Anti-CD2 and anti-CD3 induced T cell cytotoxicity of human intraepithelial and lamina propria lymphocytes.

The effector function of immunocompetent cells in the gut mucosa has not yet been defined. The cytotoxic function of these cells might be important in the normal immune response and could be relevant to the mucosal damage seen in inflammatory conditions. The cytotoxic function of isolated intraepithelial and lamina propria mononuclear cells in six and 18 hour assays after the addition of various stimuli that interact with the human leukocyte antigens CD2 and CD3 on the mucosal effector cells was investigated. T cell phenotypes were determined using CD4, CD8, and HML1 to characterise cells of the appropriate compartments. Anti-CD3 and phytohaemagglutinin can induce toxic activity of lamina propria lymphocytes in most individuals after six hours and in all individuals after 18 hours. Anti-CD2, anti-CD3, and phytohaemagglutinin are similarly effective at triggering lamina propria lymphocytes. Intraepithelial lymphocytes contain predominantly CD8 and HML1 positive T cells, differentiating phenotypically intraepithelial lymphocytes from lamina propria lymphocytes. Intraepithelial lymphocytes are not cytotoxic at six hours, but have a toxic function comparable with lamina propria lymphocytes after 18 hours with all three triggers. Intraepithelial lymphocytes from inflamed mucosa (Crohn's disease and diverticulitis) mediate significantly reduced cytotoxicity in vitro compared with normal mucosa, whereas lamina propria lymphocyte toxicity is not different. Reduced numbers of cytotoxic cells and reduced reactivity to the trigger substances used after in vivo activation or cold target inhibition could explain the observed differences between intraepithelial lymphocytes from inflamed and uninflamed mucosa. Changes in cell mediated cytotoxicity of intraepithelial lymphocytes and lamina propria lymphocytes may be involved in the mucosal damage in these inflammatory conditions.     

Changes in mesenteric lymph node T cell phenotype and B and T cell homing properties after murine AIDS infection

We studied MLN (mesenteric lymph nodes) T cell phenotype and MLN T and B cells homing properties after murine AIDS (acquired immunodeficiency syndrome) infection. Our results showed an increase in the percentage of CD4+ cells expressing CD44, CD54 and LPAM-1. There was also a decrease in the proportion of CD8+ cells but an increase in the percentage of CD8+ CD54+ cells. An increased proportion of CD11b+ (Mac1) cells suggested the recruitment of macrophages. Murine AIDS MLN cells labeled with 125I-UDR migrated back to the MLN but did not preferentially migrate to the ILP (intestinal lamina propria). Simultaneous staining for BRDU and IgA confirmed the inability of murine AIDS MLN cells to home to the ILP. These data indicate that murine AIDS infection altered the mucosal immune system while modifying MLN T cell phenotype and MLN T and B cells migratory properties.     

Intestinal colonization with Candida albicans and mucosal immunity

AIM: To observe the relationship between intestinal lumen colonization with Candida albicans and mucosal secretory IgA (sIgA).METHODS: A total of 82 specific-pathogen-free mice were divided randomly into control and colonization groups. After Candida albicans were inoculated into specific-pathogen-free mice, the number of Candida albicans adhering to cecum and mucosal membrane was counted. The lymphocyte proliferation in Peyer‘s patch and in lamina propria was shown by BrdU incorporation, while mucosal sIgA (surface membrane) isotype switch in Peyer‘s patch was investigated. IgA plasma cells in lamina propria were observed by immunohistochemical staining. Specific IgA antibodies to Candida albicans were measured with ELISA.RESULTS: From d 3 to d 14 after Candida albicansgavaging to mice, the number of Candida albicans colonizing in lumen and adhering to mucosal membrane was sharply reduced.Candida albicans translocation to mesenteric lymph nodes occurred at early time points following gavage administration and disappeared at later time points. Meanwhile, the content of specific IgA was increased obviously. Proliferation and differentiation of lymphocytes in lamina propria were also increased.CONCLUSION: Lymphocytes in lamina propria play an important role in intestinal mucosal immunity of specific-pathogen-free mice when they are first inoculated with Candida albicans. The decreasing number of Candida albicans in intestine is related to the increased level of specific IgA antibodies in the intestinal mucus.     

