Epithelial Mucin Research Articles

74: Targeting MUC1 as a Marker for Myeloid Leukemia Stem Cells by DC/AML Fusions

The epithelial mucin antigen (MUC1) is aberrantly expressed in many epithelial tumors and hematologic malignancies and has served as a target for cellular immunotherapy. In this study, we examined MUC1 as a marker for myeloid leukemia cells and their progenitors. Myeloid leukemia cells were isolated from bone marrow aspirates or peripheral blood. MUC1 was not expressed on unselected leukemia cells (mean expression 3%, n = 12). A subset of samples underwent CD34 selection by magnetic bead separation.

Small Airway Mucous Metaplasia and Inflammation in Chronic Obstructive Pulmonary Disease

Mucous metaplasia is an important determinant of small airway obstruction in COPD. Its relationship to small airway inflammation is poorly defined. We analyzed 4 to 6 small airways in 19 COPD patients, GOLD stages 0–4, from lobectomy or lung volume reduction surgery tissue samples. To identify intracellular mucin, periodic acid fluorescent Schiff's (PAFS) stained slides were imaged by fluorescence microscopy. PAFS+ staining area, basement membrane length (LBM), epithelial height and area were measured. Mucin was expressed as a percentage of epithelial area. Mucin volume density (MVD) was calculated as PAFS+ area divided by the product of LBM and 4/π. Airways were Giemsa stained for eosinophils and immunostained with antibodies against CD3, CD4, CD8, CD68, and neutrophil elastase (NE), and the number of positively stained cells/mm2 was quantified in the airway wall. Mucin percent correlated with CD3+ cell density (r = 0.553, P < 0.0001), and MVD correlated with CD3+ (r = 0.570, P < 0.0001) and CD8+ cell density (r = 0.279, P = 0.016). There were weak negative correlations between mucin percent as well as MVD and CD68+ cell density (r = −0.270, P = 0.02 and r = −0.245, P = 0.036). There was no relationship between epithelial mucin content and CD4+, NE+, or eosinophil cell density. CD3+ and CD8+ lymphocytic inflammation is related to small airway mucous metaplasia in COPD and may play a causative role in its development.

The detection of micrometastases in the peripheral blood of patients with breast cancer for hSBEM mRNA and CD44V6 mRNA

Successful treatment of breast cancer greatly depends on the early detection of its metastasis, therefore a sensitive and specific biomarker for detecting dissemination of the cancer cells will help to achieve this goal. This study was to evaluate the prognostic significance of human small breast epithelial mucin (hSBEM) and CD44V6 in breast cancer. The expressions of hSBEM mRNA and CD44V6 mRNA were detected with nested reverse transcription polymerase chain reaction (nested RT-PCR) in 67 samples of breast cancer and adjacent normal breast tissue, 16 samples of breast benign lesions tissue, and 67 specimens of peripheral blood from patients with breast cancer, 16 specimens of benign breast lesions, 20 specimens of healthy volunteers, and 25 (each five cases) other carcinomas tissue samples, including those of gastric carcinoma, colorectal carcinoma, esophageal carcinoma, lung carcinoma, and ovary carcinoma, were analyzed for hSBEM mRNA expression by nested RT-PCR. hSBEM mRNA expression was observed in 62/67 (92.54%) of breast cancer, 14/16 (87.50%) of breast benign lesions and 59/67 (88.05%) of normal breast tissue, with no significant differences between them (P > 0.05). None of the samples from other cancer tissues were positive. In peripheral blood the expression of hSBEM mRNA was detected in 34/67 (50.75%) from patients with breast cancer, with significant increasing (P 0.05) in the patients with breast cancer (82.09%), benign breast lesion (75.00%), or healthy volunteers (70.00%). The expressions of hSBEM mRNA and CD44V6 mRNA had no correlation with the age of the patients, size of primary tumor, histological type and estrogen or progestin receptor status (P > 0.05). hSBEM mRNA, as assessed by nested RT-PCR, shows a mammary-specific and mammary-sensitive expression, and is a sensitive indicator of hematogeneous spread of breast cancer cell, while CD44V6 shows low sensitivity and specificity in detecting dissemination of breast cancer cell in peripheral blood. hSBEM mRNA is a promising molecular biomarker for detecting breast cancer micrometastases.

