Levels Of Lymphocyte Function-associated Antigen-1 Research Articles

Identification of neutrophil \u03b22-integrin LFA-1 as a potential mechanistic biomarker in ANCA-associated vasculitis via microarray and validation analyses

BackgroundLeukocyte activation by anti-neutrophil cytoplasmic antibody (ANCA) and the subsequent leukocyte–endothelium interaction play a key role in the development of endothelial damage in ANCA-associated vasculitis (AAV). In contrast to that of leukocyte activation, the exact role of the leukocyte–endothelium interaction via integrin remains unclear. Here, we performed microarray and validation analyses to explore association between the expression levels of lymphocyte function-associated antigen-1 (LFA-1) and the clinical characteristics of patients with AAV.MethodsWe performed gene set enrichment analysis (GSEA) to identify the functional gene sets differentially expressed between patients with AAV and other types of vasculitis and the healthy controls (HCs). Flow cytometry was performed to validate the GSEA results. Treatment-naïve patients were monitored until 24 weeks of treatment. To examine the role of LFA-1 in the neutrophil–endothelium interaction, we performed a leukocyte adhesion and transmigration assay using peripheral blood and human umbilical vein endothelial cells (HUVECs).ResultsGSEA revealed that the molecular pathways involving integrin-related genes were significantly upregulated in patients with AAV compared to that in patients with other types of vasculitis and the HCs. Flow cytometry revealed that the percentage of neutrophils expressing LFA-1 was significantly higher in patients with AAV than in those with large-vessel vasculitis or polyarteritis nodosa and the HCs. LFA-1 levels in the neutrophils were higher in patients with MPO-ANCA-positive expression than in those with a positive PR3-ANCA expression and correlated with the peripheral eosinophil count, serum rheumatoid factor titre, serum C-reactive protein levels, and the vasculitis activity score of systemic and chest components. After 24 weeks of treatment, including prednisolone, cyclophosphamide, rituximab, azathioprine, methotrexate, and/or tacrolimus, neutrophil LFA-1 expression remained high in the non-responder patients, but decreased in the responder patients. The in vitro assay showed that leukocyte migration toward HUVECs was dependent on the interaction between LFA-1 and intercellular adhesion molecule-1 (ICAM1); the migration of leukocytes was inhibited by blocking the adhesion of LFA-1 to ICAM1.ConclusionsThe expression of LFA-1 in neutrophils is increased in patients with AAV. Neutrophil LFA-1 levels correlate with the clinical features of AAV. Inhibiting the adhesion of LFA-1 and ICAM1 impedes the neutrophil–endothelium interaction and may have a therapeutic role in AAV.

Polyamine-Rich Diet Elevates Blood Spermine Levels and Inhibits Pro-Inflammatory Status: An Interventional Study.

The Japanese diet and the Mediterranean diet are rich in polyamines (spermidine and spermine). Increased polyamine intake elevated blood spermine levels, inhibited aging-associated pro-inflammatory status (increases in lymphocyte function-associated antigen-1 (LFA-1) on immune cells), suppressed aberrant gene methylation and extended the lifespan of mice. To test the effects of increased polyamine intake by humans, 30 healthy male volunteers were asked to eat polyamine-rich and ready-to-eat traditional Japanese food (natto) for 12 months. Natto with high polyamine content was used. Another 27 male volunteers were asked not to change their dietary pattern as a control group. The volunteers’ age of intervention and control groups ranged from 40 to 69 years (median 48.9 ± 7.9). Two subjects in the control group subsequently dropped out of the study. The estimated increases in spermidine and spermine intakes were 96.63 ± 47.70 and 22.00 ± 9.56 µmol per day in the intervention group, while no changes were observed in the control group. The mean blood spermine level in the intervention group gradually rose to 1.12 ± 0.29 times the pre-intervention level after 12 months, and were significantly higher (p = 0.019) than those in the control group. Blood spermidine did not increase in either group. LFA-1 on monocytes decreased gradually in the intervention group, and there was an inverse association between changes in spermine concentrations relative to spermidine and changes in LFA-1 levels. Contingency table analysis revealed that the odds ratio to decrease LFA-1 by increased polyamine intake was 3.927 (95% CI 1.116–13.715) (p = 0.032) when the effect of acute inflammation was excluded. The results in the study were similar to those of our animal experiments. Since methylation changes of the entire genome are associated with aging-associated pathologies and our previous studies showed that spermine-induced LFA-1 suppression was associated with the inhibition of aberrant gene methylation, the results suggest that dietary polyamine contributes to human health and longevity.

Endocan (ESM-1) levels in gingival crevicular fluid correlate with ICAM-1 and LFA-1 in periodontitis.