Immunological study of the rectal mucosa of men with and without human immunodeficiency virus infection.

Biopsies of rectal mucosa were taken from 81 men and stained using cytochemical methods for B and T lymphocytes, T cell subsets, immunoglobulin containing plasma cells and mucosal mast cells. The patients studied included human immunodeficiency virus (HIV) infected and non-infected heterosexual and homosexual men, and homosexual men with rectal gonorrhoea. There were increased numbers of T lymphocytes in the lamina propria of the rectum in HIV infected individuals regardless of whether the infection had been acquired through anal intercourse or intravenous drug use. This increase resulted from a marked increase in the numbers of CD8+ suppressor T cells, there also being a reduction in the numbers of CD4+ helper T cells. In non-HIV infected men with rectal gonorrhoea there were increased numbers of CD8+ T cells but no significant difference in numbers of CD4+ cells. No difference was seen in numbers of CD4+ cells. No difference was seen in numbers of immunoglobulin containing plasma cells or mucosal mast cells between HIV infected and non-infected men.     

Alterations of intestinal immune function and regulatory effects of L-arginine in experimental severe acute pancreatitis rats

ABM: To discuss the changes of intestinal mucosal immune function in rats with experimental severe acute pancreatitis (SAP) and the regulatory effect of L-arginine. METHODS: Male adult Wistar rats were randomly divided into pancreatitis group, sham-operation group, and L-arginine treatment group. Animals were killed at 24, 48, and 72 h after SAP models were developed and specimens were harvested. Endotoxin concentration in portal vein was determined by limulus endotoxin analysis kit. CD3+, CD4+, CD8+ T lymphocytes in intestinal mucosal lamina propria were examined by immunohistochemistry. Secretory immunoglobulin A (SIgA) in cecum feces was examined by radioimmunoassay. RESULTS: Compared to the control group, plasma endotoxin concentration in the portal vein increased, percentage of CD3+ and CD4+ T lymphocyte subsets in the end of intestinal mucosal lamina propria reduced significantly, CD4+/CD8+ ratio decreased, and SIgA concentrations in cecum feces reduced at 24, 48, and 72 h after SAP developed. Compared to SAP group, the L-arginine treatment group had a lower level of plasma endotoxin concentration in the portal vein, a higher CD3+ and CD4+ T lymphocyte percentage in the end of intestinal mucosal lamina propria, an increased ratio of CD4+/CD8+ and a higher SIgA concentration in cecum feces. CONCLUSION: Intestinal immune suppression occurs in the early stage of SAP rats, which may be the main reason for bacterial and endotoxin translocation. L-arginine can improve the intestinal immunity and reduce bacterial and endotoxin translocation in SAP rats.     

Below the belt: new insights into potential complications of HIV-1/schistosome coinfections

PURPOSE OF REVIEW: Areas of the world with high endemnicity for helminth parasites overlap with those regions that have a seemingly disproportionate prevalence of HIV/AIDS. This has fueled speculation that potential pathological interactions between these infectious agents may accelerate disease progression. The proximity of many helminth infections to gastrointestinal mucosal sites combined with the recent discovery that acute HIV-1 infection causes early and massive depletion of CD4+ T cells in the gut furthers the potential pathological significance of co-infection. In this review, the 'gut wrenching' consequences of schistosome infection on HIV disease progression that may ensue during coinfection are considered. RECENT FINDINGS: Massive depletion of CD4+ T cells in the gut during acute HIV-1 infection suggests that in addition to the administration of highly active antiretroviral therapy, limiting viral infection of susceptible cells in the gut after initial exposure may offer the best opportunity for slowing disease progression. In addition to memory T cells, mast cells, which are present in the intestinal lamina propria and upregulated in the gut during schistosome infection, have been recently described as an inducible reservoir of persistent HIV-1 infection. SUMMARY: Schistosome infections create immune environments that may accelerate HIV disease progression. Their impact on highly active antiretroviral therapy should be considered.     

