Augmented expression and release of nonspecific cross-reacting antigens (NCAs), members of the CEA family, by human neutrophils during cell activation

Elevation of neutrophil carcinoembryonic antigen-related cell adhesion molecule 1 associated with multiple inflammatory mediators was related to different clinical stages in ischemic stroke patients

BACKGROUND

We aimed to analyze the level of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) in neutrophils of ischemic stroke (IS) patients at different stages, together with its roles in neutrophils.

PATIENTS AND METHODS

Sixty-seven patients were classified into acute phase group (n = 19), subacute phase group (n = 28), and stable phase group (n = 20), and 20 healthy individuals who had received physical examination at the same time period as healthy control. We then analyzed the expression level of CEACAM1 and cell viability in CEACAM1 positive and CEACAM1 negative neutrophils by flow cytometry and the content of plasma CEACAM1, neutrophil gelatinase-associated lipocalin (NGAL), matrix metalloproteinases-9 (MMP-9) was measured using enzyme-linked immunosorbent assay (ELISA), while that of interleukin-10 (IL-10) and tumor necrosis factor (TNF) was determined using a Human Enhanced Sensitivity Flex set.

RESULTS

Compared with healthy control, the percentage of CEACAM1 positive neutrophils in IS patients showed a significant increase, and a significant increase was also noticed in the content of plasma CEACAM1 at the subacute stage. Reduction in cell viability was observed in CEACAM1 positive neutrophils compared with CEACAM1 negative counterparts. There was a positive correlation between CEACAM1 expression rate in neutrophils and plasma CEACAM1 and IL-10 content in the subacute group. Compared with acute group and healthy control group, there was an instinct increase in the level of plasma MMP-9 and NGAL in subacute group.

CONCLUSIONS

Our data showed that there was a rapid increase of CEACAM1 in neutrophils at the acute stage of IS. We speculated that CEACAM1 may serve as an inhibitory regulator involving in the progression of IS.

T cell-mediated elimination of cancer cells by blocking CEACAM6–CEACAM1 interaction

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6), a cell surface receptor, is expressed on normal epithelial tissue and highly expressed in cancers of high unmet medical need, such as non-small cell lung, pancreatic, and colorectal cancer. CEACAM receptors undergo homo- and heterophilic interactions thereby regulating normal tissue homeostasis and angiogenesis, and in cancer, tumor invasion and metastasis. CEACAM6 expression on malignant plasma cells inhibits antitumor activity of T cells, and we hypothesize a similar function on epithelial cancer cells.

The interactions between CEACAM6 and its suggested partner CEACAM1 on T cells were studied. A humanized CEACAM6-blocking antibody, BAY 1834942, was developed and characterized for its immunomodulating effects in co-culture experiments with T cells and solid cancer cells and in comparison to antibodies targeting the immune checkpoints programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), and T cell immunoglobulin mucin-3 (TIM-3).

The immunosuppressive activity of CEACAM6 was mediated by binding to CEACAM1 expressed by activated tumor-specific T cells. BAY 1834942 increased cytokine secretion by T cells and T cell-mediated killing of cancer cells. The in vitro efficacy of BAY 1834942 correlated with the degree of CEACAM6 expression on cancer cells, suggesting potential in guiding patient selection. BAY 1834942 was equally or more efficacious compared to blockade of PD-L1, and at least an additive efficacy was observed in combination with anti-PD-1 or anti-TIM-3 antibodies, suggesting an efficacy independent of the PD-1/PD-L1 axis.

In summary, CEACAM6 blockade by BAY 1834942 reactivates the antitumor response of T cells. This warrants clinical evaluation.

Co-expression Network Analysis Elucidated a Core Module in Association With Prognosis of Non-functioning Non-invasive Human Pituitary Adenoma