Chronic Exposure to Beta-Blockers Attenuates Inflammation and Mucin Content in a Murine Asthma Model

Single-dose administration of beta-adrenoceptor agonists produces bronchodilation and inhibits airway hyperresponsiveness (AHR), and is the standard treatment for the acute relief of asthma. However, chronic repetitive administration of beta-adrenoceptor agonists may increase AHR, airway inflammation, and risk of death. Based upon the paradigm shift that occurred with the use of beta-blockers in congestive heart failure, we previously determined that chronic administration of beta-blockers decreased AHR in a murine model of asthma. To elucidate the mechanisms for the beneficial effects of beta-blockers, we examined the effects of chronic administration of several beta-adrenoceptor ligands in a murine model of allergic asthma. Administration of beta-blockers resulted in a reduction in total cell counts, eosinophils, and the cytokines IL-13, IL-10, IL-5, and TGF-beta1 in bronchoalveolar lavage, and attenuated epithelial mucin content and morphologic changes. The differences in mucin content also occurred if the beta-blockers were administered only during the ovalbumin challenge phase, but administration of beta-blockers for 7 days was not as effective as administration for 28 days. These results indicate that in a murine model of asthma, chronic administration of beta-blockers reduces inflammation and mucous metaplasia, cardinal features of asthma that may contribute to airflow obstruction and AHR. Similar to heart failure, our results provide a second disease model in which beta-blockers producing an acutely detrimental effect may provide a therapeutically beneficial effect with chronic administration.

Mucin immunohistochemistry in the diagnosis and mapping of extramammary Paget's disease.

Extramammary Paget's disease (EMPD) is a rare skin cancer of the genital region in which cancer cells with enlarged nuclei and pale cytoplasm are scattered singly in the affected epidermis. These cancer cells, called Paget cells, contain mucin, which is never found in normal epidermis. The oligosaccharide side chains of Paget cell mucin end with sialic acid. Sialic acid is easily detected by zirconyl haematoxylin or alcian blue. The other sugars in the oligosaccharide chains can be detected by the periodic acid-Shiff reaction. Rarely, the diagnosis of EMPD is complicated by the absence of mucin from the Paget cells. We have examined such an atypical case. The oligosaccharide side chains, including the sialic acids, are absent. In both this case and a typical case, the Paget cells contain epithelial membrane antigen mucin (MUC1) core protein and usually contain gastric surface-type mucin (MUC5AC) core protein, which can be stained by antibodies. Since neither core protein is found in normal epidermis, epithelial membrane antigen core protein may be the most reliable diagnostic marker for extramammary Paget's disease. In both the atypical case and the typical case of Paget's diseas, some cells that look like keratinocytes contain mucin core proteins. These may be incipient Paget cells. We suggest that using th epithelial membrane antigen core protein as a marker for the true extent of extramammary Paget's disease could facilitate complete excision and reduce the rate of recurrence.

Lung Lining Fluid Glutathione Attenuates IL-13–Induced Asthma

GGT(enu1) mice, deficient in gamma-glutamyl transferase and unable to metabolize extracellular glutathione, develop intracellular glutathione deficiency and oxidant stress. We used intratracheal IL-13 to induce airway inflammation and asthma in wild-type (WT) and GGT(enu1) mice to determine the effect of altered glutathione metabolism on bronchial asthma. WT and GGT(enu1) mice developed similar degrees of lung inflammation. In contrast, IL-13 induced airway epithelial cell mucous cell hyperplasia, mucin and mucin-related gene expression, epidermal growth factor receptor mRNA, and epidermal growth factor receptor activation along with airway hyperreactivity in WT mice but not in GGT(enu1) mice. Lung lining fluid (extracellular) glutathione was 10-fold greater in GGT(enu1) than in WT lungs, providing increased buffering of inflammation-associated reactive oxygen species. Pharmacologic inhibition of GGT in WT mice produced similar effects, suggesting that the lung lining fluid glutathione protects against epithelial cell induction of asthma. Inhibiting GGT activity in lung lining fluid may represent a novel therapeutic approach for preventing and treating asthma.

