不同复苏溶液对失血性休克大鼠中性粒细胞CD11a、CD11b表达的影响

目的观察不同复苏溶液对失血性休克大鼠PMN表面CD11a、CD11b表达的影响.方法成年Wistar大鼠随机分为0.9%NaCl(NS)、7.5%NaCl(HS)、5%NaCl-3.5%NaAc(HSA)三组,每组6只.动物麻醉后,自股动脉放血,于10min内使MAP下降至5.07-5.47kPa,维持90min.按4mL/kg体重分别注入NS、HS、HSA,5min内输完.随后输注三倍最大失血量的复方氯化钠溶液,40min内输完.分别于休克前、后、给液后1.5h、3h、6h取血0.2mL,流式细胞仪测定PMN表面CD11a、CD11b表达的变化.结果休克后,各组PMN表面CD11a表达下降,但与休克前比较无显著差别.给液后1.5h,各组CD11a表达继续下降;给液后3h,各组CD11a表达稍有回升;给液后6h,各组CD11a表达又呈下降趋势,HSA组CD11a表达显著低于休克前水平;各组间于各时相点均无显著差别.休克后,各组PMN表面CD11b表达增加,与休克前比较有非常显著差别.给液后3h内,各组CD11b表达随观察时间的延长呈进行性增加;给液后6h,NS组CD11b表达继续增加,HS组和HSA组CD11b表达有下降趋势.各组CD11b表达于给液后各时相点均较休克前和休克时非常显著增加,HS组和HSA组CD11b表达于给液后各时相点均低于NS组,但无显著差别.结论液体复苏后,失血性休克大鼠PMN表面CD11a表达呈下降趋势,CD11b表达呈上升趋势,HS和HSA有减弱这种趋势的作用.     

支气管哮喘与PBMC上CD11a、CD18、CD44分子表达的关系

本文探讨 β整合素家族及CD44粘附分子在哮喘发病中的作用。采用流式细胞仪分别检测哮喘豚鼠外周血单个核细胞(PBMC )表面CD11a分子及哮喘患者PBMC表面CD18和CD44等分子的表达情况。结果 :(1)哮喘豚鼠PBMC表面CD11a分子表达明显高于对照组 (P <0 0 1) ,地塞米松可抑制CD11a表达 ;(2 )哮喘患者PBMC表面CD18、CD44表达较正常人明显增高 (P <0 0 1)。使细胞粘附分子参与了哮喘的病理生理过程 ,糖皮质激素可抑制细胞粘附分子表达 ,发挥抗炎作用。     

外周血干细胞动员调节CD34^＋细胞β整合素及L—选择素的表达

目的：观察造血干细胞表面粘附分子的变化在外周血干细胞动员中的作用。方法：用双色免疫荧光法研究15例恶性血液病患者经化疗＋G－CSF动员外击血干细胞前后、骨髓和外周血CD34^ 细胞表面β1整合素（CD49d）、β2整合素（CD11a、CD11b）及L－选择素（CD62L）的表达。结果：①动员后第7天CD34^ 细胞表面较动员前CD49d、CD11a、CD62L表达下降;（P＜0．01）,而CD11b无变化（P＞0．05）。②外周血CD34^ 细胞表达CD49d、CD11a、CD11b、CD62L较骨髓低（P＜0．05）。③外周血CD34^ 细胞绝大多数处于GO／G1期,该期的的干细胞CD49d的密度低于S＋G2／M期。结论：化疗＋G－CSF通过粘附分子的变化而使造血干细胞从骨髓进入外周血中。     

外周血干细胞动员调节CD34+细胞β整合素及L-选择素的表达

目的观察造血干细胞表面粘附分子的变化在外周血干细胞动员中的作用。方法用双色免疫荧光法研究15例恶性血液病患者经化疗+G-CSF动员外周血干细胞前后、骨髓和外周血CD34+细胞表面β1整合素(CD49d)、β2整合素(CD11a、CD11b)及L-选择素(CD62L)的表达。结果①动员后第7天CD34+细胞表面较动员前CD49d、CD11a、CD62L表达下降(P＜0.01),而CD11b无变化(P＞0.05)。②外周血CD34+细胞表达CD49d、CD11a、CD11b、CD62L较骨髓低(P＜0.05)。③外周血CD34+细胞绝大多数处于GO/G1期,该期的干细胞CD49d的密度低于S+G2/M期。结论化疗+G-CSF通过粘附分子的变化而使造血干细胞从骨髓进入外周血中。     