RNA干扰抑制IL-23表达对感染后内脏高敏感小鼠肠黏膜固有层DC活化Th17细胞功能的影响

背景：前期研究发现感染后内脏高敏感小鼠肠黏膜固有层树突细胞（DC）诱导活化Th17细胞与肠道感染消退后肠黏膜免疫系统的持续激活有关。推测DC可能系通过分泌白细胞介素-23（IL-23）活化Th17细胞。目的：应用RNA干扰技术抑制DC分泌IL-23,探讨感染后内脏高敏感小鼠肠黏膜固有层DC活化Th17细胞的机制。方法：建立旋毛虫感染后内脏高敏感小鼠模型,以免疫磁珠分选肠黏膜固有层DC和脾脏CD4＋T细胞。构建、鉴定小鼠IL-23小发夹RNA（shRNA）干扰质粒,以脂质体法转染DC（A组）以抑制IL-23表达,同时设置转染空脂质体的DC（B组）和转染无关序列shRNA干扰质粒的DC（C组）作为对照。各组DC与CD4＋T细胞共培养120 h,以单独培养的CD4＋T细胞（D组）作为对照。以ELISA方法检测DC转染前后培养上清液中的IL-23水平,以及DC与CD4＋T细胞共培养上清液和CD4＋T细胞单独培养上清液中的IL-17水平。结果：A组DC培养上清液中的IL-23水平较转染前显著降低（P〈0.05）,B、C两组转染前后IL-23水平无明显变化。A、B、C组DC与CD4＋T细胞共培养上清液中的IL-17水平均较D组显著增高（P〈0.05）,其中A组显著低于B、C两组（P〈0.05）,B、C组间差异无统计学意义。结论：感染后内脏高敏感小鼠肠黏膜固有层DC可能通过分泌IL-23活化Th17细胞,参与维持肠道感染消退后肠黏膜免疫系统的持续激活。     

感染后内脏高敏感小鼠肠道黏膜固有层树突细胞对CD4~+T 细胞的作用

背景: 多项证据提示感染后肠易激综合征(PI-IBS)患者的肠道黏膜中存在T细胞介导的低度炎症。树突细胞(DC)是肠道黏膜免疫系统中最重要的抗原呈递细胞,目前关于DC在PI-IBS中作用的报道尚少。目的: 研究肠道黏膜固有层DC在急性肠道感染的不同阶段对CD4~+ T细胞的影响,探讨DC在肠道感染消退后维持肠道黏膜免疫系统持续激活中的作用。方法: 建立旋毛虫感染后内脏高敏感小鼠模型以模拟人类PI-IBS。肠道黏膜固有层DC与脾脏CD4~+T细胞于体外共培养120h,ELISA法检测细胞培养上清液中Th17、Th2、Th1相关细胞因子IL-17、IL-4、IFN-γ水平。结果: 与单独培养相比,CD4~+T细胞与DC共培养后,感染后8周组IL-17水平增加值明显高于对照组(P=0.001)和感染后2周组(P=0.279):感染后2周组IL-4水平增加值明显高于对照组(P=0.041)和感染后8周组(P=0.204);三组间IFN-γ水平增加值差异均无统计学意义。结论: 感染后内脏高敏感小鼠肠道黏膜固有层DC诱导CD4~+T细胞分化为Th17细胞并使之活化可能是肠道感染消退后维持肠道黏膜免疫系统持续激活的主要机制。     

Avian coccidiosis: changes in intestinal lymphocyte populations associated with the development of immunity to Eimeria maxima