Targeting MUC1 as a Marker for Myeloid Leukemia Stem Cells by DC/AML Fusions.

The epithelial mucin antigen (MUC1) is aberrantly expressed in many epithelial tumors and hematologic malignancies and promotes oncogenesis and tumor progression. MUC1 is recognized by the T cell repertoire and has served as a target for cellular immunotherapy. In the present study, we examined MUC1 as a marker for myeloid leukemia cells and their progenitors and its capacity to serve as a target for leukemia stem cells. Myeloid leukemia cells were isolated from bone marrow aspirates or peripheral blood in patients with high levels of circulating disease. MUC1 was not expressed on unselected leukemia samples (mean expression 3%, n=12). Similarly, low levels of MUC1 expression were seen in leukemic blasts with monocytoid differentiation (mean expression 2.7%, n=5). A subset of leukemia specimens underwent CD34 selection by magnetic bead separation. In contrast to unselected cells, 38% of CD34+ leukemia cells expressed MUC1 (n=5). The leukemia stem cell compartment was isolated by separating CD34+/CD38−/ lineage- fractions by flow cytometric sorting. Leukemia stem cells demonstrated strong expression of MUC-1 by immunohistochemical staining and FACS analysis. Similarly, we examined MUC1 expression on progenitor cells derived from chronic phase chronic myeloid leukemia and following blast transformation. MUC1 was seen in only 4% of CD34+ cells obtained from chronic phase CML samples (n=4) while uniform expression was observed in samples derived from patients with accelerated/blastic phase disease. These data suggest that MUC1 serves as a marker for early leukemia progenitors and is associated with blastic transformation. We assessed the capacity of a cancer vaccine consisting of dendritic cell (DC)/myeloid leukemia fusions to stimulate immune responses that target MUC1 and other antigens expressed by the stem cell compartment. DCs were generated from adherent mononuclear cells that were cultured with GM-CSF and IL-4 and matured with TNFa. DCs were fused with patient derived myeloid leukemia cells using polyethylene glycol as previously described. Fusion cells were quantified by determining the percentage of cells that expressed unique DC and leukemia antigens. DC/AML fusions induced the expansion of MUC1 specific T cells. Stimulation of autologous T cells with DC/AML fusions resulted in a mean 3 fold increase in CD8+ cells binding the MUC-1 tetramer (N=4). DC/AML fusions stimulated anti-tumor immune responses that targeted leukemia stem cells. Fusion stimulated T cells demonstrated increased expression of IFNγ following exposure to lysate generated from unselected leukemia cells (29 fold) and leukemia stem cells (28 fold). In contrast, exposure to renal carcinoma lysate generated only a 5 fold increase in IFNγ. In summary, these findings suggest that leukemic progenitors in AML and accelerated/blast phase CML express MUC-1. DC/tumor fusion vaccines target the MUC-1 protein and the stem cell compartment, and may be a potent immunotherapeutic strategy to eliminate the malignant stem cell clone in AML.

Mucinous breast lesions: diagnostic challenges

Breast lesions with mucin represent a broad spectrum of entities, ranging from benign fibrocystic changes with luminal mucin to mucocele-like lesions (MLL), which can be associated with banal epithelial alterations,...