整合素β1在异丙肾上腺素诱导大鼠心肌肥厚组织中的表达

目的　观察心肌肥厚大鼠心肌组织中整合素β1的表达变化。 方法　在大鼠背部皮下分别注射7 d、28 d和56 d异丙肾上腺素（ISO）,判定心肌肥厚指标,利用免疫组织化学和免疫印迹技术,观察整合素β1在肥厚左心室肌中的表达。 结果　免疫组化和Western blot结果显示,整合素β1主要表达于心肌细胞膜。与对照组相比,实验各组大鼠的心肌组织的整合素β1表达明显（P<0.05）。7 d、28 d和56 d各组间相比其表达含量逐渐增强。 结论　在心肌肥厚状态下,心肌细胞中的整合素β1表达增高,随着心肌肥大的进展其表达逐渐增加,提示整合素β1在心肌肥厚发生发展起重要作用。     

重症烧伤休克大鼠白细胞表面beta-2整合素的表达

目的 :阐明烧伤休克时 beta-2整合素与白细胞 -内皮细胞粘附间的关系。方法 :将 16只 SD大鼠随机均分为对照组和烧伤休克组。应用流式细胞技术检测中性粒细胞及单细胞表面 beta-2整合素CD11a( LFA-1)和 CD11b( Mac-1)的表达量变化 ,同时比较观察二组动物肠系膜微循环中微静脉内白细胞与内皮细胞粘附数量变化。结果 :二组自身对照 (烫伤前与烫伤后 3 h或开腹前与开腹后 3 h)及相互对比结果显示 ,中性粒细胞及单核细胞表面 CD11a表达量均无显著差异 ( P>0 .0 5 ) ;在烧伤组 ,单核细胞 CD11b有显著降低( P<0 .0 5 ) ,而中性粒细胞 CD11b有显著升高 ( P<0 .0 5 )。微循环观察结果显示 ,休克组动物烫伤后随时程延长附壁滚动及紧密粘附的白细胞数量明显增多 ,而对照组则无明显变化。结论 :烧伤休克状态下 ,白细胞表面 CD11a数量无显著变化 ,而 CD11b数量则有所改变。白细胞 -内皮细胞粘附力的增强可能有 beta-2整合素功能活性上调参与。     

肺炎链球菌肺炎对肺部树突状细胞及CD4~+T细胞的影响

目的探讨肺炎链球菌肺炎对Balb/c小鼠肺部树突状细胞及CD4~+T细胞的影响。方法 6~8周Balb/c小鼠随机分为对照组及肺炎链球菌感染组,流式细胞术检测肺炎链球菌感染后2 d、5 d肺组织中CD103~+DCs、CD11b~+DCs、p DCs及CD4~+T细胞亚类水平。结果肺炎链球菌肺炎致肺组织CD103~+DCs及p DCs水平显著增高,与对照组比较差异有统计学意义(P0.01),而肺组织CD11b~+DCs水平显著低于对照组。肺炎链球菌肺炎促进肺组织IL-17A~+CD4~+T细胞和Foxp3~+Tregs表达,与对照组比较,感染后2 d、5 d差异均有统计学意义(P0.05),随着感染控制,Foxp3~+Tregs表达水平回降,感染后5 d Foxp3~+Tregs水平显著低于感染后2 d水平(7.3%±0.41%vs 9.38%±1.34%,P0.01)。肺炎链球菌肺炎对肺部Th2表达水平无显著影响,感染后5 d IFN-γ~+CD4~+T细胞水平显著升高,与对照组、感染后2 d组比较,差异有统计学意义(P0.01)。结论肺炎链球菌肺炎促进肺组织CD103~+DCs、p DCs表达,诱导CD4~+Th17、Tregs细胞分化发育。     