Endocan, a 50 kDa soluble proteoglycan, also called endothelial cell-specific molecule-1 (ESM-1), is involved in many major cellular activities and has been reported to be overexpressed in inflammatory conditions. This study aims to determine ESM-1 levels in gingival crevicular fluid (GCF) samples from individuals with periodontitis to determine the correlation between the levels of lymphocyte-function-associated antigen-1 (LFA-1), intercellular adhesion molecule-1 (ICAM-1), and clinical findings of periodontitis. This study enrolled 27 individuals diagnosed with Stage III-Grade C generalized periodontitis and 16 individuals as healthy controls. Bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment loss (CAL) were calculated. Enzyme-linked immunosorbent assay (ELISA) test was used for detecting the levels of ESM-1, ICAM-1, and LFA-1 in GCF samples. PPD, BOP, CAL, and GCF volumes were significantly increased in patients with periodontitis in comparison to the control group (p < 0.001). The total amount of ESM-1, ICAM-1, and LFA-1 levels in GCF were increased in the periodontitis group (p < 0.001). ESM-1 level correlated with PPD, BOP, and CAL (p < 0.05). ICAM-1 level correlated with BOP and CAL (p < 0.05). LFA-1 level correlated with PPD and CAL (p < 0.05). Our data indicate that ESM-1, ICAM-1, and LFA-1 levels are increased in GCF of patients with periodontitis. These molecules could be associated with the pathogenesis and progression of periodontal disease.

Regulation of LOX-1 on adhesion molecules and neutrophil infiltration in mouse Aspergillus fumigatus keratitis.

To determine whether lectin-like ox-LDL receptor (LOX-1) regulates adhesion molecules expression and neutrophil infiltration in Aspergillus fumigatus (A. fumigatus) keratitis of C57BL/6 mice. C57BL/6 mice were pretreated with a neutralizing antibody to LOX-1 (5 µg/5 µL) or control nonspecific IgG (5 µg/5 µL), LOX-1 inhibitor Poly-I (2 µg/5 µL) or PBS by subconjunctival injection. Fungal keratitis (FK) mouse models of C57BL/6 mice were established by scraping corneal central epithelium, smearing A. fumigatus on the corneal surface and covering the eye with contact lenses. The corneal response to infection was assessed via clinical score. The mRNA levels of the adhesion molecules intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), P-selectin and E-selectin were tested in control and infected corneas by reverse transcription-polymerase chain reaction (RT-PCR). The protein levels of ICAM-1 were evaluated by immunofluorescence (IF) and Western blot. Neutrophils were extracted from the abdominal cavity of C57BL/6 mice followed by pretreatment using antibody to LOX-1 (10 µg/mL) or control nonspecific IgG (10 µg/mL), the Poly-I (4 µg/mL) or PBS. The cells were then stimulated with A. fumigatus and tested mRNA and protein levels of lymphocyte function-associated antigen-1 (LFA-1) using RT-PCR and Western blot. IF and myeloperoxidase (MPO) assays were used to assess neutrophil infiltration in mice corneas. Pretreatment of LOX-1 antibody or the Poly-I reduced the degree of inflammation of cornea and decreased the clinical FK score compared with pretreatment of IgG or PBS (both P<0.01). And these pretreatment also displayed an obvious decline in the mRNA levels of ICAM-1, VCAM-1, P-selectin, E-selectin and LFA-1 expression compared with control groups (all P<0.01). Furthermore, pretreated with LOX-1 antibody or Poly-I, the protein levels of ICAM-1 and LFA-1 also decreased compared with control groups (all P<0.05). Neutrophil infiltration in the cornea was significantly reduced after pretreatment of LOX-1 antibody or Poly-I compared with control groups by IF and MPO assays (both P<0.01). Inhibition of LOX-1 can decrease the expression of adhesion molecules and reduce neutrophil infiltration in A. fumigatus infected corneas of C57BL/6 mice.

Salivary Del-1, IL-17, and LFA-1 levels in periodontal health and disease.