Biochemical and histochemical effects of perorally applied endotoxin on intestinal mucin glycoproteins of the common carp Cyprinus carpio

Mucins are high molecular weight glycoproteins produced by goblet cells and secreted on mucosal surfaces. We investigated biochemical and histochemical properties of intestinal mucins of virus- and parasite-free common carp Cyprinus carpio in response to a single peroral application of endotoxin (lipopolysaccharide = LPS). Intracellular mucins were quantified histochemically by their carbohydrate content and characterized by specific, lectin-based methods. In addition, secreted epithelial (intracellular) and luminal (extracellular) mucins were isolated and separated by downward gel filtration. Carbohydrate and protein content were determined photometrically. Subsequently, terminal glycosylation was characterized by a lectin-binding assay. A peroral endotoxin application altered intestinal secretion and composition of intestinal mucin glycoproteins in common carp. A statistically significant decrease in mature luminal mucins was demonstrated, linked to a new biosynthesis of intracellular mucin glycoproteins. Simultaneous changes in the glycosylation pattern of isolated mucins were found. The intestinal mucosal system is purported to provide a removal mechanism for bacterial noxes by increasing secretion of mucins inducing a flushing-out effect, in combination with altered glycosylation patterns that change adhesion properties. Consequently, pseudofaeces of fish, which are a common sign of intestinal parasitical infections, may also be interpreted as an elimination mechanism for strong bacterial noxes.

Complement C3a Regulates Muc5ac Expression by Airway Clara Cells Independently of Th2 Responses

The factors that control the secretion of epithelial mucins are essential to understanding obstructive airway diseases such as asthma. Although the complement anaphylatoxin C3a and its receptor have been shown to promote many features of allergic lung inflammation, the contribution to mucin expression has not been elucidated. To determine if the C3a receptor with its ligand regulates airway epithelial mucin production. Mice deficient in the C3a receptor were examined in a model of allergic airway disease for the presence of goblet cells and the gel-forming secreted mucin Muc5ac. Lungs from antigen-challenged C3a receptor-deficient mice revealed a dramatic decrease in goblet cells and Muc5ac compared with challenged wild-type control animals. These differences were dependent on C3a binding to its receptor since intranasal challenge with C3a induced the formation of goblet cells only in wild-type but not C3a receptor-deficient mice. Increased numbers of goblet cells were also found in C3a-stimulated RAG-1-deficient mice demonstrating a mechanism independent of T lymphocytes and Th2 cytokines, mediators which have been shown to regulate mucin expression. A direct physiological role for C3a in these models was further demonstrated in cultures of airway epithelial Clara cells, which not only express the C3a receptor but also produce Muc5ac in response to C3a. These studies identify a novel C3a receptor-dependent mechanism in the development of airway epithelial goblet cells and regulation of Muc5ac production and implicate C3a as a mediator of airway obstruction in asthma.

PANVAC™-VF: poxviral-based vaccine therapy targeting CEA and MUC1 in carcinoma

PANVAC™ is a cancer vaccine therapy delivered through two viral vectors – recombinant vaccinia and recombinant fowlpox – which are given sequentially. Both vectors contain transgenes for the tumor-associated antigens epithelial mucin 1 and carcinoembryonic antigen, which are altered or overexpressed in most carcinomas. The vectors also contain transgenes for three human T cell costimulatory molecules required to enhance immune response: B7.1, intracellular adhesion molecule-1 and leukocyte function-associated antigen-3. PANVAC is injected subcutaneously and processed by the body’s antigen-presenting cells. Preclinical studies have demonstrated the efficacy of PANVAC in inducing both carcinoembryonic antigen- and mucin 1-specific cytotoxic T lymphocyte responses in vitro and in murine models. Other strategies that enhance the immune response include the use of granulocyte-macrophage colony-stimulating factor and a prime–boost administration sequence. Clinical trials have demonstrated PANVAC’s safety and its ability to induce antigen-specific T cell responses. Early clinical trials are evaluating PANVAC alone and in combination with conventional chemotherapy and/or radiation. Studies to date hold promise for the use of PANVAC as a means to stimulate the immune system against malignancies and to provide clinical benefit.