Non-functioning pituitary adenomas (NFPAs) are tumors with clinically challenging features since they have insidious progression. A complex network of gene interactions is thought to have roles in tumor formation and progression. Therefore, revealing the genetic network behind NFPA tumorigenesis is not only essential to attain further knowledge of tumor biology, but also plays a fundamental role in the development of efficacious treatment strategies. Differential co-expression network analysis is an outstanding approach for elucidation of groups of genes which show distinct co-expression patterns among phenotypes. In this study, we carried out a differential co-expression network analysis of NFPA-associated transcriptome dataset (n = 40) considering invasive (n = 22) and non-invasive (n = 18) phenotypes. Furthermore, we identified differentially co-expressed and co-regulated mRNA modules, which might be considered as potential systems biomarkers for NFPA prognosis and invasiveness. As a result, we have identified a novel 13-gene module, including CEACAM6, CYP4B1, EIF2S2, HID1, IFFO1, MYO18A, PDCD2, SGIP1, SWSAP1, and four unknown genes (A_24_P127621, A_24_P255786, A_24_P683553, and A_24_P916979), which was able to categorize the patients into two groups as invasive and non-invasive NFPA with distinct prognosis. The prognostic core module genes were associated with progression and prognosis of brain and glandular based cancers as well. Furthermore, these module genes were also expressed in blood, salivary gland, and spinal cord tissues. These results may provide the evidence on featured gene module which might play a prominent role in NFPA prognosis and sub-typing as effective biomarkers and therapeutic targets in the future.

A CEACAM6-High Airway Neutrophil Phenotype and CEACAM6-High Epithelial Cells Are Features of Severe Asthma

Severe asthma represents a major unmet clinical need; understanding the pathophysiology is essential for the development of new therapies. Using microarray analysis, we previously found three immunological clusters in asthma: Th2-high, Th17-high, and Th2/17-low. Although new therapies are emerging for Th2-high disease, identifying molecular pathways in Th2-low disease remains an important goal. Further interrogation of our previously described microarray dataset revealed upregulation of gene expression for carcinoembryonic Ag cell adhesion molecule (CEACAM) family members in the bronchi of patients with severe asthma. Our aim was therefore to explore the distribution and cellular localization of CEACAM6 using immunohistochemistry on bronchial biopsy tissue obtained from patients with mild-to-severe asthma and healthy control subjects. Human bronchial epithelial cells were used to investigate cytokine and corticosteroid in vitro regulation of CEACAM6 gene expression. CEACAM6 protein expression in bronchial biopsies was increased in airway epithelial cells and lamina propria inflammatory cells in severe asthma compared with healthy control subjects. CEACAM6 in the lamina propria was localized to neutrophils predominantly. Neutrophil density in the bronchial mucosa was similar across health and the spectrum of asthma severity, but the percentage of neutrophils expressing CEACAM6 was significantly increased in severe asthma, suggesting the presence of an altered neutrophil phenotype. CEACAM6 gene expression in cultured epithelial cells was upregulated by wounding and neutrophil elastase. In summary, CEACAM6 expression is increased in severe asthma and primarily associated with airway epithelial cells and tissue neutrophils. CEACAM6 may contribute to the pathology of treatment-resistant asthma via neutrophil and airway epithelial cell-dependent pathways.

The role of CEA-related cell adhesion molecule-1 (CEACAM1) in vascular homeostasis

Carcinoembryonic antigen (CEA)-related cell adhesion molecules belong to the immunoglobulin superfamily, are expressed in a broad spectrum of tissues and cell types and exert context-dependent activating as well as inhibitory effects. Among these molecules, the CEA-related cell adhesion molecule-1 (CEACAM1) is a transmembrane molecule with an extracellular, a transmembrane and a cytoplasmic domain. The latter contains immunoreceptor tyrosine-based inhibitory motifs and functions as a signaling molecule. CEACAM1 can form homo- and heterodimers which is relevant for its signaling activities. CEACAM1 acts as co-receptor that modulates the activity of different receptor types including VEGFR-2, and B and T cell receptors. CEACAM1 is expressed in endothelial cells, in pericytes of developing and newly formed immature blood vessels and in angiogenically activated adult vessels, e.g., tumor blood vessels. However, it is either undetectable or only weakly expressed in quiescent blood vessels. Recent studies indicated that CEACAM1 is involved in the regulation of the endothelial barrier function. In CEACAM1 ^-/- mice, increased vascular permeability and development of small atherosclerotic lesions was observed in the aortae. CEACAM1 is also detectable in activated lymphatic endothelial cells and plays a role in tumor lymphangiogenesis. This review summarizes the vascular effects of CEACAM1 and focuses on its role in vascular morphogenesis and endothelial barrier regulation.

