受体淋巴细胞向小肠移植物相关淋巴组织迁移的实验研究

目的：动态分析移植小肠各淋巴组织内供、受体淋巴细胞的表型及免疫状态，以推断其在小肠移植排斥反应中的作用。 方法： 小鼠小肠移植后2、4、6 d，观测移植物排斥病理形态变化，流式细胞术分析移植物肠系膜淋巴结（MLN）、派氏结（PP）、粘膜上皮细胞间淋巴组织（IEL）与固有层淋巴组织（LPL）中淋巴细胞中供、受体淋巴细胞的比例及激活状态。 结果:在移植后6 d，组织学观测到移植物开始出现排斥征象；移植后2、4 d，移植肠MLN、PP内受体来源的淋巴细胞迅速取代供体细胞，而移植肠IEL与LPL内受体来源的淋巴细胞比例增加速度略慢，但在移植后6 d也基本取代供体细胞；在移植后4 d，受体来源的T细胞表达激活分子CD69与CD25的比例达到89.8%±3.4％和84.5%±10.2％，显著高于供体T细胞与受体自身肠道中的T细胞。 结论:移植小肠内的淋巴组织在移植后早期即被受体来源的淋巴细胞迅速取代并激活，抑制这一过程可应用于缓解排斥反应。     

B and also T lymphocytes migrate via gut lymph to all lymphoid organs and the gut wall,but only IgA+ cells accumulate in the lamina propria of the intestinal mucosa

In pigs the lymphocytes emigrating from the intestinal wall were collected by cannulating the lymphatics, labeled in vitro using a fluorescent dye and retransfused. The injection of 6.6 ± 4.2 × 10⁸ cells resulted in a labeling index between 1.5 % in intestinal lymph, 0.2 % in the spleen and lymph nodes, ∼ 0.1 % in the intestinal lamina propria and 0.003 % in intraepithelial lymphocytes. About 25 % of the injected cells were present in the blood and 1 % was recovered in the lymph. T cells were found in similar proportions in the injected and the recovered cells in the organs (70 – 80 %). The proportion of IgA⁺ cells among the immigrated cells in the intestinal lamina propria ranged from 5 to 8 %, which in absolute numbers was up to 60 % of the injected IgA⁺ cells. T and IgM⁺ cells did not show a higher accumulation in any organ. These experiments in conventional, unrestrained animals revealed that (1) T cells immigrate into the intestinal lamina propria, (2) preferential migration of IgA⁺ cells from gut lymph to the intestinal lamina propria is obvious under in vivo conditions and (3) the immigrated IgA⁺ cells represent a very small population which is difficult to detect when analyzed in relative numbers.     

Reactive murine lymph nodes uniquely permit parenchymal access for T cells that enter via the afferent lymphatics

Whereas naïve T cells access the lymph nodes predominantly via the high endothelial venules, their effector counterparts can also enter via the afferent lymphatics. It is unclear if such cells are confined to the lymphatic spaces during their transit through the lymph node or whether they can access the lymphocyte‐ and dendritic cell‐rich parenchyma with its potentially stimulatory environment. We used a flank HSV inoculation model that featured neuronal‐mediated movement of virus to distinct areas of skin to study the lymphatic‐mediated transit of activated T cells between different skin‐draining lymph nodes. These experiments showed that activated T cells released from the brachial lymph node, draining the primary site of inoculation, entered the downstream axillary lymph node. These activated T cells accessed the subcapsular areas of the axillary lymph node via lymphatic vessels exiting the upstream brachial node regardless of whether the former drained skin that was associated with active infection. However, T cells remained within the sinusoidal network of the axillary lymph node unless it was directly associated with peripheral infection. Thus, activated T cells that enter a given lymph node using the afferent lymphatics do not have automatic access to the parenchyma unless it is a reactive node involved with peripheral inflammation or infection. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Interleukin-15 preferentially promotes the growth of intestinal intraepithelial lymphocytes bearing γδ T cell receptor in mice