Microparticle-associated tissue factor activity: a link between cancer and thrombosis?

Cancer, in particular mucinous adenocarcinoma, is associated with venous thromboembolism (VTE). Tissue factor (TF), initiator of coagulation, plays a central role in the paradigm that clotting and tumor growth form a vicious circle, in which hypercoagulability facilitates the aggressive biology of cancer and vice versa. Expression of TF in tumors is associated with poor differentiation and poor prognosis. We investigated the association between clinically manifest VTE and procoagulant properties of circulating microparticles (MP) isolated from blood of unselected pancreatic and breast adenocarcinoma patients' consecutive subjects, who presented with ultrasound or CT-scan confirmed VTE, and healthy subjects. Patients with disseminated breast and pancreatic cancer had significantly increased levels of MP-associated TF activity compared with healthy controls, subjects with idiopathic acute VTE and non-metastatic cancer patients. Patients with both high MP-associated TF-activity and MP-associated epithelial mucin (MUC1) had a lower survival rate at 3-9 months follow-up than those with low TF-activity and no MUC1 expression: the likelihood of survival was 0.42 (95% CI: 0.19- 0.94) for an individual with these two predictor variables present, after adjustment for other factors (age cohort, type of cancer, VTE) in the Cox proportional hazards model. Our results suggest an important role for MP-associated TF and MUC1 in the pathogenesis of thrombosis in disseminated mucinous adenocarcinoma patients. Future studies should reveal the mechanism underlying the observed associations.

A Novel Role for IκB Kinase (IKK) α and IKKβ in ERK-Dependent Up-Regulation of MUC5AC Mucin Transcription by Streptococcus pneumoniae

Epithelial cells represent the first line of host innate defense against invading microbes by elaborating a range of molecules involved in pathogen clearance. In particular, epithelial mucins facilitate the mucociliary clearance by physically trapping inhaled microbes. Up-regulation of mucin production thus represents an important host innate defense response against invading microbes. How mucin is induced in upper respiratory Streptococcus pneumoniae infections is unknown. In this study, we show that pneumolysin is required for up-regulation of MUC5AC mucin via TLR4-dependent activation of ERK in human epithelial cells in vitro and in mice in vivo. Interestingly, a "second wave" of ERK activation appears to be important in mediating MUC5AC induction. Moreover, IkappaB kinase (IKK) alpha and IKKbeta are distinctly involved in MUC5AC induction via an ERK1-dependent, but IkappaBalpha-p65- and p100-p52-independent, mechanism, thereby revealing novel roles for IKKs in mediating up-regulation of MUC5AC mucin by S. pneumoniae.

Mucin glycoarray in gastric and gallbladder epithelia

BackgroundMucins are critical cytoprotective glycoproteins and alterations of epithelial gastric mucins have been described in different pathological conditions. The purpose of the present study was to evaluate the putative usefulness of mucins in understanding the progression of gastric cancer and gallstone formation in a better perspective.MethodsFormalin-fixed paraffin-embedded gastric biopsy specimens and surgically resected gallbladder tissue samples were sectioned. Alcian Blue (AB) staining was performed to identify sialomucins (staining blue at pH 2.5) and sulfomucins (staining brown at pH 1.0) and then Periodic acid-Schiff's (PAS) staining to visualize the neutral mucins (staining magenta).ResultsIn normal gastric and gallbladder mucosae, we found that neutral mucins were predominant, whereas in intestinal metaplasia, gastric carcinoma and stone-containing gallbladder, a significant increase of acidic mucins was found.ConclusionWe suggest that the sulfomucins have a greater role in gallstone formation than the neutral mucins and also that the sialomucins and sulfomucins play an important role in cancer progression and metastasis. Our results challenge the glycobiologists to delve deeper in elucidating the role of mucins in gastric malignancy and in gallstone formation.