The Role of Biliary Carcinoembryonic Antigen-Related Cellular Adhesion Molecule 6 (CEACAM6) as a Biomarker in Cholangiocarcinoma

Objective

The aim of the present study is to determine if CEACAM6 can be detected in the bile of patients with biliary cancer and can serve as a diagnostic biomarker for cholangiocarcinoma.

Summary Background Data

Distinguishing bile duct carcinoma from other diagnoses is often difficult using endoscopic or percutaneous techniques. The cell surface protein CEACAM6 is over-expressed in many gastrointestinal cancers and may be selectively elevated in biliary adenocarcinoma.

Methods

Bile from patients with benign biliary disease and cholangiocarcinoma (hilar, intrahepatic and distal) was collected at the time of index operation. The concentration of CEACAM6 was quantified by sandwich enzyme-linked immunosorbent assay (ELISA) and correlated to pathologic diagnosis. Diagnostic capability of CEACAM6 was evaluated by Wilcoxon rank-sum, linear regression, multiple regression, and receiver operating characteristic (ROC) curve analysis.

Results

Bile from 83 patients was analyzed: 42 with benign disease and 41 with cholangiocarcinoma. Patients in the benign cohort were younger, predominantly female, and had lower median biliary CEACAM6 levels than patients in the malignant cohort (7.5 ng/ml vs. 40 ng/ml; p = <.001). ROC curve analysis determined CEACAM6 to be a positive predictor cholangiocarcinoma with a CEACAM6 level >14 ng/ml associated with 87.5% sensitivity, 69.1% specificity, and a likelihood ratio of 2.8 (AUC 0.74). Multiple regression analysis suggested elevated alkaline phosphatase and the presence of biliary endoprostheses may influence CEACAM6 levels.

Conclusion

Biliary CEACAM6 can identify patients with extrahepatic cholangiocarcinoma with a high degree of sensitivity and should be investigated further as a potential screening tool.

Soluble CEACAM8 interacts with CEACAM1 inhibiting TLR2-triggered immune responses

Lower respiratory tract bacterial infections are characterized by neutrophilic inflammation in the airways. The carcinoembryonic antigen-related cell adhesion molecule (CEACAM) 8 is expressed in and released by human granulocytes. Our study demonstrates that human granulocytes release CEACAM8 in response to bacterial DNA in a TLR9-dependent manner. Individuals with a high percentage of bronchial lavage fluid (BALF) granulocytes were more likely to have detectable levels of released CEACAM8 in the BALF than those with a normal granulocyte count. Soluble, recombinant CEACAM8-Fc binds to CEACAM1 expressed on human airway epithelium. Application of CEACAM8-Fc to CEACAM1-positive human pulmonary epithelial cells resulted in reduced TLR2-dependent inflammatory responses. These inhibitory effects were accompanied by tyrosine phosphorylation of the immunoreceptor tyrosine-based inhibitory motif (ITIM) of CEACAM1 and by recruitment of the phosphatase SHP-1, which could negatively regulate Toll-like receptor 2-dependent activation of the phosphatidylinositol 3-OH kinase-Akt kinase pathway. Our results suggest a new mechanism by which granulocytes reduce pro-inflammatory immune responses in human airways via secretion of CEACAM8 in neutrophil-driven bacterial infections.

Generation of inducible immortalized dendritic cells with proper immune function in vitro and in vivo

Dendritic cells are the professional antigen presenting cells of innate immunity and key players in maintaining the balance of immune responses. Studies with dendritic cells are mainly limited by their low numbers in vivo and their difficult maintenance in vitro. We differentiated bone marrow cells from transgenic mice expressing an inducible SV40 large T-antigen into dendritic cells. When immortalized by dexamethasone and doxycycline, these cells were stable in long-term culture. In the absence of dexamethasone and doxycycline (de-induction), dendritic cells displayed properties of primary cells, characterized by expression of classical dendritic cell surface markers CD11c, CD11b, MHCII, CD40 and CD86. Furthermore, de-induced lipopolysaccharide activated dendritic cells secreted IL-1β, IL-6, TNFα and IL-12. De-induced, Ovalbumin-loaded dendritic cells polarize CD4(+) T cells into Th1, Th17 and Th2 cells, indicating their correct antigen presenting property. Consistent with intratracheal application of Ovalbumin-loaded primary dendritic cells into mice, the application of de-induced dendritic cells resulted in recruitment of lymphocytes to the lungs. In summary, we successfully expanded dendritic cells using conditional immortalization. The generated dendritic cells demonstrate the characteristic immunophenotype of primary dendritic cells and will facilitate further studies on immunomodulatory properties of dendritic cells.