Developmental endothelial locus-1 (Del-1), lymphocyte function-associated antigen-1 (LFA-1), and interleukin 17 (IL-17) play critical roles in transendothelial migration of neutrophils in periodontal diseases. The aim of this study was to evaluate salivary Del-1, IL-17, and LFA-1 protein levels in patients with gingivitis (G), chronic periodontitis (CP), and generalized aggressive periodontitis (GAP). A total of 180 systemically healthy, non-smoking patients (45 periodontally healthy (H) and 45 G, 50 CP, and 40 GAP) individuals (between March 2014 and February 2016) were included in this study according to Armitage's (1999) classification. Clinical periodontal parameters, including clinical attachment level, probing depth, plaque index, and gingival index, were recorded. Del-1, IL-17, and LFA-1 protein expression levels were measured in unstimulated saliva samples collected from patients by using enzyme-linked immunosorbent assays. Kruskal-Wallis and Mann-Whitney U tests were used for multiple comparisons and post hoc statistical analyses, respectively. ROC curve analysis was used to evaluate the sensitivity and specificity of Del-1, IL-17, and LFA-1 in distinguishing periodontal disease from health and gingivitis. It was found a high level of IL-17 and a low level of Del-1 in the CP and GAP, as compared to the G and H groups (P<.001). Nevertheless, we found LFA-1 levels were higher in the GAP than in the CP or G groups (P=.00). Consistently, LFA-1 levels were lower in the H and G groups than in the CP and GAP groups (P=.00). The combination of three biomarkers was found as the best predictor yielded exhibited the highest AUC [0.893, 0.845-0.94 (%95 CI) P<.001] in discriminating periodontal disease from health and gingivitis. Salivary Del-1, LFA-1, and IL-17 levels might be useful markers for determining the clinical health and disease status of patients with periodontitis. However, further studies that evaluate the level of salivary Del-1, LFA-1, and IL-17 before and after periodontal therapy are required to understand the exact roles of these cytokines during the periodontal healing period.

Effect of aerobic exercise on blood lipid and ICAM-1, LFA-1 in hyperlipidemia rats

Objective To observe aerobic exercise on blood lipid and intercellular adhesion molecule-1 (ICAM-1), lymphocyte function-associated antigen-1 (LFA-1) in hyperlipidemia rats. Methods 120 male Sprague Dawley (SD) rats were randomized into the 4 groups (n=30): normal diet group (control group), high fat group (HF group), HF+ SBC-115076 group [SBC-115076, 8 mg/kg·w)] and HF+ aerobic exercise group. Rats in HF group and HF+ SBC-115076 group did not exercise during feeding and lived in normal cage. Rats in HF+ SBC-115076 group recieved PCSK9 inhibitor SBC-115076 (8 mg/kg) injection once a week for 8 weeks. HF+ aerobic exercise group underwent load-free swimming training 6 days a week for 8 weeks. The rats were sacrificed 8 weeks later. The serum levels of triglyceride (TG), total cholesterol (TC), low density lipoprotein (LDL), high density lipoprotein (HDL), ICAM-1 and LFA-1 were measured by apical blood sampling. Hematoxylin-eosin (HE) staining of thoracic aorta to observe pathological changes of aorta. Results After modeling, there was no significant difference in the food intake levels of the hyperlipidemia rats (P>0.05). The body weight of HF rats and HF+ SBC-115076 rats increased significantly than HF+ aerobic exercise rats (P<0.01). The levels of serum lipid profile, ICAM-1, and LFA-1 were significantly different between HF rats and control rats. Compared with HF rats, serum levels of TG, TC, LDL, ICAM-1 and LFA-1 in HF+ SBC-115076 group and HF+ aerobic exercise group were significantly lower and HDL levels were significantly higher. HE staining showed that the intimal thickening was significantly improved in HF+ aerobic exercise group with less endothelial damage. Conclusions Aerobic exercise can reduce the levels of serum TG, TC, LDL and increase HDL level in rats with hyperlipidemia. It can improve the intimal thickening and endothelial damage caused by high-fat diet by reducing the expression levels of serum ICAM-1 and LFA-1, and has anti-atherosclerosis effect. Key words: Exercise; Hyperlipidemias; Intercellular adhesion molecule-1; Lymphocyte function-associated antigen-1; Rats

Dysregulation of endothelial cell specific molecule-1 expression during urosepsis-induced acute lung injury in rabbits