上唇に発生した粘液腺癌の１例

Mucinous adenocarcinoma is a rare malignant neoplasm characterized by a large amount of extracellular epithelial mucin. In the present report, an extremely rare case of a mucinous adenocarcinoma in a minor salivary gland of the upper lip is described, along with a brief discussion. A 82-year-old woman was referred to our department because of a swelling on the left side of the upper lip on May 20, 2004. She noticed the swelling in September 2003. Physical examination revealed a painless nodule, measuringl4×12mm, on the mucosal side of the lip. The nodule felt elastic, firm, and movable. The skin was intact, without tumor invasion. There was no lymphadenopathy palpable in cervical region. Ultrasonography revealed a homogenous hypoechoic tumor with an illdefined margin. On the basis of these findings, a clinical diagnosis of a tumor in the upper lip was made, and excisional biopsy was performed on June 3, 2004. Histopathological examination showed a malignant neoplasm with characteristics indicating mucin production. A metastatic tumor was thus suspected. Therefore, the patient was examined by taking a detailed history and performing radiography and scintigraphy. However, no malignancy was detected in any other organs. Because subsequent histopathological examination revealed signs of residual tumor cells at the resection margin, additional excision of the tumor and skin was planned under general anesthesia. The postoperative course was uneventful. Histopathologically, the tumor was composed of glandular neoplastic cells that produced a large amount of mucin. Nests, cords, sheets, and clusters of neoplastic cells were found floating in mucin pools separated by fibrous connective tissue bands. The final diagnosis was a mucinous adenocarcinoma of the upper lip.

The C-type lectin MGL expressed by dendritic cells detects glycan changes on MUC1 in colon carcinoma.

The epithelial mucin MUC1 is a high molecular weight membrane glycoprotein frequently overexpressed and aberrantly glycosylated in adenocarcinoma. Mucins normally contain high amounts of O-linked carbohydrate structures that may influence immune reactions to this antigen. During malignant transformation, certain glyco-epitopes of MUC1, such as Tn-antigen, TF-antigen and their sialylated forms become exposed. The role of these glycan structures in tumor biology is unknown, but their presence is known to correlate with poor prognosis in several adenocarcinomas. We analyzed the potency of MUC1 containing Tn-antigens (MUC1-Tn) to target C-type lectins that function as carbohydrate recognition and uptake molecules on dendritic cells (DC). We identified the macrophage galactose type C-type lectin (MGL), expressed by both DC and macrophages, as the receptor for recognition and binding of MUC1-Tn. To validate the occurrence of MGL-MUC1 interactions in situ, we studied the binding of MGL to MUC1 in primary colon carcinoma tissue. Isolation of MUC1 out of colon carcinoma tissue showed strong binding activity to MGL. Interestingly, MGL binding to MUC1 was highly correlated to binding by the lectin Helix pomatia agglutinin (HPA), which is associated with poor prognosis in colorectal cancer. The detection of MGL positive cells in situ at the tumor site together with the modified glycosylation status of MUC1 to target MGL on DC suggests that MGL positive antigen presenting cells may play a role in tumor progression.

A deficient TLR2 signaling promotes airway mucin production inMycoplasma pneumoniae-infected allergic mice

The original hygiene hypothesis suggests that early childhood respiratory infections preceding allergen exposure may decrease the prevalence of allergic diseases. We have recently demonstrated that Mycoplasma pneumoniae infection preceding allergen exposure reduced allergic responses in mice. However, the molecular mechanisms underlying the protective role of M. pneumoniae in allergic responses, particularly airway mucin production, remain unclear. Wild-type and Toll-like receptor 2 (TLR2)-deficient mice with a respiratory M. pneumoniae infection preceding allergen (ovalbumin) challenge were utilized to determine the regulatory role of TLR2-IFN-gamma signaling pathway in airway mucin expression. Furthermore, air-liquid interface cultures of mouse primary tracheal epithelial cells were performed to examine the effects of IFN-gamma on mucin expression. In wild-type mice, M. pneumoniae infection preceding allergen challenge significantly reduced airway mucins but increased IFN-gamma. In sharp contrast, in TLR2-deficient mice, M. pneumoniae preceding allergen challenge resulted in increased mucin protein without a noticeable change of IFN-gamma. In cultured mouse primary tracheal epithelial cells, IFN-gamma was shown to directly inhibit mucin expression in a dose-dependent manner. Our study demonstrates for the first time that a respiratory M. pneumoniae infection preceding allergen challenge reduces airway epithelial mucin expression in part through TLR2-IFN-gamma signaling pathway. A bacterial infection in asthmatic subjects with weakened TLR2-IFN-gamma signaling may result in an exaggerated airway mucin production.