尸肾移植急性排斥反应与患者淋巴细胞CD62L、CD11a、CD4、CD8表达的关系

为探讨同种异体尸肾移植排斥反应病人淋巴细胞CD62L、CD11a表达与T细胞亚群及CD4/CD8的关系和意义。利用单克隆抗体 流式细胞仪荧光免疫技术 ,测定 10例肾移植排斥反应病人术后不同时间外周血淋巴细胞CD62L、CD11a、CD4、CD8表达并计算CD4/CD8。结果 ,肾移植病人排斥反应时其CD62L (4 6 1± 18 7vs 31 3± 10 5 ,P <0 0 1)、CD11a (4 9 5±2 0 2vs 31 9± 12 4,P <0 0 1)、CD4(2 4 4± 7 7vs 17 9± 7 4,P <0 0 1)、CD8(14 7± 2 9vs 10 4± 3 2 ,P <0 0 5 )表达均较排斥前明显增加 ,抗排斥治疗后CD11a (14 8± 6 2vs 49 5± 2 0 2 ,P <0 0 1)、CD4(15 8± 6 4vs 2 4 4± 7 7,P <0 0 5 )和CD4/CD8(1 2 8± 0 6vs 1 73± 0 79,P <0 0 5 )均明显下降。CD62L变化和CD8呈明显正相关 (r=0 9779,P <0 0 5 )。认为淋巴细胞CD62L、CD11a、CD4、CD8表达及CD4/CD8与肾移植排斥反应密切相关。免疫抑制剂 ,尤其甲基强的松尤能明显抑制淋巴细胞CD11a、CD4表达和CD4/CD8比值可能是其发挥抗排斥作用的重要机制。     

不同年龄大鼠脑组织中MHC、CD4及CD8分子的表达及其意义

目的：探讨MHC、CD4及CD8分子在不同年龄的大鼠脑组织中的表达及其意义.方法：将实验大鼠按胎龄和日龄分为7组：E15、E19、P0、P7、P14、P28及老年组（24月龄）;采用免疫组化方法,检测MHC、CD4和CD8分子在大鼠脑组织中海马区、脉络丛、大脑皮质及结缔组织的表达.结果：（1）E15d大鼠脑组织未见MHC Ⅰ类分子的表达;其他年龄组在结缔组织和脉络丛有MHC Ⅰ类分子的表达.其中从P0 d组～P14 d组大鼠的海马和部分大脑皮质神经元上MHCⅠ类分子的表达逐渐升高,P14 d组的表达最高（P＜0.05）;P28 d组的表达明显下降（P＜0.05）;老年组大鼠海马神经元上的表达再次升高（P＜0.05）.（2）E15 d组大鼠脑组织中未见MHC Ⅱ、CD4和CD8分子的表达;其他年龄组MHC Ⅱ、CD4和CD8除在结缔组织和脉络丛脉络膜表达外,在神经元上未见表达.（3）各年龄组在小脑皮质神经元上未见MHC Ⅰ、Ⅱ、CD4和CD8分子的表达.结论：胚胎后期脑内开始有MHC、CD4和CD8分子的表达,表明此时脑内已有可能出现免疫反应.在新生鼠及出生早期,部分皮质和海马神经元上有MHC Ⅰ类分子的表达,可能与调节神经元活动和突触可塑性连接有关.老年组大鼠MHC Ⅰ类分子在海马神经元上的表达升高,可能与神经元的功能衰退和记忆识别能力下降有关.     

缺氧缺血性脑病新生儿血清胰岛素(InS)及、中性粒细胞表面黏附分子CD_(11b)表达的变化

目的观察缺氧缺血性脑病(HIE)新生儿血清胰岛素(In S)的水平及中性粒细胞表面黏附分子CD11b的表达,探讨其在HIE中的临床意义。方法足月HIE患儿59例(轻度12例,中度30例,重度17例)及35例健康足月新生儿(健康对照组)分别于出生72h取静脉血采用化学发光法检测血清In S水平,同时采用流氏细胞术检测中性粒细胞表面黏附分子CD11b的表达,比较各组间的差异;并分析HIE各组中In S与CD11b水平的相关性。结果 1.HIE组血清In S水平及CD11b表达水平显著高于健康对照组(P均0.01);2.HIE各组血清In S水平及CD11b表达水平随HIE程度加重而增加,各组间差异均有统计学意义(P均0.05);3.HIE患儿血清In S水平及CD11b表达水平呈正相关(r=0.849,P0.05)。结论血清In S水平及CD11b表达水平可作为HIE新生儿病情严重程度早期指标;HIE的发生、发展可能是多因素联合参与的过程,其中免疫、炎症反应及神经内分泌系统的变化等异常同步发生,相互关联。     

