaneously and in the majority of lines the most prominent cytokine secreted was granulocyte-monocyte colony-stimulating factor. In contrast, none of the four splenic C gamma 4+ hybridomas secreted cytokines spontaneously although all were capable of cytokine production following activation via the T cell receptor. Although the thymocyte hybridomas did not grow as adherent cell lines in culture, constitutive cytokine production required engagement of the VNR by its ligand in ECM proteins. In all cases, cytokine production could be inhibited by an anti-VNR monoclonal antibody as well as by soluble RGDS. The strong correlation of functional and molecular properties between thymocyte C gamma 4+ hybridomas and C gamma 4+ DETC suggests that the C gamma 4+ DETC may be of thymic origin and that cells with potential for autoreactivity residing in the thymus at birth may populate other peripheral locations in the mouse. The data also support the concept that the VNR, and possibly other integrins, play a role as accessory elements for autoreactive cells and may be essential for the regulation of such activity.     

The potential importance of HIV-induction of lymphocyte homing to lymph nodes.

The mechanism by which HIV causes depletion of CD4 lymphocytes remains unknown. Recent studies have demonstrated that HIV binding to resting CD4 lymphocytes causes them to home from the blood into lymph node, and during the homing process, they are induced into apoptosis only to secondary signals through the homing receptors. If this is the principal mechanism of CD4 cell depletion, it can explain many of the events known to occur in HIV-infected individual.     

Role of the H-2 complex in the homing affinity of injected lymphoid cells to the host's lymph nodes.

The role of H-2 and non-H-2 gene products was studied in a model of non-immune cell-cell interactions which underlie the homing affinity to lymph nodes of injected 51Cr-labelled lymph node cells. The effect of various donor-recipient combinations was tested by comparing the allogeneic/syngeneic ratio of radioactivity recovered from the lymph nodes. The homing affinity was reduced to about 50% when the donor-recipient incompatibility extended over the whole H-2 chromosome. When confined to a single region (H-2K, I or D) H-2 incompatibility caused no significant allogeneic inhibition of the homing affinity. The cumulative effect of two partial incompatibilities (K + I or D + I) was, however, reflected in a significant allogeneic inhibition. Non-H-2 incompatibilities had, as a rule, a weak effect; the non-H-2 gene products may not be directly involved in the cell interactions under test.     

Frequency of circulating autoreactive T cells committed to myelin determinants in relapsing-remitting multiple sclerosis patients

Some organ-transplanted patients achieve a state of "operational tolerance" (OT) in which graft function is maintained after the complete withdrawal of immunosuppressive drugs. We used a gene panel of regulatory/inflammatory molecules (FOXP3, GATA3, IL10, TGFB1, TGFBR1/ TBX21, TNF and IFNG) to investigate the gene expression profile in peripheral blood mononuclear cells of renal-transplanted individuals experiencing OT compared to transplanted individuals not displaying OT and healthy individuals (HI). OT subjects showed a predominant regulatory (REG) profile with higher gene expression of GATA3, FOXP3, TGFB1 and TGFB receptor 1 compared to the other groups. This predominant REG gene expression profile displayed stability over time. The significant GATA3 gene and protein expressions in OT individuals suggest that a Th2 deviation may be a relevant pathway to OT. Moreover, the capacity of the REG/INFLAMMA gene panel to discriminate OT by peripheral blood analysis indicates that this state has systemic repercussions.     