Objective To explore the expression of endothelial cell specific molecule-1 (ESM-1) and inflammatory factors during urosepsis-induced acute lung injury (ALI) in rabbits, and the potential mechanism. Methods Urosepsis-induced ALI models in rabbits were assigned into three groups: control group, sham group and urosepsis group (0, 6, 12 and 36 h according to time points pre-scheduled). The rabbit urosepsis model was established by artificial high pressure in the infected pelvis. Lung histomorphological changes were observed by light microscope. The levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, ESM-1, lymphocyte function associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) in serum were analyzed by enzyme linked immunosorbent assay (ELISA). The expression of ESM-1, LFA-1 and ICAM-1 in serum was detected by ABC immunohistochemistry, and further the ESM-1/LFA-1 rate in lung tissue was calculated. Results As compared with the control group and sham group, urosepsis group had serious lung injury. The levels of serum TNF-α, IL-1β and IL-6 were elevated significantly in urosepsis group. After 6, 12, 24 and 36 h, the levels of TNF-α were (63.65±3.07), (128.17±4.26), (99.24±7.97), (49.36±6.09) ng/L; the levels of IL-1β were (232.77±21.54), (481.21±20.84), (220.23±22.21), (105.25±23.46) ng/L; the levels of IL-6 were (72.62±4.42), (122.51±6.77), (82.22±4.23), (60.05±2.82) ng/L. The expression levels in the urosepsis group were significantly higher than those in the control group and the sham group at each time point (After 36 h, TNF-α: F=96.932, P=0.000; IL-1β: F=9.001, P=0.007; IL-6: F=5.293, P=0.030). The expression of serum LFA-1 and ICAM-1 was increased over time in urosepsis group. After 6, 12, 24 and 36 h, the levels of LFA-1 were (12.50±5.71), (23.16±6.84), (45.04±7.65), (61.38±9.87) ng/L; the levels of ICAM-1 were (780.67±66.89), (1 034.16±72.33), (1 420.10±87.25), (1 834.23±88.46) ng/L, which were significantly different from those in the control group and the sham group (After 36 h, LFA-1: F=85.612, P=0.000; ICAM-1: F=456.901, P=0.000). Meantime, the levels of ESM-1 expression and ESM-1/LFA-1 rate in the lung tissue during urosepsis increased in the early stage of urosepsis but declined over time. The levels of LFA-1 were: 0.139±0.017, 0.274±0.024, 0.120±0.035, 0.089±0.031; the ESM-1/LFA-1 rate was: 1.188±0.019, 1.473±0.015, 0.529±0.020, 0.263±0.017, which were significantly different from those in the control group and the sham group (After 36 h, ESM-1: F=13.190, P=0.002; ESM-1/LFA-1: F=891.411, P=0.000). Conclusion The expression changes of ESM-1 may suggest the development process during urosepsis-induced ALI. The present study may offer beneficial reference for treating ALI, and decreasing multiple organs failure in earlier phase clinically. Key words: Endothelial cell specific molecule-1; Lymphocyte function associated antigen-1/Intercellular adllesion molecule-1; Urosepsis; Acute lung injury

Identification of an intercellular cell adhesion molecule-1 homologue from grass carp: Evidence for its involvement in the immune cell adhesion in teleost

Intercellular cell adhesion molecule-1 (ICAM-1) is a single-chain transmembrane glycoprotein which plays key roles in transendothelial migration of leukocytes and interaction between antigen presenting cells and T cells. In teleost, information of cell adhesion-related molecules is still lacking. In this study, we identified a gene from grass carp sharing similar exon and intron organization with human ICAM-1. Cloning and in silico analysis of its homologues in zebrafish and other two cyprinid fishes, respectively demonstrated the existence of the gene in these fishes. Moreover, the molecular features of these genes in fishes were conserved compared with human ICAM-1. In grass carp, the transcripts of this gene were detected with high levels in heart and liver and its mRNA expression in headkidney leukocytes was induced by Il-1β. Overexpression of this molecule in COS-7 cells could increase the adhesion of the cells with grass carp peripheral blood lymphocytes (PBLs), and the adhesion was further enhanced by lipopolysaccharide stimulation on PBLs. Further studies revealed that the mRNA levels of lymphocyte function-associated antigen-1, a ligand for ICAM-1, were much higher in the PBLs adhering to the COS-7 cells with overexpressing this molecule than in the PBLs alone. These results collectively showed that the newly cloned cDNA encodes grass carp intercellular cell adhesion molecule-1 (Icam-1) and it can mediate the adhesion of PBLs. This provides functional evidence for the existence of Icam-1 in teleost and will facilitate investigation on the transendothelial migration of leukocytes in fish species.

The interaction of dendritic cells and γδ T cells promotes the activation of γδ T cells in experimental autoimmune uveitis

Uveitis is a severe inflammatory disease that can cause visual impairment. Recently, activated [Formula: see text] T cells were proved to play a central role in the development of experimental autoimmune uveitis (EAU). However, the mechanism underlying [Formula: see text] T-cell activation in EAU is incompletely known. In this study, we determined the percentage changes in and the phenotypes of [Formula: see text] T cells and dendritic cells (DCs) obtained from the spleens of immunized C57BL/6 (B6) mice, an animal model of EAU. We found that the number of [Formula: see text] T cells and DCs obviously increased during the inflammation phase of EAU (days 16–20 of our experiment), and that during this time, [Formula: see text] T cells expressed high levels of CD69 and the integrin lymphocyte function–associated antigen-1 (LFA-1) and secreted high levels of interleukin (IL)-17A. Moreover, DCs obtained during this phase expressed high levels of CD80, CD83, CD86, and intracellular cell adhesion molecule-1 (ICAM-1). Furthermore, we studied the interaction between DCs and [Formula: see text] T cells by using flow cytometry and confocal microscopy in order to determine whether DCs affected [Formula: see text] T-cell activation in vitro. Co-cultures of the two types of cells showed that DCs induced high levels of CD69, LFA-1, and IL-17A in [Formula: see text] T cells. Imaging studies revealed contact between the DCs and [Formula: see text] T cells. This interaction was mediated by the accumulation of ICAM-1 and LFA-1 at the interface of DCs-[Formula: see text] T cells. Thus, the activation of [Formula: see text] T cells in EAU was promoted by DCs interacting with [Formula: see text] T cells.