Aggravated Lyme carditis in CD11a-/- and CD11c-/- mice

CD18 hypomorph mice expressing reduced levels of the common beta2 integrin chain develop aggravated Lyme carditis, compared to that developed by wild-type (WT) mice, upon infection with the spirochete Borrelia burgdorferi. The enhancement of Lyme carditis in these mice is characterized by increased macrophage infiltration, correlating with augmented expression of the monocyte/macrophage chemoattractant protein 1 (MCP-1). The lack of CD18 results in the deficiency of all beta2 integrins, i.e., CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1/CR3), CD11c/CD18 (p150,95/CR4), and CD11d/CD18. To determine the roles of the various beta2 integrins in controlling the development of aggravated Lyme carditis, disease induction was analyzed in CD11a-/-, CD11b-/-, and CD11c-/- mice. CD11a-/- and CD11c-/- mice, but not CD11b-/- mice, developed aggravated Lyme carditis after exposure to B. burgdorferi. Similarly to CD18 hypomorph mice, CD11c-/- mice expressed higher levels of MCP-1, compared to both WT and CD11a-/- mice, as determined by in vitro analysis of MCP-1 secretion by bone marrow-derived dendritic cells and in vivo analysis of MCP-1 mRNA expression in B. burgdorferi-infected hearts. On the other hand, CD11a deficiency was associated with heightened heart B. burgdorferi burden relative to that of WT mice. Overall, our results suggest that the increased severity of Lyme carditis in CD18 hypomorph mice is caused by deficiency in CD11a or CD11c, possibly via different mechanisms.     

Altered expression of CD11/CD18 on the peripheral blood phagocytes of patients with tuberculosis.

Tuberculosis (TB), caused by Mycobacterium tuberculosis, is characterized by granulomatous lesions made up of epithelioid cells, giant cells and mononuclear leucocytes. Cell-cell adhesion is important in granuloma formation and in the leucocyte migration which accompanies it. We have recently shown increased expression of the adhesion molecules CD11/CD18 (LeuCAMs, beta 2 integrins) on peripheral blood leucocytes from patients with sarcoidosis (Shakoor & Hamblin, 1992). Here we have studied the expression of CD11/CD18 and CD29 (VLA beta 1 integrin) on the peripheral blood leucocytes of 10 TB patients by flow cytometry. The density (expressed as mean fluorescence intensity) of CD11b on monocytes and polymorphs was increased (P < 0.005), as was CD11c (P < 0.005) and CD18 (P < 0.05) on polymorphs. CD11a expression was significantly reduced on polymorphs (P < 0.05). No differences were found in the expression of CD29, the percentages of cells expressing any molecule and, in contrast to sarcoidosis, the density of any molecule on lymphocytes. Although the cytokine tumour necrosis factor (TNF) has been implicated in the process of up-regulation, an ELISA for TNF failed to detect significant levels in plasma. The results suggest increased peripheral phagocyte CD11/CD18 expression is a feature of TB, which may contribute to the pathological processes involved.     

Characterization of the rat leukocyte integrin, CD11/CD18, by the use of LFA-1 subunit-specific monoclonal antibodies.

We have attempted to characterize the rat leukocyte integrin, CD11/CD18, by the use of newly generated monoclonal antibodies (mAb) WT.1 (anti-CD11a) and WT.3 (anti-CD18) in conjunction with an mAb, OX42, reactive with a rat integrin-like molecule, with respect to the biochemistry, cellular distribution and function. The conclusion that the mAb WT.1 and WT.3 specifically recognize the rat CD11a and CD18, respectively, was based on: (a) their ability to inhibit homotypic aggregation of splenic concanavalin A (Con A) blasts; (b) sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the antigens recognized; (c) their ability to inhibit binding of Con A blasts to the purified ligand, namely the ICAM-1 antigen and (d) their blocking abilities in mixed leukocyte reaction. In the rat, CD18 has an apparent molecular mass of 95-100 kDa and can associate with at least three distinct alpha subunits of 160-170 kDa (CD11a), 140-150 kDa and 120-130 kDa. The latter two are precipitated by OX42 from M phi but not from unstimulated lymphocytes. They presumably represent the rat CD11b and CD11c, respectively. Rat thymocytes, PBL, thoracic duct lymphocytes, monocytes and neutrophils expressed differential levels of CD11a and CD18. Peritoneal M phi showed virtually no CD11a expression, although CD18 was expressed at levels similar to those seen on blood monocytes, showing an interesting pattern of LFA-1 expression regulation in this cell lineage. Both WT.1 (anti-CD11a) and WT.3 (anti-CD18) apparently recognize a "low-affinity" as well as a "high-affinity" form of LFA-1 and do not discriminate between the two.     