Two new synthetic peptides from the N-domain of CEACAM1 (CD66a) stimulate neutrophil adhesion to endothelial cells

Four members of the carcinoembryonic antigen family, CEACAMs 1, 3, 6, and 8, are expressed on human neutrophils and can trigger an activation signal that increases neutrophil adhesion to human umbilical vein endothelial cell (HUVEC) monolayers. To identify active sites on CEACAM1, we previously performed molecular modeling using IgG and CD4 as models, and 28 peptides of 14 amino acids in length were synthesized that were predicted to be present at loops and turns between β-sheets. Three peptides, each from the N-terminal domain, increased neutrophil adhesion to HUVEC monolayers and upregulated cell-surface CD11b/CD18 expression on neutrophils. In our earlier study, one N-domain peptide (CD66a-7) was not successfully synthesized, and another N-domain peptide (CD66a-6) was not soluble in the assay system. In the present study, we have now successfully synthesized CD66a-7, and a new peptide (CD66a-6L), that is a modification of the peptide that was insoluble in the earlier study. Both of these new peptides increased neutrophil adhesion to HUVEC monolayers. Importantly, the amino acid sequence of CD66a-7 is identical to the homologous peptides from CEACAMs 3, 5, and 6, but differs from the homologous peptide of CEACAM8, which was not active in this system. CD66a-6L is identical to the homologous peptide from CEACAM6. The data suggest that peptide motifs from at least five regions of the N-terminal domain of CEACAM1 are involved in the interaction of CEACAM1 with other ligands and can initiate signal transduction in neutrophils. Some of these active peptides are identical to homologous regions of other CEACAMs.

Interdependency of CEACAM-1, -3, -6, and -8 induced human neutrophil adhesion to endothelial cells

Members of the carcinoembryonic antigen family (CEACAMs) are widely expressed, and, depending on the tissue, capable of regulating diverse functions including tumor promotion, tumor suppression, angiogenesis, and neutrophil activation. Four members of this family, CEACAM1, CEACAM8, CEACAM6, and CEACAM3 (recognized by CD66a, CD66b, CD66c, and CD66d mAbs, respectively), are expressed on human neutrophils. CD66a, CD66b, CD66c, and CD66d antibodies each increase neutrophil adhesion to human umbilical vein endothelial cell monolayers. This increase in neutrophil adhesion caused by CD66 antibodies is blocked by CD18 mAbs and is associated with upregulation of CD11/CD18 on the neutrophil surface. To examine potential interactions of CEACAMs in neutrophil signaling, the effects on neutrophil adhesion to human umbilical vein endothelial cells of a set of CD66 mAbs was tested following desensitization to stimulation by various combinations of these mAbs. Addition of a CD66 mAb in the absence of calcium results in desensitization of neutrophils to stimulation by that CD66 mAb. The current data show that desensitization of neutrophils to any two CEACAMs results in selective desensitization to those two CEACAMs, while the cells remain responsive to the other two neutrophil CEACAMs. In addition, cells desensitized to CEACAM-3, -6, and -8 were still responsive to stimulation of CEACAM1 by CD66a mAbs. In contrast, desensitization of cells to CEACAM1 and any two of the other CEACAMs left the cells unresponsive to all CD66 mAbs. Cells desensitized to any combination of CEACAMs remained responsive to the unrelated control protein CD63. Thus, while there is significant independence of the four neutrophil CEACAMs in signaling, CEACAM1 appears to play a unique role among the neutrophil CEACAMs. A model in which CEACAMs dimerize to form signaling complexes could accommodate the observations. Similar interactions may occur in other cells expressing CEACAMs.

Les contrôles nécessaires en immunohistochimie : de la recherche au diagnostic

The specificity of an immunohistochemical reaction is guaranteed by two sets of controls. Positive controls verify the specificity of the primary antibody and demonstrate that it binds only to the protein which was used as an immunogen. Negative controls ensure that the labelling technique is specific and that the primary antibody is responsible for generation of the immunostaining. In fact, the production of a labelling may also be related to cross reactivity or to non-specific physical or chemical interactions. This paper reviews the characteristics of various epitopes and antibodies, describes different strategies which prove the specificity of the immunohistochemical reaction in research or diagnostic pathology and point towards the essential information which should be reported in a paper.