Mechanisms of LtxA (Leukotoxin), a Potent New Anti-Inflammatory Agent for the Treatment of Alopecia Areata.

Alopecia areata is an autoimmune condition where activated, pro-inflammatory white blood cells (WBCs) attack the hair follicles, resulting in hair loss. Migration of these activated WBCs from the blood stream and into the follicle tissue requires interaction between the integrin, lymphocyte function-associated antigen-1 (LFA-1) on WBCs, and ICAM-1 on vascular endothelial cells. High levels of active LFA-1 are uniquely expressed on WBCs that are involved in autoimmune and inflammatory conditions. The natural biologic agent LtxA (Leukothera) preferentially targets and depletes disease activated and malignant WBCs by binding to active LFA-1. The experimental drug has demonstrated significant therapeutic efficacy against autoimmune/inflammatory conditions such as psoriasis and allergic asthma in mouse models for these diseases. In addition, when injected into rodents, rhesus macaques, and dogs, LtxA was demonstrated to be physiologically active, biologically specific, and extremely well-tolerated. LFA-1 is an attractive target for therapy because it is only normally present on WBCs and has been shown to be activated and overexpressed on WBCs that are responsible for autoimmune/inflammatory conditions.

Expression and targeting of lymphocyte function-associated antigen 1 (LFA-1) on white blood cells for treatment of allergic asthma.

Allergic asthma is a chronic respiratory disease that results from an exaggerated inflammatory response in the airways. Environment stimuli, such as pollen and HDM, cause activation and migration of inflammatory WBCs into the respiratory tract, where they cause lung damage. Migration of these WBCs is dependent on the active configuration of the β2 integrin LFA-1. The experimental therapeutic agent LtxA specifically targets active LFA-1 and causes cell death. We investigated the association between LFA-1 and allergic asthma and hypothesized that targeting LFA-1 with LtxA could be an attractive strategy for treatment of the condition. We examined LFA-1 (CD11a) levels on PBMCs from patients with allergic asthma compared with healthy controls. Patients exhibited a significantly higher percentage of PBMCs expressing LFA-1 than healthy controls. Furthermore, the level of LFA-1 expression on patient PBMCs was greater than on healthy PBMCs. We identified a unique cellular population in patients that consisted of CD4(-) CD11a(hi) cells. We also evaluated LtxA in a HDM extract-induced mouse model for allergic asthma. LtxA caused resolution of disease in mice, as demonstrated by a decrease in BALF WBCs, a reduction in pulmonary inflammation and tissue remodeling, and a decrease in proinflammatory cytokines IL-4, IL-5, IL-9, IL-17F, and IL-23α in lung tissue. LFA-1 may serve as an important marker in allergic asthma, and the elimination of activated WBCs by use of LtxA could be a viable therapeutic strategy for treating patients with this condition.

Fas Ligand-Dependent Inflammatory Regulation in Acute Myocarditis Induced by Trypanosoma cruzi Infection

Fas/Fas ligand (Fas-L) engagement, a potent inducer of apoptosis, is also important for cellular activation, regulation of effector and chemotactic activity, and secretion of chemokines and cytokines. We evaluated the relevance of Fas/Fas-L in the regulation of myocarditis induced by Trypanosoma cruzi infection and observed that in Fas-L(-/-) mice (gld/gld), cardiac infiltration was significantly reduced, accordingly showing less cardiomyocyte destruction. Fluorescence-activated cell sorting analysis of cardiac inflammatory cells showed higher numbers of CD8(+) T cells in BALB/c compared with gld/gld mice but similar levels of lymphocyte function-associated antigen-1, intercellular adhesion molecule, CD2, and CD69 expression; MAC-1(+) myeloid cells and mast cells were increased in BALB/c mice, whereas gld/gld mice exhibited an enrichment of CD4(+/low) T cells. Intracellular labeling of cytokines revealed no clear cardiac skewing of Th1 or Th2 responses, but we found a higher number of interleukin-10(+) cells in gld/gld mice and a deficient expression of vascular cell adhesion molecule-1 on cardiac endothelial cells in gld/gld mice. Finally, we found a population of CD3(+) but CD4/CD8 double negative cardiac T cells in both groups of infected mice, but down-regulation of some adhesion molecules and surface receptors was only observed in gld/gld mice, indicating a targeted T-cell population mostly affected by the lack of Fas-L engagement. These results point to a role for myocarditis regulation by Fas/Fas-L beyond its possible direct relevance in cellular death.