Several cytokines including stem cell factor (SCF) and interleukin (IL)-7 are known to be required for development of γδ T cell receptor (TCR) intestinal intraepithelial lymphocytes (i-IEL) in mice. We show here the effects of IL-15 on the proliferation and maintenance of murine γδ i-IEL in vitro. γδ i-IEL constitutively expressed a high level of IL-15 receptor α mRNA and proliferated in response to IL-15 more vigorously than αβ i-IEL. Vγ/δ repertoire analysis revealed that IL-15, like IL-2, induced polyclonal expansion of γδ i-IEL, whereas γδ i-IEL responding to IL-7 showed a Vγ/δ repertoire skewed towards Vγ1/Vδ4, Vδ5. IL-15 efficiently prevented γδ i-IEL from apoptosis induced by growth factor deprivation. This rescue was accompanied by up-regulation of Bcl-2 expression. These results suggest that IL-15 plays important roles in proliferation and maintenance of γδ i-IEL.     

Host intestinal intraepithelial γδ T lymphocytes present during acute graft-versus-host disease in mice may contribute to the development of enteropathy

We reported that T cell receptor (TcR) γδ intestinal intraepithelial lymphocytes (i-IEL) of host origin increased transiently, then decreased drastically at the early stage of non-irradiated acute graft-versus-host disease (GVHD) in mice. We investigated the role of the TcR γδ i-IEL of host origin in the pathogenesis of the intestinal lesions that occur during acute GVHD. The acute GVHD was induced in mice which had been depleted of TcR γδ by in vivo administration of hamster monoclonal antibody (mAb) against TcR γδ. Although the degree of splenomegaly after the induction of acute GVHD in mice treated with anti-TcR γδ mAb was similar to that in control mice treated with hamster anti-2,4,6-trinitrophenyl mAb, infiltration of donor-derived T cells into the epithelium, and mitosis and apoptosis of crypt cells in the intestinal mucosa were dramatically suppressed in these mice. This suggest that host TcR γδ T cells in i-IEL contribute to the development of enteropathy in acute GVHD in mice.     

Progress in the use of swine in developmental immunology of B and T lymphocytes

The adaptive immune system of higher vertebrates is believed to have evolved to counter the ability of pathogens to avoid expulsion because their high rate of germline mutations. Vertebrates developed this adaptive immune response through the evolution of lymphocytes capable of somatic generation of a diverse repertoire of their antigenic receptors without the need to increase the frequency of germline mutation. The focus of our research and this article is on the ontogenetic development of the lymphocytes, and the repertoires they generate in swine. Several features are discussed including (a) the “closed” porcine placenta means that de novo fetal development can be studied for 114 days without passive influence from the mother, (b) newborn piglets are precocial permitting them to be reared without their mothers in germ-free isolators, (c) swine are members of the γδ−high group of mammals and thus provides a greater opportunity to characterize the role of γδ T cells and (d) because swine have a simplified variable heavy and light chain genome they offer a convenient system to study antibody repertoire development.     

Proliferating macrophages, dendritic cells, natural killer cells, T and B lymphocytes in the middle ear and Eustachian tube mucosa during experimental acute otitis media in the rat.

Although many studies focus on the increase of immunocompetent cells within the middle ear mucosa during acute otitis media it is poorly understood how this increase is mediated. The differentiation between two possible causes, i.e. immigration and local proliferation, would help to better understand the pathophysiology of this disease. Therefore, the number of proliferating macrophages, dendritic cells, natural killer cells and T and B lymphocytes was studied during acute otitis media in the rat middle ear mucosa (ME mucosa) and Eustachian tube mucosa (ET mucosa) by labelling proliferating leucocytes with the DNA precursor bromodeoxyuridine (BrdU). By removing the middle ear and Eustachian tube 24 h after BrdU injection, the contribution of immigrated newly formed cells was estimated. At this timepoint, many leucocytes in the ME and ET mucosa had incorporated BrdU (between 15 and 25% within the subsets). By analysing these tissues one hour after BrdU injection, the local proliferation rate was determined (between 2 and 9% within the subsets). Thus, the inflamed ME and ET mucosa are the destination of immunocompetent cells and, as our data show, the inflamed microenvironment supports local proliferation of immunocompetent cells.