Systemic activation and vascular infiltration of neutrophils with term labor

OBJECTIVE

The purpose of the current study was to determine if neutrophils infiltrate maternal systemic vascular tissue at the time of term labor.

METHODS

Subcutaneous fat biopsies were obtained at cesarean delivery or abdominal surgery from laboring women (n = 5), non-laboring women (n = 5), and normal non-pregnant women (n = 5). Immunohistochemical staining was performed for CD66b, a neutrophil antigen, and intercellular adhesion molecule-1 (ICAM-1; CD54), an endothelial cell adhesion molecule for neutrophils. Vessels (10 to 200 microm) were analyzed for intensity of staining and percentage of vessels with staining.

RESULTS

CD66b staining intensity was significantly greater for laboring women at term than for non-laboring women at term or for normal non-pregnant women (1.3 +/- 0.3 versus 0.2 +/- 0.1 versus 0.2 +/- 0.1, respectively, P < .01). Laboring women had significantly more vessels with staining for CD66b (79 +/- 4 versus 24 +/- 8 versus 19 +/- 6%, P < .001), more vessels with neutrophils adhered and flattened to endothelium (67 +/- 3 versus 16 +/- 7 versus 12 +/- 4%, P < .001), more vessels with neutrophils in the intima (30 +/- 6 versus 5 +/- 2 versus 2 +/- 1%, P < .05), and a greater number of neutrophils per vessel (5.4 +/- 1.1 versus 1.7 +/- 0.5 versus 1.2 +/- 0.3, P < .01) as compared to non-laboring or normal non-pregnant women. ICAM-1 staining was present in the endothelium of all groups, with no difference in staining intensity or percent of vessels stained. Between 86% to 96% of vessels stained for ICAM-1. Laboring patients had numerous leukocytes stained for ICAM-1 in their vessels.

CONCLUSION

This study demonstrates that neutrophils infiltrate maternal systemic vascular tissue at the time of term labor. Neutrophils were flattened and adhered to endothelium and infiltrated into the intimal space.

CEACAM1: contact-dependent control of immunity

The carcinoembryonic-antigen-related cell-adhesion molecule (CEACAM) family of proteins has been implicated in various intercellular-adhesion and intracellular-signalling-mediated effects that govern the growth and differentiation of normal and cancerous cells. Recent studies show that there is an important role for members of the CEACAM family in modulating the immune responses associated with infection, inflammation and cancer. In this Review, we consider the evidence for CEACAM involvement in immunity, with a particular emphasis on CEACAM1, which functions as a regulatory co-receptor for both lymphoid and myeloid cell types.

CEACAM1 (CD66a) mediates delay of spontaneous and Fas ligand-induced apoptosis in granulocytes

Granulocytes form the first and fastest line of defense against pathogenic infections. Their survival is limited by apoptosis, a process that is critical for the resolution of inflammation. Pro-apoptotic and pro-inflammatory cytokines, as well as several receptors, can alter the lifespan of granulocytes. Here we report that the carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1, CD66a) is involved in the regulation of granulocyte survival. Until now CEACAM1 is described to control cell proliferation, cell migration, tumor growth, angiogenesis and diverse leukocyte functions. However, very little is known about its role in granulocytes. We found that CEACAM1 expression in resting rat granulocytes is significantly higher than in other leukocyte subtypes. Stimulation led to a strongly increased CEACAM1 cell surface expression and to release of soluble CEACAM1. DNA fragmentation assays and annexin V staining revealed that binding of CEACAM1-specific antibodies, Fab fragments and soluble CEACAM1-Fc constructs to cell surface-expressed CEACAM1 causes a delay of spontaneous and Fas ligand (CD95L)-induced apoptosis. Tyrosine phosphorylation of CEACAM1-L, its association with SHP-1, the activation of Erk1/2 and caspase-3 appeared to be crucial for the CEACAM1-mediated anti-apoptotic effect. These findings provide evidence that CEACAM1 influences the resolution of inflammation by prolonging the survival of rat granulocytes.