Mycobacterium tuberculosis-infected human macrophages exhibit enhanced cellular adhesion with increased expression of LFA-1 and ICAM-1 and reduced expression and/or function of complement receptors, FcgammaRII and the mannose receptor.

The entry of Mycobacterium tuberculosis (Mtb) into the host macrophage and its survival in this environment are key components of tuberculosis pathogenesis. Following intracellular replication of the bacterium within alveolar macrophages, there is spread of bacilli to regional lymph nodes in the lungs and subsequent presentation of antigens to the host immune system. How this process occurs remains poorly understood, but one mechanism may involve the migration of macrophages containing Mtb across the alveoli to lymph nodes, where there is development of a protective host response with formation of granulomas composed in part of aggregated and fused, apoptotic, infected macrophages. Leukocyte integrins, including lymphocyte function-associated antigen-1 (LFA-1) and complement receptors CR3 and CR4, and their counter receptors play a major role in macrophage adhesion processes and phagocytosis. In this study, the appearance of Mtb-infected macrophages over time was examined, using inverted-phase microscopy and an in vitro culture model of human monocyte-derived macrophages (MDMs). Prior to and immediately following infection of the MDMs with Mtb, the macrophages appeared as individual cells in monolayer culture; however, within 24 h of infection with Mtb, the MDMs began to migrate and adhere to each other. The kinetics of this response were dependent on both the m.o.i. and the length of infection. Quantitative transmission electron microscopy studies revealed that macrophage adhesion was accompanied by increases in levels of LFA-1 and its counter receptor (ICAM-1), decreases in surface levels of the phagocytic receptors CR3, CR4 and FcgammaRII, and an increase in major histocompatibility complex Class II (MHC-II) molecules at 72 h post-infection. Decreases in surface levels of CR3 and CR4 had a functional correlate, with macrophages containing live bacilli showing a diminished phagocytic capacity for complement-opsonized sheep erythrocytes; macrophages containing heat-killed bacilli did not show this diminished capacity. The modulation of macrophage adhesion and phagocytic proteins may influence the trafficking of Mtb-infected macrophages within the host, with increases in levels of LFA-1 and ICAM-1 enhancing the adhesive properties of the macrophage and decreases in phagocytic receptors diminishing the phagocytic capacity of an already-infected cell, potentially allowing for maintenance of the intracellular niche of Mtb.

Cytokine Expression and Tumorigenicity of Large Granular Lymphocytic Leukemia Cells From Mice Transgenic for the tax Gene of Human T-Cell Leukemia Virus Type I

AbstractThe human T-cell leukemia virus type I (HTLV-I) regulatory protein, Tax, has been speculated to play a major role in HTLV-I leukemogenesis. Indeed, several studies have suggested that upregulation of various cellular oncogenes and cytokines by Tax may explain the pathogenesis observed in HTLV-I–infected individuals, as well as several Tax-transgenic animal models. We report here the analysis of cytokine expression in a Tax-transgenic animal model with large granular lymphocytic (LGL) leukemia. Two different transgenic mice showed identical expression of interleukin-1α (IL-1α), IL-1β, interferon γ (IFNγ), and granulocyte-macrophage colony-stimulating factor (GM-CSF ) in peripheral tail tumors. Interestingly, LGL cell lines derived from these same tumors expressed high levels of both IFNγ and GM-CSF, which correlated with the level of Tax expression. These same LGL cell lines also expressed high levels of lymphocyte function-associated antigen-1 (LFA-1) and intracellular adhesion molecule-1 (ICAM-1). Engraftment of these LGL cell lines into severe combined immunodeficient (SCID) mice led to the development of leukemia and lymphomas. Examination of these SCID mice showed that their pathology was nearly identical to that observed in the original Tax-transgenic mouse model. Both the Tax-transgenic and engrafted SCID mouse models allow for the analysis of cellular events that are required for tumor development associated with HTLV infection and suggest that Tax expression may be responsible for the upregulation of certain cytokines and adhesion molecules that affect the infiltrating capabilities of HTLV-I–infected cells.