Integrin CD11c contributes to monocyte adhesion with CD11b in a differential manner and requires Src family kinase activity

Integrin-mediated adhesion of human monocytes to fibrinogen regulated by CD11b/CD18 and the closely related integrin CD11c/CD18, play a key role in inflammation. Peripheral blood monocytes isolated from human donors despite expressing CD11c primarily utilized CD11b to mediate adhesion to fibrinogen upon stimulation with granulocyte macrophage-colony stimulating factor (GM-CSF) and fMLP. Blocking with anti-CD11b resulted in 90% (p<0.001, n=3) inhibition of monocyte adhesion. Monocytes cultured in human serum showed a shift in the participation of integrins, adhesion to fibrinogen involving both CD11b and CD11c. The participation of CD11c in cultured monocytes corresponded to a 3.4-fold increase in expression in CD11c. Blocking cultured monocytes with anti-CD11b or anti-CD11c alone showed no significant effect on adhesion. Treatment with both anti-CD11b and anti-CD11c resulted in inhibition of adhesion by 85% (p<0.001, n=3). Abrogation in adhesion upon treatment with PP1 or PP2 showed that Src family kinase activity was required for CD11b and CD11c mediated adhesion of cultured monocytes to fibrinogen upon stimulation with GM-CSF and fMLP. The clustering of CD11c on cultured monocytes upon adhesion to fibrinogen was diminished on inhibition with PP2 indicating a role for Src family kinase activity in regulating CD11c avidity. CD11b was critical to cytoskeletal events leading to increased spreading and formation of actin foci in cultured monocytes following adhesion to fibrinogen. Blocking cultured monocytes with anti-CD11b or anti-CD11c alone showed that the increase in spread area was diminished by 67+/-3% and 36+/-9%, respectively. The differential involvement of CD11c and CD11b in adhesion and subsequent cytoskeletal changes in monocytes exposed to different conditions indicates the importance of each integrin in distinct responses during inflammation.     

Participation of CR1 (CD35), CR3 (CD11b/CD18) and CR4 (CD11c/CD18) in membranoproliferative glomerulonephritis type I.

Intraglomerular expression of complement receptors (CR) was investigated chronologically in 22 repeatedly biopsied patients with membranoproliferative glomerulonephritis (MPGN) type I by indirect immunoperoxidase staining using MoAbs. Patients were divided into two groups based on whether intraglomerular C3c deposition was decreased at the second biopsy (2nd Bx) (group A, n = 12), or not (group B, n = 10). At the first biopsy (1st Bx), the severity of glomerular injury and the degree of glomerular C3c deposition were compatible between the two groups. Four patterns of CR1 (CD35) expression on podocytes were recognized: normal; generally decreased; focally/segmentally lost; and completely lost. The numbers of CR3 (CD11b/CD18)- and CR4 (CD11c/CD18)-positive cells per glomerular cross-section were counted. At the 1st Bx, no significant difference was found in the number of CR3+ or CR4+ cells between the two groups. At the 2nd Bx, the numbers of both the CR3+ and CR4+ cells were significantly decreased only in group A (P < 0.01). The numbers of CR3+ and CR4+ cells were significantly higher in cases with moderate or marked C3c deposits than in those with no or mild C3c deposits. The intensity of CR1 expression in group B was less than that in group A at both the 1st and 2nd Bx (1st, P < 0.05; 2nd, P < 0.01), and chronological improvement of CR1 expression was observed only in group A. The severity of glomerular injury was increased only in group B (P < 0.01), and was associated with persistent massive proteinuria and hypocomplementaemia. Our results suggest that, in cases with an adverse outcome, a more severe defect of CR1 initially exists and the expression of CR1 is not recoverable chronologically. This irreversible decrease or loss of CR1 may partly contribute to the continuous C3c deposition and intraglomerular infiltration of CR3+ and CR4+ cells.     