An enzyme-linked immunosorbent assay for human carcinoembryonic antigen-related cell adhesion molecule 8, a biological marker of granulocyte activities in vivo

Carcinoembryonic antigen-related cell adhesion molecule 8 (CEACAM8), also known as CD66b, NCA-95 and CD67, is a highly glycosylated protein expressed only in neutrophils and eosinophils in humans. The precise function of CEACAM8 remains unclear. As a member of the family of carcinoembryonic antigen (CEA), it may play a role in the interaction between granulocytes or between granulocytes and epithelial cells. We describe here an accurate, specific and reproducible enzyme-linked immunosorbent assay (ELISA) using purified native CEACAM8 as standard for the measurement of CEACAM8 with a detection range of 1-64 microg/l. We also present data on the levels of CEACAM8 in the blood of healthy individuals and patients undergoing surgery, as well as in patients with acute infections. The highly elevated levels of CEACAM8 in the blood of these patients, which are significantly correlated with the surface expression of CEACAM8 on neutrophils and the number of circulating neutrophils, suggest that CEACAM8 could serve as a biological marker for granulocyte activities in vivo.

Purification and characterization of a 95-kDa protein--carcinoembryonic antigen-related cell adhesion molecule 8--from normal human granulocytes

A 95-kDa protein was purified to homogeneity from granule extracts of normal human granulocytes. The column procedure consisted of Sephadex G-75, Mono-S cation exchange and Superdex HR 75 chromatography. The purified protein showed only one broad band at a molecular weight of 95 kDa when analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE). It reacted with polyclonal antibodies against carcinoembryonic antigen (CEA) and a specific monoclonal antibody against CD66b, but did not react with monoclonal antibodies against CD66acde and CD66c when analyzed by immunoblotting. The molecular weight of the protein shifted from 95 to 40 kDa on SDS-PAGE after deglycosylation. Tryptic peptide analysis by MALDI-Tof identified four peptides with spectra of m/z matching the expected tryptic peptides from a CGM6 gene product. Furthermore, the nanoelectrospray mass spectrometry (MS/MS) analysis of the two selected tryptic peptides of the protein revealed two amino acid sequences corresponding to residues 79-98 and 199-207 of the CGM6 gene product. Based on this, and also on the immunochemical data, it is concluded that the purified 95 kDa is identical to carcinoembryonic antigen-related cell adhesion molecule 8 (CEACAM8) (nonspecific cross-reacting antigen (NCA)-95, CD67 and CD66b) and is a product of the CGM6 (W272) gene. We present, for the first time, a method for the purification of CEACAM8 from normal human granulocytes, which should be useful for further studies on its structure and functions. We also confirmed at the protein level that CEACAM8 is a product of the CGM6 (NCA-W272) gene.

Mice Transgenic for the Human CGM6 Gene Express Its Product, the Granulocyte Marker CD66b, Exclusively in Granulocytes

The nonspecific cross-reacting antigen-95 (NCA-95/CD66b), is a member of the human carcinoembryonic antigen (CEA) family encoded by the CGM6 gene that is exclusively expressed in neutrophils and eosinophils. No murine counterpart is known to exist. We have analyzed a cosmid containing the complete CGM6 gene. The coding sequence is contained within six exons spanning a 16.5 kb region. The main transcriptional start site was mapped to a tight cluster between nucleotides -95 and -101 relative to the translational start site. As with other members of the CEA gene family, no typical TATA or CAAT-box sequences were found in the CGM6 gene. Transgenic mice were established with the cosmid insert. CD66b expression is first seen in the fetal liver on day 12.5 of mouse embryonic development, and it first appears in the bone marrow at day 17.5. Northern blot analysis showed that CD66b transcripts are confined to the bone marrow of adult mice, whereas immunohistochemistry also showed CD66b-positive granulocytes in the spleen, thymus, and lungs. FACScan analyses of bone marrow and spleen cells showed CD66b expression to be exclusive to granulocytes. Thus, all the elements necessary for regulating granulocyte-specific expression are present within this cosmid clone. These mice could provide a model for transplantation and for inflammation studies using CD66b as a granulocyte-specific marker.