Cytokine Expression and Tumorigenicity of Large Granular Lymphocytic Leukemia Cells From Mice Transgenic for the tax Gene of Human T-Cell Leukemia Virus Type I

The human T-cell leukemia virus type I (HTLV-I) regulatory protein, Tax, has been speculated to play a major role in HTLV-I leukemogenesis. Indeed, several studies have suggested that upregulation of various cellular oncogenes and cytokines by Tax may explain the pathogenesis observed in HTLV-I–infected individuals, as well as several Tax-transgenic animal models. We report here the analysis of cytokine expression in a Tax-transgenic animal model with large granular lymphocytic (LGL) leukemia. Two different transgenic mice showed identical expression of interleukin-1α (IL-1α), IL-1β, interferon γ (IFNγ), and granulocyte-macrophage colony-stimulating factor (GM-CSF ) in peripheral tail tumors. Interestingly, LGL cell lines derived from these same tumors expressed high levels of both IFNγ and GM-CSF, which correlated with the level of Tax expression. These same LGL cell lines also expressed high levels of lymphocyte function-associated antigen-1 (LFA-1) and intracellular adhesion molecule-1 (ICAM-1). Engraftment of these LGL cell lines into severe combined immunodeficient (SCID) mice led to the development of leukemia and lymphomas. Examination of these SCID mice showed that their pathology was nearly identical to that observed in the original Tax-transgenic mouse model. Both the Tax-transgenic and engrafted SCID mouse models allow for the analysis of cellular events that are required for tumor development associated with HTLV infection and suggest that Tax expression may be responsible for the upregulation of certain cytokines and adhesion molecules that affect the infiltrating capabilities of HTLV-I–infected cells.

T-lymphocyte responsiveness in murine schistosomiasis mansoni is dependent upon the adhesion molecules intercellular adhesion molecule-1, lymphocyte function-associated antigen-1, and very late antigen-4

Granuloma formation in murine schistosomiasis is dependent on CD4+ Th lymphocytes and requires recruitment and accumulation of inflammatory cells at the site of egg deposition. The present study examined the role of three adhesion molecules, intercellular adhesion molecule-1 (ICAM-1), lymphocyte function-associated antigen-1 (LFA-1), and very late antigen-4 (VLA-4), that participate in cellular recruitment, interaction, and lymphocyte activation during in vitro activation of acutely and chronically infected spleen and liver granuloma lymphocytes. Blockade of ICAM-1, LFA-1, or VLA-4 by rat monoclonal antibody inhibited spleen and granuloma lymphocyte interleukin-2 (IL-2) and IL-4 production as well as lymphoproliferative responses at similar levels (66 to 87%). The down-modulated cytokine and proliferative responses of chronically infected lymphocytes were inhibited to the same extent as their acutely infected counterparts. Cell sorting analysis demonstrated that acutely and chronically infected splenic and granuloma lymphocytes expressed similar levels of LFA-1, ICAM-1, and VLA-4 and that more ICAM-1 was expressed on infected than on uninfected mouse lymphocytes. By exposure of cells to paired monoclonal antibodies at suboptimal doses, it was determined that whereas all three adhesion molecules may participate, only ICAM-1 and LFA-1 showed synergistic interactions in determining lymphocyte responsiveness. These data suggest that spleen and liver granuloma lymphocytes are equally well armed with functional adhesion receptors. Thus, ICAM-1, LFA-1, and VLA-4 play an important accessory role in inflammatory cytokine production and lymphocyte proliferation, and therefore these adhesion molecules may participate in the initiation and maintenance of the granulomatous inflammation.

Role of adhesion molecules in the lymphoid cell distribution in rheumatoid synovial membrane

We studied the staining pattern of a group of adhesion molecules in the lining layer and lymphocytic infiltrates of the rheumatoid synovial membrane, using monoclonal antibodies against lymphocyte function associated antigen-1 (LFA-1), very late activation antigen-4 (VLA-4), VLA-5, endothelial leucocyte adhesion molecule-1 (ELAM-1) and intercellular adhesion molecule-1 (ICAM-1). The cells of the the lining layer were strongly ICMA-1 positive and VLA-5 positive, suggesting (1) that ICAM-1 may function to facilitate the adhesion of ICAM-1-bearing type A cells to type B lining cells and (2) that the lining cells may utilize VLA-5 for anchorage to fibronectin at the surface of the synovial membrane. In the lymphocyte-rich and transitional areas, the endothelial cells of the postcapillary venules were both ELAM-1 positive and ICAM-1 positive. ICAM-1 staining was weak in lymphoid aggregates, but strong in the transitional areas, indicating a paucity of ICAM-1-bearing cells in the lymphocyte-rich areas. On the other hand, LFA-1 staining was very strong in the lymphoid aggregates and only moderate in transitional areas. This suggested that the large numbers of T4 cells present in the lymphocyte-rich areas are sufficiently activated to express substantial levels of LFA-1, and also that the LFA-1 molecule is an important receptor for emigration from postcapillary venules. In germinal centre like areas in lymphoid aggregates, most of the cells stained strongly for ICAM-1 and VLA-4, suggesting that the proliferation of B lymphocytes may be facilitated by LFA-1- and VLA4-dependent T and B cell interaction. The VLA molecules stained in the transitional areas may provide appropriate adhesion and anchorage of lymphocytes for the achievement of the variety of immune reactions in which these cells are engaged in these areas.