Ly6C supports preferential homing of central memory CD8+ T cells into lymph nodes

Ly6C is a murine cell‐surface antigen expressed by plasma cells, subsets of myeloid cells and many T cells, including memory T cells. We previously documented that Ly6C crosslinking induces LFA‐1 clustering on naïve CD8⁺ T cells. Here, we show that in vitro and in vivo differentiation of naïve CD8⁺ T cells into central (Tcm) but not effector (Tem) memory T cells enhances Ly6C expression, and its crosslinking induces strong LFA‐1 clustering on Tcm. Blocking Ly6C function inhibits in vivo Tcm homing to LNs as efficiently as blocking L ‐selectin but it does not potentiate the inhibition provided by blocking either L ‐selectin or LFA‐1 function. Thus, Ly6C, L ‐selectin and LFA‐1 all appear to be part of a common homing pathway. In vitro, Ly6C crosslinking enhances Tcm adherence to ICAM‐1 in the presence of CCL21. In summary, Tcm homing involves Ly6C, in addition to L ‐selectin and LFA‐1, and appears to potentiate firm adhesion of Tcm to ICAM‐1 in synergy with a chemokine. We propose that Ly6C augments Tcm compartmentalization into LNs during their homing.     

Cellular orchestration of T cell priming in lymph nodes

Progress made in visualizing T cell responses in vivo and at the single cell level has revealed an unexpected level of complexity in the orchestration of T cell activation in lymph nodes. The choreography that leads to the initiation of a T cell response involves multiple cellular actors, and is intrinsically influenced by their motility and their mode of cell-cell interactions. Recent studies have begun to depict the cellular orchestration of T cell priming and to analyze the way it could influence the outcome of T cell responses.     

Differences in the tissue-specific homing of {alpha}{beta} and {gamma}{delta} T cells to gut and peripheral lymph nodes

Tissue-selective streaming of T cells is considered to be acritical element in the integration of normal immune responsesin intact animals. The results presented in this paper showthat while there were major subsets of gut-homing T cells presentin intestinal lymph, there were considerable differences inthe tissue troplsm of T cell populations circulating in lymphdraining gut and peripheral lymph nodes. Thus, while CD4⁺ cellsreturned preferentially to their tissue of origin, y8 T cellsshowed a strong migratory preference for peripheral lymph nodesregardless of their tissue of origin. In contrast, althougha population of gut-homing CD8⁺ cells was present in Heal lymph,CD8⁺ T cells from peripheral lymph nodes homed equally wellto gut and lymph nodes. There were also considerable differencesin the expression of L-selectln on T cells circulating in thetwo compartments. L-selectin was down-regulated on ßT cells present in Meal lymph but not on T cells which expressedthe highest levels of L-selectin of all T cell subsets. It issuggested that gut-homing ß T cells which have down-regulatedL-selectin are formed in the gut-associated lympnoid tissuesin response to gut antigens while the migratory properties of T cells are ontogenetically determined, independent of antigen.     

Regulated release of nitric oxide by nonhematopoietic stroma controls expansion of the activated T cell pool in lymph nodes

Fibroblastic reticular cells (FRCs) and lymphatic endothelial cells (LECs) are nonhematopoietic stromal cells of lymphoid organs. They influence the migration and homeostasis of naive T cells; however, their influence on activated T cells remains undescribed. Here we report that FRCs and LECs inhibited T cell proliferation through a tightly regulated mechanism dependent on nitric oxide synthase 2 (NOS2). Expression of NOS2 and production of nitric oxide paralleled the activation of T cells and required a tripartite synergism of interferon-γ, tumor necrosis factor and direct contact with activated T cells. Notably, in vivo expression of NOS2 by FRCs and LECs regulated the size of the activated T cell pool. Our study elucidates an as-yet-unrecognized role for the lymph node stromal niche in controlling T cell responses.     

Bronchial carcinoma and its regional lymph nodes in relation to immunological functions.

Two hundred and fifty lymph nodes from 100 patients with lung carcinoma and the same number of regional nodes from 119 patients with gastric ulcer were histologically evaluated by the standardized reporting system of COTTIER et al. Special attention was focused on the immunological reactions in these lymph nodes. Histologic features suggesting actively functioning humoral and cell-mediated immune reactions were encountered more frequently in the nodes of the control series. The significance of the histologic findings is discussed and it is concluded that there is some degree of derangement of both humoral and cell-mediated immune responses in the lymph nodes draining lung carcinoma. The applicability of the reporting system used is emphasized.