The effect of infection and subsequent challenge with Eimeria maxima on the populations of lymphocytes in the small intestine of Light Sussex chickens was assessed by immunohistochemistry. T cells were characterized for CD3, CD4, CD8, TCR1 (γδ heterodimer) or TCR2 (αβ₁ heterodimer) markers, and B cells for the expression of IgM, IgA andlgG. After a primary inoculum there were, in both the epithelium and the lamina propria, two distinct increases in the numbers of T lymphocytes. The first peaked on days 3–5 and the second, greater influx, on day 11 after infection. CD4+ and CD8+ cells were represented in both peaks but, whereas CD4+ cells were found almost exclusively in the lamina propria, CD8+ cells were present in both sites. The area staining positive for CD8+ cells was somewhat greater than the value obtained for CD4+ cells. In the epithelium there was an early, small increase in TCR1+-staining, followed by a larger rise to the second peak, at which time there was also an increase in the lamina propria. Staining for TCR2+ cells followed the same pattern with a reversed distribution between epithelium and lamina propria. Changes after challenge were minimal and confined to the epithelium. The most notable changes in the expression of immunoglobulins were, in the lamina propria, a biphasic increase in the amount ofIgM+-staining in the course of primary infection (corresponding approximately to that of the T cells), and in IgA + cells shortly after challenge.     

Mucosal T-cell function.

Lymphocytes in the intestinal lamina propria probably differ from lymphocyte populations in the circulation or in other tissue sites in a number of ways. First, lamina propria lymphocytes are phenotypically distinct in that few of these cells normally express the Leu-8 or CD45RA antigens. The presence of these molecules on CD4 T cells correlates with suppressor and suppressor-inducer function, and therefore the majority of CD4 T cells in the intestinal lamina propria have the phenotype associated with high helper activity. A substantial proportion of lamina propria lymphocytes also have evidence of activation, based on expression of the IL-2R alpha chain and HLA-DR molecules. Lymphocytes in the intestinal lamina propria are different in their potential for expression of lymphokine gene products, because activated cells from the lamina propria have high expression of mRNA for IL-2, IL-4, IL-5, and IFN-gamma in comparison to circulating lymphocytes. Mesenteric lymph node T cells also differ from circulating lymphocytes in their high expression of IL-4 and IL-5 mRNA. A further difference between mesenteric lymph node and lamina propria T cells is that the former can proliferate in response to IL-4, whereas the latter cannot. These phenotypic and mRNA differences of lamina propria lymphocytes also correlate well with their high helper activity in vitro for immunoglobulin synthesis in the pokeweed mitogen system. T cells with the potential for cytolytic activity are present in the intestinal lamina propria, although there is no definitive evidence that they are cytolytically active under physiologic or pathologic conditions. Finally, in a model system of intestinal inflammation, lymphogranuloma venereum in nonhuman primates, lamina propria T cells at the site of inflammation were unable to respond to specific antigens with proliferation but did respond with high helper activity. These observations are all consistent with the conclusion that T cells in the lamina propria are pleomorphic but are highly enriched for subpopulations of activated memory cells that are geared for effector functions such as helper and cytolytic functions. These functions are likely to be critical in maintaining normal host defense in the mucosal environment.     

人类免疫缺陷病毒感染后不同疾病阶段的胃黏膜病理改变

目的 评价胃黏膜中CD4~+T淋巴细胞群与外周血CD4~+T淋巴细胞及病毒载量的相关性.探讨HIV感染后不同疾病阶段患者的胃黏膜病理改变.方法 选取HIV感染者36例,根据全血CD4~+T淋巴细胞计数和临床症状,将研究对象分为HIV感染无症状者和AIDS患者两组,免疫组织化学方法检测CD4~+T淋巴细胞在胃黏膜中的表达,以直线回归分析、Spearman等级相关分析进行统计.结果 随着疾病的进展,HIV感染者胃黏膜腺体萎缩和间质增生逐渐加重,而黏膜中浸润炎性细胞及淋巴细胞进行性减少,并普遍存在淋巴细胞噬黏膜腺体现象.HIV感染者血清病毒载量与胃黏膜内CD4~+T淋巴细胞呈负线性相关(r=-0.336,P=0.01),全血CD4~+T淋巴细胞与胃黏膜中CD4~+T淋巴细胞呈正相关(r=0.5762,P<0.01).结论 HIV感染后,患者胃黏膜组织出现多种病理改变,并随着病程阶段的进展而加重,胃黏膜中CD4~+T淋巴细胞群与全血CD4~+T淋巴细胞计数和病毒载量的相关性即是这种改变的具体体现.     