Changes in neutrophil CD11b/CD18 andl-selectin expression and release of interleukin 8 and elastase in paediatric cardiopulmonary bypass

Children undergoing cardiopulmonary bypass (CPB) surgery for congenital heart defects develop an acute post-operative capillary leak which may be due to endothelial injury inflicted by adherent neutrophils (PMN). Direct immunofluorescence and flow cytometry were used to measure CD11a/CD18, CD11b/CD18 andl-selectin (l-s) expression on circulating PMN in CPB circuits containing human blood and in children undergoing CPB.In vitro, a general rise in CD11b/CD18 expression over 2h contrasted with complete loss ofl-s in a small but progressively increasing proportion of PMN. Marked but inconsistent changes in CD11b/CD18 andl-s were observedin vivo, in conjunction with fluctuations in circulating PMN count. Circulating IL-8 was detected starting at rewarming from hypothermia and reperfusion of the heart and lungs with a simultaneous, closely correlated rise in both PMN count and circulating elastase. IL-1 and TNF were not detected. These studies demonstrate changes in the pathways of PMN-endothelial interaction during and after CPB.     

Characterization of four CD18 mutants in leucocyte adhesion deficient (LAD) patients with differential capacities to support expression and function of the CD11/CD18 integrins LFA-1, Mac-1 and p150,95.

Leucocyte adhesion deficiency (LAD) is a hereditary disorder caused by mutations in the CD18 (beta2 integrin) gene. Four missense mutations have been identified in three patients. CD18(A270V) supports, at a diminished level, CD11b/CD18 (Mac-1, alphaMbeta2 integrin) and CD11c/CD18 (p150,95, alphaXbeta2 integrin) expression and function but not CD11a/CD18 (LFA-1, alphaLbeta2 integrin) expression. Conversely, CD18(A341P) supports a limited level of expression and function of CD11a/CD18, but not of the other two CD11/CD18 antigens. CD18(C590R) and CD18(R593C) show a decreasing capacity to associate with the CD11a, CD11c and CD11b subunits. Transfectants expressing the CD11a/CD18 with the C590R and R593C mutations are more adhesive than transfectants expressing wild-type LFA-1, and express the reporter epitope of the monoclonal antibody 24 constitutively. Thus, the four mutations affect CD18 differently in its capacities to support CD11/CD18 expression and adhesion. These results not only provide a biochemical account for the clinical diversity of patients with leucocyte adhesion deficiency, but also offer novel insights into the structural basis of interaction between the alpha and beta subunits, which is an integral component in our understanding of integrin-mediated adhesion and its regulation.     

In vitro effects of oxidized low density lipoprotein on CD11b/CD18 and L-selectin presentation on neutrophils and monocytes with relevance for the in vivo situation.

