Lymphocyte migration into the skin: the role of lymphocyte homing receptor (CD44) and endothelial cell antigen (HECA-452)

CD44a functions as a regulator of p53 signaling, apoptosis and autophagy in the antibacterial immune response

The cell adhesion molecule CD44 has been implicated in diverse biological functions including the pathological responses to infections and inflammatory diseases. The variable forms of CD44 contribute to functional variations, which are not yet defined in teleost. Here, we show that zebrafish CD44a plays a protective role in the host defense against Edwardsiella piscicida infection. Zebrafish CD44a deficiency inhibits cell growth and proliferation, impairs cell growth and death pathways, and regulates the expression levels of many genes involved in p53 signaling, apoptosis and autophagy. In addition, CD44a gene disruption in zebrafish leads to inhibition of apoptosis and induction of autophagy, with the increased susceptibility to E. piscicida infection. Furthermore, we show that zebrafish CD44a variants including CD44a_tv1 and CD44a_tv2 promote the translocation of p53 from the nucleus to the cytoplasm and interact with p53 in the cytoplasm. Mechanistically, zebrafish CD44a_tv1 mediates the beneficial effect for larvae survival infected with E. piscicida is depending on the CASP8-mediated apoptosis. However, the antibacterial effect of zebrafish CD44a_tv2 depends on the cytoplasmic p53-mediated inhibition of autophagy. Collectively, our results identify that different mechanisms regulate CD44a variants-mediated antibacterial responses.

The adhesion molecule CD44 drives host defence in zebrafish by regulating apoptosis and autophagy.

ICAM-1null C57BL/6 Mice Are Not Protected from Experimental Ischemic Stroke

Accumulation of neutrophils in the brain is a hallmark of cerebral ischemia and considered central in exacerbating tissue injury. Intercellular adhesion molecule (ICAM)-1 is upregulated on brain endothelial cells after ischemic stroke and considered pivotal in neutrophil recruitment as ICAM-1-deficient mouse lines were found protected from experimental stroke. Translation of therapeutic inhibition of ICAM-1 into the clinic however failed. This prompted us to investigate stroke pathogenesis in Icam1^tm1Alb C57BL/6 mutants, a true ICAM-1^null mouse line. Performing transient middle cerebral artery occlusion, we found that absence of ICAM-1 did not ameliorate stroke pathology at acute time points after reperfusion. Near-infrared imaging showed comparable accumulation of neutrophils in the ischemic hemispheres of ICAM-1^null and wild type C57BL/6 mice. We also isolated equal numbers of neutrophils from the ischemic brains of ICAM-1^null and wild type C57BL/6 mice. Immunostaining of the brains showed neutrophils to equally accumulate in the leptomeninges and brain parenchymal vessels of ICAM-1^null and wild type C57BL/6 mice. In addition, the lesion size was comparable in ICAM-1^null and wild type mice. Our study demonstrates that absence of ICAM-1 neither inhibits cerebral ischemia-induced accumulation of neutrophils in the brain nor provides protection from ischemic stroke.

Decreased numbers of circulating plasmablasts and differences in IgA1-plasmablast homing to skin in coeliac disease and dermatitis herpetiformis

The two clinical phenotypes of gluten enteropathy, coeliac disease (CD) and dermatitis herpetiformis (DH), were characterized for numbers and homing profiles of circulating final effector B cells, plasmablasts, identified as immunoglobulin (Ig)-secreting cells (ISC). In CD, the numbers of ISC were approximately 50% lower than in DH or controls. ISC expressed peripheral lymph node homing receptor (HR), L-selectin, less frequently in CD (54%) and DH (52%) patients than in controls (70%). The expression of gut mucosal HR, alpha(4)beta(7), was less frequent in CD (42%) than in DH (65%) or controls (60%). In DH, but not in CD or controls, a higher proportion of IgA1-ISC (40%) than IgA2-ISC (25%) expressed the skin HR, cutaneous lymphocyte-associated antigen. In gluten enteropathy circulating plasmablasts are more mature, but decreased in number, and have distorted homing profiles. Differential IgA1-plasmablast homing could be associated with the development of skin rash with IgA1-deposits in DH but not in CD.

Expression of standard CD44 in human colorectal carcinoma: association with prognosis

The aim of the present study was to evaluate the expression of standard CD44 (CD44s) in colorectal cancer (CRC), its relationship with clinicopathological characteristics, and its potential prognostic significance. CD44s levels were measured on immunohistochemistry in tumors and surrounding normal mucosa from 74 patients with primary colorectal carcinomas. The patients were followed for a median period of 37 months. Expression of CD44s in primary tumor and surrounding normal mucosa tissues was demonstrated in 100% (74/74) and 37.9% (28/74), respectively. The expression of CD44s in tumors was significantly associated with the depth of invasion (P = 0.034) and lymph node involvement (P = 0.031). A significant difference was observed between the overall survival and level of tumor CD44s expression, especially for stage IV carcinoma (P = 0.038). Multivariate analysis indicated that TNM stage (P = 0.020) and tumor CD44s expression (P = 0.008) were independent predictors of overall survival in adenocarcinomas. CD44s overexpression may be an independent unfavorable prognostic factor for overall survival in advanced CRC, especially stage IV disease. Further investigation, however, is necessary to assess the biological roles of CD44 in CRC, and validate their possible value as novel therapeutic targets.