Quantitative morphology using bronchial biopsies: FIGURE 1.

Bronchoscopy with bronchial biopsies allows sampling of airway tissue in prospective clinical studies and is increasingly applied for the study of airway inflammation and remodelling.It is important to recognise that there are limitations inherent to the use of bronchial biopsies, including the inability to randomly sample the airway and susceptibility to the “reference trap”. Nonetheless, certain stereological principles can be applied to the analysis of these specimens, which may improve the validity of the results obtained. These principles relate to choice of reference space, adequacy of sampling and treatment of tissue orientation in the estimation of thickness and surface area.With attention to these principles, the present authors have developed protocols for the assessment of multiple measures of airway remodelling in bronchial biopsies, including airway epithelial mucin content, epithelial goblet cell size, reticular basement membrane thickness and smooth muscle morphological outcomes. They have also developed protocols for the enumeration of inflammatory cells important in the study of asthma and chronic obstructive pulmonary disease, including eosinophils and neutrophils.In the present article, relevant stereological principles and the details of these specific protocols will be reviewed.

Detection of SBEM-mRNA in peripheral blood of patients with breast cancer and its clinical significance

Objective The aim of the present study is to explore the expression of a specific marker of breast cancer, small breast epithelial mucin (SBEM) mRNA, in peripheral blood and to investigate its significance.

Alterations of the ocular surface epithelial mucins 1, 2, 4 and the tear functions in patients with atopic keratoconjunctivitis

An increased understanding of the ocular surface alterations at the cellular level in the conjunctiva and the cornea, may help explain the pathogenesis and the subsequent clinical appearance of atopic ocular allergies, which may be potentially blinding. To investigate MUC 1, 2 and 4 alterations, tear function and the ocular surface disorder in patients with atopic keratoconjunctivitis. Twenty-eight eyes of 14 atopic keratoconjunctivitis patients as well as 22 eyes of 11 age-and sex-matched normal subjects were studied. The subjects underwent corneal sensitivity measurements, Schirmer's test, tear film break-up time (BUT), fluorescein and Rose Bengal staining of the ocular surface, conjunctival impression cytology and brush cytology. Impression cytology samples underwent periodic acid-Schiff and immunohistochemical staining with MUC 1, 2 and 4 antibodies. Brush cytology specimens underwent evaluation for inflammatory cell numbers and quantitative real-time-PCR for MUC 1, 2 and 4 mRNA expression. Patient eyes with fluorescein and Rose Bengal scores greater than four points were regarded to have significant epithelial disease in this study. The mean corneal sensitivity and BUT values were significantly lower in atopic patients with significant epithelial disease, compared with patients with insignificant epithelial disease and controls (P < 0.01). Brush cytology specimens from patients with significant epithelial disease revealed significantly higher numbers of inflammatory cells (P < 0.01). Specimens from patient eyes showed positive staining for MUC 1, 2 and 4. MUC 1, 2 and 4 mRNA expressions were significantly higher in eyes with significant epithelial disease compared with eyes with insignificant epithelial disease and eyes of control subjects. Ocular surface inflammation, decline in corneal sensitivity, tear film instability, changes in conjunctival epithelial MUC 1, 2 and 4 mRNA expressions were thought to be important in the pathogenesis of atopic ocular surface disease.