Oxidized LDL (oxLDL) has been identified as a potent stimulus of leukocyte adhesion to endothelium, a hallmark of early atherogenesis. A cytofluorometric study was performed to further characterize the mechanisms by which oxLDL stimulates the rapid adhesion of leukocytes to endothelium in vitro and in vivo. Incubation (30 minutes at 37 C) of whole blood (diluted with buffered saline to 1 x 10(6) leukocytes/ml) with oxLDL (0.85 mg LDL cholesterol/ml; oxidized by 7.5 mumol/L Cu2+ for 18 hours) but not native LDL stimulated the upregulation of CD11b/CD18 adhesion receptors on neutrophils (anti-leu-15 binding: 178 +/- 16% of baseline, P < 0.01, means +/- SD of n = 10 experiments) and on monocytes (169 +/- 34% of baseline, P < 0.01). This phenomenon was almost entirely inhibited by n-butanol or the vasoactive drug pentoxifylline (PTX), which also significantly reduced oxLDL-induced leukocyte adhesion to venular and arteriolar endothelium, as assessed by intravital microscopy on the dorsal skinfold chamber in hamsters (venules: 49 +/- 19 versus 120 +/- 34 cells/mm2, P < 0.05; arterioles: 9 +/- 4 versus 52 +/- 7 cells/mm2, P < 0.01) 30 minutes after intravenous injection of oxLDL (4 mg/kg body weight; means +/- SD of n = 7 hamsters per group). Butanol and PTX also significantly reduced the upregulation of CD11b/CD18 by f-methionyl-leucyl-phenylalanine (fMLP) and platelet-activating factor (PAF) but not by phorbol myristate acetate (PMA). Whereas fMLP and PAF stimulate leukocytes via binding to specific cell surface receptors and triggering complex signal transduction pathways, PMA bypasses these pathways and directly activates intracellular protein kinase C. By analogy, we propose that oxLDL upregulates CD11b/CD18 through its previously documented ability to stimulate the generation of second messengers. The effect of n-butanol and PTX on receptor presentation cannot be explained by changes in plasma membrane fluidity, as both agents failed to reverse the decrease in plasma membrane fluidity of neutrophils after stimulation with oxLDL, as assessed by fluorescence anisotropy measurement of the membrane marker diphenylhexatriene. Incubation of isolated neutrophils but not of whole blood with oxLDL resulted in a significant loss of L-selectin from the neutrophil surface (anti-TQ-1 binding: 40 +/- 13% of baseline, P < 0.01). A significant loss of this adhesion receptor on neutrophils and monocytes was also observed after stimulation of isolated neutrophils and whole blood with fMLP, PAF, and PMA.(ABSTRACT TRUNCATED AT 400 WORDS)     

Porphyromonas gingivalis Fimbriae Use β2 Integrin (CD11/CD18) on Mouse Peritoneal Macrophages as a Cellular Receptor, and the CD18 β Chain Plays a Functional Role in Fimbrial Signaling

In this study, we demonstrate that Porphyromonas gingivalis fimbriae use molecules of β₂ integrin (CD11/CD18) on mouse peritoneal macrophages as cellular receptors and also show that the β chain (CD18) may play a functional role in signalling for the fimbria-induced expression of interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) genes in the cells. Using a binding assay with ¹²⁵I-labeled fimbriae, we observed that fimbrial binding to the macrophages was inhibited by treatment with CD11a, CD11b, CD11c, or CD18 antibody but not by that with CD29 antibody. Western blot assays showed that the fimbriae bound to molecules of β₂ integrin (CD11/CD18) on the macrophages. Furthermore, Northern blot analyses showed that the fimbria-induced expression of IL-1β and TNF-α genes in the cells was inhibited strongly by CD18 antibody treatment and slightly by CD11a, CD11b, or CD11c antibody treatment. Interestingly, intracellular adhesion molecule 1 (ICAM-1), a ligand of CD11/CD18, inhibited fimbrial binding to the cells in a dose-dependent manner. In addition, ICAM-1 clearly inhibited the fimbria-induced expression of IL-1β and TNF-α genes in the cells. However, such inhibitory action was not observed with laminin treatment. These results suggest the importance of β₂ integrin (CD11/CD18) as a cellular receptor of P. gingivalis fimbriae in the initiation stage of the pathogenic mechanism of the organism in periodontal disease.     

The kinetics of surface expression of CD11/CD18 integrins and CD54 on monocytes and macrophages.

Cells of the macrophage lineage mediate extremely important normal functions of the immune system. Such functions are in part related to interactions between cell-bound LeuCAMs and their ligands. MoAb staining and flow cytometric analysis were used to follow changes in surface expression of LeuCAMs and the LFA-1 ligand CD54 during maturation of peripheral blood monocytes (BM) in vitro. Surface expression of these molecules increased on BM following isolation, the greatest increase being in CD54 and CD11c. Following an initial increase, there was a reduction in CD11a expression after 2 weeks in culture, this being greater on adherent compared with suspension-maintained cells. Expression of CD11b remained high throughout the culture period. LeuCAM and CD54 expression was further compared on freshly isolated alveolar macrophages (AM) and BM paired donors. A reciprocal relationship was observed between CD11c and CD11b on AM and BM, in that BM expressed higher levels of CD11b than CD11c, whilst the converse was true for AM. CD54 expression was also higher on AM than on BM, whilst there was no significant difference in expression of CD11a on these cells. These data suggest that consistent changes occur in the surface expression of the LeuCAMs and CD54 as monocytes mature into macrophages, which may reflect the specific functions of these cells.