Cells and cytokines in mucosal immunity and inflammation.

The mucosal immune system consists of a number of compartments that are populated with a different assortment of cells and serve different functions. The cytokines produced by the cells in each of these compartments are currently being defined. This is best understood in relation to B cells, whose proliferation and maturation is guided by a sequence of cytokines. PP are inductive sites that preferentially stimulate IgA production. At least in part, this preference seems to be due to the T cells located in PP, which have been shown to stimulate switching to IgA production by cognate interactions and production of TGF-beta. Postswitch B cells expressing surface IgA respond to IL-5, a cytokine produced by T cells in GALT. Terminal differentiation to IgA-producing plasma cells in the lamina propria may be driven by IL-6, which can be produced by a variety of cells in the lamina propria and by epithelial cells. T cells in the lamina propria have an assortment of surface markers consistent with both activation and memory and appear to produce a variety of cytokines in the local environment that presumably act in normal host defense. IEL consist mainly of CD8+ T cells. They have been shown to produce IFN-gamma and, very likely, other cytokines that presumably act in a paracrine fashion on local enterocytes. How these cells and cytokines are perturbed during intestinal inflammation is currently being defined. A certain assortment of cytokines are greatly increased in IBD. This assortment, including IL-1, IL-6, and IL-8, is elevated in a wide variety of chronic inflammatory states in other tissues as well. A critical requirement for cytokines to exert their effects is the expression of specific receptors on target cells. Virtually nothing is known about this aspect of mucosal immunity, but receptor expression on mucosal cells must be defined before we will be able to understand the complex interactions among lymphoid cells, the cytokines they produce, and the local stromal and epithelial cells.     

Chronic colitis associated with HIV infection can be related to intraepithelial infiltration of the colon by CD8+ T lymphocytes

Gastrointestinal complications in AIDS patients with diarrhoea are common clinical manifestations, frequently diagnosed by colonoscopy as non-specific colitis. We retrospectively study colon biopsies diagnosed as chronic colitis associated with HIV (CCH). Biopsies were sorted as patients with AIDS (serum CD4 <200 cell/mm3) but without any clear infectious process (n = 12) and patients without HIV infection (n = 24). There are low numbers of CD4+ T lymphocytes in lamina propria of AIDS patients, but CD8+ T populations in this area appear to be similar in all studied groups, regardless of HIV infection or laboratory evidence of a specific agent. We found the clear evidence of CD8+ T cells infiltration in colonic mucosa in HIV patients with microscopic colitis. An imbalance of lymphocyte subpopulations in the colon, both in the lamina propria and epithelium, could result in an intraepithelial CD8 infiltration, involved in the pathogenesis of CCH in AIDS patients.     

Intestinal mucosal immunosenescence in rats.