Mice Transgenic for the Human CGM6 Gene Express Its Product, the Granulocyte Marker CD66b, Exclusively in Granulocytes

The nonspecific cross-reacting antigen-95 (NCA-95/CD66b), is a member of the human carcinoembryonic antigen (CEA) family encoded by the CGM6 gene that is exclusively expressed in neutrophils and eosinophils. No murine counterpart is known to exist. We have analyzed a cosmid containing the complete CGM6 gene. The coding sequence is contained within six exons spanning a 16.5 kb region. The main transcriptional start site was mapped to a tight cluster between nucleotides -95 and -101 relative to the translational start site. As with other members of the CEA gene family, no typical TATA or CAAT-box sequences were found in the CGM6 gene. Transgenic mice were established with the cosmid insert. CD66b expression is first seen in the fetal liver on day 12.5 of mouse embryonic development, and it first appears in the bone marrow at day 17.5. Northern blot analysis showed that CD66b transcripts are confined to the bone marrow of adult mice, whereas immunohistochemistry also showed CD66b-positive granulocytes in the spleen, thymus, and lungs. FACScan analyses of bone marrow and spleen cells showed CD66b expression to be exclusive to granulocytes. Thus, all the elements necessary for regulating granulocyte-specific expression are present within this cosmid clone. These mice could provide a model for transplantation and for inflammation studies using CD66b as a granulocyte-specific marker.

A monoclonal antibody modulates neutrophil adherence while enhancing cell motility

A monoclonal antibody (MoAb) to human neutrophils, designated 3H9, was established by screening for the inhibition of neutrophil adherence to plastic plates containing a medium supplemented with fetal calf serum (FCS medium). The antigen recognized by 3H9 was shown to be present on human leukocytes and found at the highest levels on granulocytes. On Western blotting, 3H9 reacted with a molecule having a molecular weight of 80 kDa. When this MoAb was added at the same time as a neutrophil stimulant (fMLP), the inhibition of neutrophil adherence to plastic plates in the presence of FCS medium was observed after 60 min incubation. Furthermore, this MoAb enhanced not only fMLP-induced chemotaxis but random migration of neutrophils as well. The mechanisms of these phenomena are discussed.

Role of nonspecific cross-reacting antigen, a CD66 cluster antigen, in activation of human granulocytes

Nonspecific cross-reacting antigen (NCA) is the name of a family of highly glycosylated bacterial-binding receptors found on human granulocytes and other tissues. These glycoproteins are members of the immunoglobulin supergene family and are related structurally to carcinoembryonic antigen. In this study, we demonstrate that ligation of granulocyte NCA results in the activation of the cells, as measured by degranulation and the flux of intracellular calcium. These studies further the proposition that NCA has a function in the immune response of granulocytes against bacterial infections.

Immunochemical analysis of carcinoembryonic antigen (CEA)-related antigens differentially localized in intracellular granules of human neutrophils

Subcellular localization and antigenic properties of eight carcinoembryonic antigen (CEA)-related proteins (nonspecific cross-reacting antigens, NCAs) in neutrophils, including CD66 antigens, were examined with a panel of CD66 monoclonal antibodies (MAbs), whose specificities were characterized with CHO cells expressing CEA gene family recombinant proteins. Intracellular granules of neutrophils were isolated by cell lysis followed by centrifugation on a sucrose gradient. SDS-PAGE analysis of immunoprecipitates from the granules revealed that NCA-95 (CD66c, NCA-50/90) exists predominantly in the azurophil granule-enriched fraction. NCA-90 was identified in the same fraction and was suggested to be a molecule closely-related to NCA-95. NCA-26 was identified in the specific granule fraction together with NCA-160 (CD66a, BGP), and was likely a splicing variant of NCA-160. NCA-100 (CD66b, CGM6) was also identified in this fraction. NCA-80, -58 and -30, which are detectable in culture medium of neutrophils with polyclonal anti-NCA-50/90, were not recognized by any of the CD66 MAbs tested. These findings indicate that NCA-160, -100, -95, -90 and -26 are the products of the CEA gene family and stored separately in azurophil and specific granules. It remains to be clarified whether or not the other three secretory antigens, NCA-80, -58 and -30, are still unknown members of the CEA family.