Age-related changes in LFA-1 expression, cell adhesion, and PHA-induced proliferation by lymphocytes from senescence-accelerated mouse (SAM)-P/8 and SAM-R/1 substrains

Accelerated senescence-prone mice of the SAM-P/8 jf series were compared with senescenceresistant SAM-R/1 controls in terms of age-related changes in phytohemagglutinin (PHA) proliferative responses and lymphocyte function-associated antigen-1 (LFA-1) utilization by nonadherent splenocytes. Advancing age was associated with a reduction in cell proliferative responses to PHA in both substrains, although the rate of decline was significantly more rapid in the senescence-prone animals. Conversely, in both substrains there was a progressive age-related increase in the proportion of splenocytes expressing high levels of LFA-1, and a parallel increase in the degree of LFA-1-dependent cell aggregation induced by phorbol ester. Age-matched SAM-P/8 jf and SAM-R/1 mice did not differ in terms of LFA-1 expression or LFA-1-dependent cell aggregation. Two-color cytofluorometric analysis demonstrated the enhanced expression of LFA-1 expression by cells bearing the Pgp-1 hi phenotype characteristic of memory lymphocytes. These results suggest that age-associated changes in lymphocyte adhesion are attributable to alterations in the relative numbers of memory cells expressing high levels of LFA-1, but are unlikely to contribute to the reduced proliferative response to mitogen in aged mice.

Differential Expression of Lymphocyte Function-Associated Antigen 1(LFA-1) on Epidermotropic and Non-Epidermotropic T-Cell Clones

Various T-cell surface molecules are involved in T-cell adhesion, which is an essential requirement for epidermotropic migration of T cells. Our previous studies demonstrated that certain T-cell clones can migrate into the epidermis upon their intradermal inoculation into the footpads of recipient mice with relevant antigens, while other T-cell clones, despite their identical antigen specificities and functions, are non-epidermotropic. We therefore tested whether the differences in epidermotropism of these T cells could reside in the different levels of expression of T-cell surface molecules such as CD3, CD4, CD2, and lymphocyte function associated antigen 1 (LFA 1). The results of flow cytometric analysis showed that LFA-1 was preferentially expressed on the surface of epidermotropic T-cell clones, while non-epidermotropic T-cell clones were negative or very weakly positive for LFA-1 with one exception. After exposure to phorbol ester, epidermotropic clones with high levels of LFA-1 did not show any further up-regulation of LFA-1. In contrast, under identical conditions, significant up-regulation of LFA-1 was observed on non-epidermotropic T cells with low levels of LFA-1. However, even after exposure to phorbol ester, these T cells remained non-epidermotropic. These results suggest that the presence of high levels of LFA-1 on T cells is absolutely necessary for their epidermotropic migration, but its up-regulation is neither necessary nor sufficient to trigger the epidermotropic migration. High levels of LFA-1, regardless of cell activation, may be required to mediate stable cell adhesions leading to epidermotropic migration.

Higher level expression of lymphocyte function-associated antigen-1 (LFA-1) on in vivo natural killer cells.

Normal mouse spleen cells express low levels of lymphocyte function-associated antigen-1 (LFA-1) as well as other lymphoid cells. However, fractionation of spleen cells with Percoll discontinuous gradients resulted in the appearance of lymphocytes expressing high levels of LFA-1 molecule (LFA-1 high lymphocytes) in parallel with the enrichment of natural killer (NK) activity. Lower density spleen cells (fractions 1 and 2) expressed higher level of LFA-1 antigen than unfractionated spleen cells and showed a higher NK activity. In contrast, higher density spleen cells (fractions 3 and 4) expressed lower levels of LFA-1 antigen and revealed lower NK activity. LFA-1 high lymphocytes possessed a high level of asialo GM1, which was the cell surface marker for NK cells. Moreover, sorting of LFA-1 high lymphocytes from spleen cells caused a great enrichment of NK cells. These results demonstrated that in vivo NK cells expressed higher levels of LFA-1 molecule, which was an important adhesion molecule for NK cell-mediated cytotoxicity.