The elderly are characterized by systemic immunosenescence and high rates of morbidity and mortality associated with infectious diseases of the intestinal tract. Despite the consensus that the mucosal immune compartment is largely unaffected by aging, there are marked deficits in the intestinal mucosal immune responses of old animals and elderly humans. However, little is known about the mechanism(s) whereby aging disrupts intestinal immunity. Events in the generation of an intestinal immune response may be susceptible to the insults of aging. The first step involves the uptake of antigens by specialized follicular epithelial cells (M cells). There have been no studies on the efficacy of antigen uptake by M cells as a function of age. Little is known about the next step, i.e. antigen presentation by dendritic cells and subsequent isotype switching. The third event is the differentiation of putative immunolobulin A (IgA) plasma cells and their homing from the Peyer's patches (inductive site) to the lamina propria of the small intestine (effector site). Quantitative immunohistochemical and flow cytometry analyses suggest that the homing of IgA immunoblasts may be compromised in old rats and monkeys. Local antibody production/secretion by mature IgA plasma cells in the intestinal wall constitutes the fourth step. In vitro anti-cholera toxin IgA antibody secretion by intestinal lamina propria lymphocytes is equivalent in cells isolated from young adult and senescent rats. The final event in the mucosal immune response is the transport of IgA antibodies across the mucosal epithelial cells and their secretion onto the mucosal surface, i.e. receptor-mediated vesicular translocation of IgA by the intestinal epithelial cells. Binding assays did not detect age-associated declines in either the number or binding affinity of the polymeric immunoglobulin receptor expressed on rodent and monkey intestinal epithelial cells.     

Both substance P and its receptor are expressed in mouse intestinal T lymphocytes

Substance P (SP), one of the most prevalent neuropeptides in gut, has been reported to have potent immune modulatory effects as a proinflammatory agent. The synthesis of SP and SP receptor expression in intraepithelial and lamina propria T lymphocytes of mouse intestine was investigated. Using RT-PCR analysis, it was demonstrated that SP receptor mRNA was exclusively expressed in intraepithelial and lamina propria T lymphocytes as well as their purified CD4+, CD8+ and CD4-CD8-CD3+ subsets. Messenger RNAs (mRNAs) for the two precursors of SP, beta and gamma-preprotachykinin-A, were also detected. These results were consistent in lymphocytes from both epithelium and lamina propria of small and large intestines, although the frequencies and/or intensities of mRNA expression varied. However, none of the findings could be repeated in splenic T lymphocytes. Activation of splenocytes with anti-CD3epsilon-chain mAb and PMA did not induce expression of SP or its receptor mRNAs. Furthermore, both cytoplasmic and surface-bound SP was demonstrated in intestinal T lymphocytes using dual color immunocytochemistry and immunoflow cytometry. In vitro treatment with SP did not significantly change the size of the SP-immunoreactive T cell population, indicating the presence of SP receptor on intestinal T lymphocytes as well as in vivo binding of endogenously released SP. Our data suggest that SP production and SP receptor expression are distinctive for mouse intestinal mucosal immunity and that SP may act as a modulator of an ongoing controlled inflammation in normal gut, by acting through its specific receptor on T lymphocytes in an autocrine and/or paracrine pattern.     

CD4+CD7-CD57+ T cells: a new T-lymphocyte subset expanded during human immunodeficiency virus infection.

CD7 and CD57 are two cell surface molecules related to the differentiation or functional stages of CD4+ T cells. The CD4+CD7- T cells represent a minor subset of CD4+ cells in normal individuals and are considered to contain the normal counterpart of Sézary T cells; the CD4+CD57+ peripheral blood lymphocytes (PBL) are detectable in long-term renal allograft recipients. We compared the cell surface expression of these CD7 and CD57 markers on CD4+ T lymphocytes in peripheral blood and lymphoid organs from normal individuals and human immunodeficiency virus (HIV)-infected patients. Our results indicate that CD4+CD7- T cells in normal PBL do not express CD57 and were poorly responsive to anti-CD3 monoclonal antibody (MoAb), the activation being restored by addition of anti-CD28 MoAb. This CD4+CD7- cell subset is increased in peripheral blood during HIV infection, and its progressive expansion mirrors both the absolute and relative decrease of CD4+ T cells. The lack of CD7 expression is correlated with CD57 acquisition on CD4+ T cells because CD4+CD7-CD57+ cells represent a major component of the CD4+CD7- subset in HIV-infected patients. Our results suggest that the presence and the expansion of CD4+CD7-CD57+ T lymphocytes, which do not behave as previously defined helper subsets, may participate to the immune dysfunction observed during HIV infection.     

Lymphoid organs function as major reservoirs for human immunodeficiency virus.