Non-proteolytic release of carcinoembryonic antigen from normal human colonic epithelial cells cultured in collagen gel

Recent studies have shown that, even with a minimal content of carcinoembryonic antigen (CEA), normal human colonic epithelial cells express substantial amounts of CEA mRNA and colonic mucosal fragments cultured in vitro produce CEA quite actively, indicating that CEA should no longer be considered to be of an oncofetal nature. To understand the basis of the usefulness of CEA as a tumor marker, we analyzed the release of CEA, a glycosyl-phosphatidylinositol (GPI)-anchored protein, from colonic epithelial cells, by culturing isolated colonic crypts in collagen gel. The crypts appeared to preserve their morphological and biochemical integrity in the gel for at least 16 hr, and released CEA spontaneously. Three forms of CEA--spontaneously released CEA, CEA liberated with phosphatidylinositol-specific phospholipase C (PI-PLC) and CEA in cell lysates--were indistinguishable on SDS-PAGE. This is in contrast to recombinant CEA spontaneously released from CHO transfectants, which showed a smaller molecular mass than that of PI-PLC-cleaved recombinant CEA. By phase separation using Triton X-114, CEA in the cell lysates of crypts was separated mostly into the detergent phase, while the spontaneously released and the PI-PLC-cleaved CEA were separated into the aqueous phase. When the cells were metabolically labeled with the precursors of the GPI-anchor, 3H-ethanolamine but not 3H-palmitic acid was found in the spontaneously released CEA. These findings suggest that, in contrast to the proteolysis-like release of the recombinant CEA from CHO cells, CEA in normal colonic epithelial cells is released by a non-proteolytic cleavage, which probably occurs through the action of some endogenous phospholipase.

Characterization of monoclonal antibodies specific for monocytes, macrophages and granulocytes from porcine peripheral blood and mucosal tissues

A panel of four monoclonal antibodies produced in our laboratory, MIL1, MIL2, MIL3, MIL4, and the type-specific monocyte/granulocyte marker 74-22-15 were used to isolate and to discriminate between monocytes, macrophages and granulocytes derived from porcine peripheral blood, lung and gut lamina propria. Two-colour flow cytometry and cell sorting showed that while no monoclonal antibody was specific for just a single cell population, each cell type had a unique and characteristic combination of surface antigens. These differences could be used to identify and purify monocytes, macrophages, neutrophils, eosinophils and basophils from the three different sites. The study also demonstrated similarities and differences within cell types from the same site and from different sites: polymorphonuclear neutrophils (PMN) from peripheral blood were subdivided into two subpopulations by the presence or absence of the surface antigen recognized by MIL4, while PMN from alveolar lavage did not express this antigen. Peripheral blood eosinophils were also divided into subpopulations by the presence or absence of the same surface antigen. Lamina propria eosinophils strongly expressed the MIL4 marker and differed morphologically from blood eosinophils. Peripheral blood basophils and lamina propria mast cells were morphologically similar and expressed similar antigens. Monocytes and alveolar macrophages also expressed the same surface antigens.

Characterization of a species of non-specific cross-reacting antigen (NCA) expressed by human monocytic cell lines: structure and expression during cell differentiation

It has been documented that human monocytes/macrophages are reactive with antibodies directed to carcinoembryonic antigen (CEA) and non-specific cross-reacting antigens (NCAs), a group of glycoproteins antigenically cross-reactive with CEA, yet the molecules responsible for this antigenic activity have not been fully clarified. In the present study, among 7 myelomonocytic cell lines tested, 2 monoblastoid lines, U-937 and THP-1, were found to express NCA-50/90, a glycosylphosphatidylinositol-anchored cell-adhesion molecule chiefly expressed on granulocytes. The 2 cell lines showed a reaction pattern with 5 distinct anti-CEA and anti-NCA monoclonal antibodies, similar to that of CHO transfectants expressing recombinant NCA-50/90. Immunoprecipitation and SDS-PAGE analyses identified glycoproteins of about 95 and 55 kDa in U-937 and THP-1 cells, respectively. Deglycosylation of the 2 antigens with N-glycanase gave the same apparent molecular mass of about 45,000, which was also the same as that of the deglycosylated form of the recombinant NCA-50/90. Upon Northern-blot analysis, only one band of approximately 2.5 kb was detected in both cell lines with a cDNA probe for NCA-50/90, which has a broad specificity to the CEA gene family members. cDNA cloning demonstrated that the 2.5-kb clones encode the peptide of NCA-50/90. The expression of NCA-50/90 by U-937 and THP-1 was down-regulated at both the protein and mRNA levels during cell differentiation from monoblastoid to monocyte/macrophage-like cells induced by stimulation with phorbol 12-myristate 13-acetate. Our observations suggest that NCA-50/90 is a differentiation antigen of cells of the monocyte/macrophage lineage as well as of the granulocyte lineage.