The total number of human immunodeficiency virus type 1 (HIV-1)-infected circulating CD4+ T lymphocytes is considered to be a reflection of the HIV burden at any given time during the course of HIV infection. However, the low frequency of HIV-infected circulating CD4+ T lymphocytes and the low level or absence of plasma viremia in the early stages of infection do not correlate with the progressive immune dysfunction characteristic of HIV infection. In this study, we have determined whether HIV-infected circulating CD4+ T lymphocytes are a correct reflection of the total pool of HIV-infected CD4+ T cells (i.e., HIV burden). To this end, HIV burden has been comparatively analyzed in peripheral blood and lymphoid tissues (lymph nodes, adenoids, and tonsils) from the same patients. The presence of HIV-1 DNA in mononuclear cells isolated simultaneously from peripheral blood and lymphoid tissues of the same patients was determined by polymerase chain reaction amplification. We found that the frequency of HIV-1-infected cells in unfractionated or sorted CD4+ cell populations isolated from lymphoid tissues was significantly higher (0.5-1 log10 unit) than the frequency in peripheral blood. Comparable results were obtained in five HIV seropositive patients in the early stages of disease and in one patient with AIDS. These results demonstrate that a heavy viral load does reside in the lymphoid organs, indicating that they may function as major reservoirs for HIV. In addition, the finding of a heavy viral load in the lymphoid organs of patients in the early stages of disease may explain the progressive depletion of CD4+ T lymphocytes and the immune dysfunction associated with the early stages of HIV infection.     

Duodenal Intraepithelial and Lamina Propria T Lymphocytes in Human Immunodeficiency Virus-Infected Patients with and without Diarrhoea

Background: Diarrhoea is an important problem in human immunodeficiency virus (HIV)-infected patients. Intestinal pathologic conditions may arise from changes in local immunocyte populations. The aims of our study were to establish the histologic features of the duodenal mucosa of HIV-infected patients and to determine a) the phenotype of small-intestinal—intraepithelial (IELs) and lamina propria (LPLs)—lymphocytes; b) their degree of activation and differentiation within the lamina propria; and c) their relation to the presence of diarrhoea. Methods: Distal duodenal biopsy specimens were obtained prospectively from 29 HIV-infected patients—11 patients with diarrhoea (group 1) and 18 patients without diarrhoea (group 2)—and from 42 patients who had neither any risk factor for HIV nor diarrhoea (group 3). Histopathologic and immunohistochemical studies were combined with flow cytometric analysis, after separation of the mucosal intraepithelial compartment from the lamina propria. Results: The median number of IELs and the percentage of γ$dL IELs were both unchanged in HIV-infected patients as compared with controls. In HIV-infected patients LP CD4 cells were decreased, and LP CD8 cells increased. No significant difference was found in the expression of CD25 or CD27 within the LP CD8 populations of HIV-infected patients in groups 1 and 2. Conclusions: These findings suggest that the occurrence of diarrhoea in HIV-infected patients is unrelated to IEL and LPL phenotype.     

肠黏膜免疫:刚地弓形虫感染中抗体分泌细胞及sIgA的地位

病原体经口感染机体后,肠相关淋巴组织受刺激,促进肠黏膜内IgA抗体分泌细胞(IgAASC)的形成,并向肠腔分泌大量的分泌型免疫球蛋白A(sIgA),IgA ASC和sIgA在肠黏膜免疫应答中起了重要作用.BALB/c小鼠经口感染弓形虫RH速殖子后,小鼠小肠黏膜固有层IgA ASC大量增殖,小肠冲洗液sIgA水平持续增高,发挥抗虫效应.小肠冲洗液sIgA水平与十二指肠黏膜IgA ASC数量呈正相关(r＝0.732,P<0.01).用可溶性速殖子抗原(STAg)鼻内免疫小鼠可诱导卜二指肠黏膜固有层IsAASC高表达,小肠液和血清sIgA水平升高,表明在抗弓形虫感染中STAg鼻内免疫发挥了作用.