Environmental cues, dendritic cells and the programming of tissue-selective lymphocyte trafficking

Lymphocytes are imprinted during activation with trafficking programs (combinations of adhesion and chemoattractant receptors) that target their migration to specific tissues and microenvironments. Cytokines contribute, but, for gut and skin, evolution has cleverly adapted external cues from food (vitamin A) and sunlight (ultraviolet-induced vitamin D3) to imprint lymphocyte homing to the small intestines and T cell migration into the epidermis. Dendritic cells are essential: they process the vitamins to their active metabolites (retinoic acid and 1,25(OH)(2)D3) for presentation with antigen to lymphocytes, and they help export environmental cues through lymphatics to draining lymph nodes, to program the trafficking and effector functions of naive T and B cells.

CD44s expression in resectable colorectal carcinomas and surrounding mucosa

BACKGROUND

CD44s (standard isoform) is a cell adhesion molecule belonging to the family of the hyaluronan-binding proteins. The CD44 family has been found to be overexpressed in epithelial tumors, where they are generally in relationship with tumor growth and metastasic properties. The aim of this work was to evaluate the membranous CD44s content in colorectal cancer and in healthy surrounding mucosa, its possible relationship with clinicopathological parameters, and its potential prognostic significance.

MATERIALS AND METHODS

Membranous CD44s levels were measured by an immunoenzymatic assay in tumors and surrounding mucosa samples from 72 patients with resectable colorectal carcinomas. The patients were followed for a mean time period of 30 months.

RESULTS

There was a wide variability of CD44s levels in tumor-surrounding mucosal samples (26.6-727 ng/mg protein) as well as in tumors (28.5-381 ng/mg protein). Tumor samples showed significantly higher CD44s levels (median: 99.1 ng/mg protein) than surrounding mucosal samples (81 ng/mg protein) (p=0.03). In the same way, CD44s levels in tumors as well as in surrounding mucosal samples were significantly higher in high S-phase tumors than in low S-phase tumors (p=0.001 for both). There was no significant relationship between tumor CD44s levels and patient's outcome. However, high levels of the glycoprotein in nonneoplastic surrounding mucosa were significantly (p=0.018) associated with a poor overall patient survival.

CONCLUSION

CD44s may play a role in the tumorogenesis of colorectal carcinomas. In addition, CD44s levels in tumor-surrounding mucosa may provide, in concert with some clinicopathological parameters, important information about prognostic evaluation of patients with resectable colorectal carcinomas.

A novel CD44 antibody identifies an epitope that is aberrantly expressed on acute lymphoblastic leukaemia cells

Previous studies have shown that the antibody 7H9D6 identifies CD44, a glycoprotein receptor for hyaluronic acid. 7H9D6 recognizes an epitope of CD44 that is not always present on CD44 molecules. The 7H9D6 antibody bound to the hyaluronic acid binding domain of CD44 and inhibited cell adhesion to immobilized hyaluronic acid. However, the expression of the 7H9D6 epitope was not sufficient for hyaluronic acid binding. Immunofluorescent staining with 7H9D6 revealed a punctate surface staining pattern, suggesting that CD44 molecules recognized by 7H9D6 are located in clusters on the cell surface. In contrast, other CD44 antibodies produced a uniform staining pattern. Early bone marrow B cells were negative for 7H9D6 but reactive with other CD44 monoclonal antibodies. In contrast, leukaemic cells from 65% of patients (28 of 43) with B lineage acute lymphoblastic leukaemia bound 7H9D6. Patients expressing the 7H9D6 epitope on their leukaemic cells had an increased risk of death (HR 3.5 95% CI 1.1-10.9, P = 0.029) and of disease relapse (HR 3.2 95% CI 1.2-8.5, P = 0.017) when corrected for white cell count. This antibody may be useful for the detection of residual disease in B lineage acute lymphoblastic leukaemia and as a prognostic indicator and for the study of CD44 function.

CD44 deficiency leads to enhanced neutrophil migration and lung injury in Escherichia coli pneumonia in mice

CD44 is a major cell-surface receptor for hyaluronic acid (HA), a glycosaminoglycan component of extracellular matrix. HA-CD44 interactions have been implicated in leukocyte extravasation into an inflammatory site. This study examined the role of CD44 in acute inflammatory responses during pneumonias induced by Escherichia coli and Streptococcus pneumoniae using CD44-deficient mice. In E. coli-induced pneumonia, neutrophil accumulation in the lungs and edema formation was increased by 84% and 88%, respectively, in CD44-deficient mice compared to wild-type mice. In contrast, no difference was observed between these genotypes in S. pneumoniae-induced pneumonia, and the HA content in the lungs decreased after instillation of S. pneumoniae, but not E. coli, in both genotypes. Studies to determine the mechanisms for this enhanced response showed that: 1) neutrophil apoptosis was not different between these two genotypes in either type of pneumonia; 2) CD44 deficiency resulted in enhanced mRNA expression of several inflammatory genes; and 3) CD44-deficient neutrophils migrated through Matrigel in response to chemoattractants faster and in greater numbers than wild-type neutrophils in vitro and this increase was in part dependent on HA content in the Matrigel. These data demonstrate that CD44 deficiency results in enhanced inflammation in E. coli but not S. pneumoniae-induced pneumonia, suggesting a previously unrecognized role for CD44 in limiting the inflammatory response to E. coli.

Glycosylation might provide endothelial zip codes for organ-specific leukocyte traffic into inflammatory sites

Inflammatory diseases are characterized by the leukocyte infiltration into tissues. L-selectin on lymphocytes and its endothelial glycosylated ligands are instrumental in the initiation of lymphocyte extravasation. Immunohistochemical stainings with monoclonal antibodies against functionally active glycan-decorated L-selectin ligands, ie, sialyl-Lewis x (sLex, 2F3, and HECA-452) or sulfated extended core 1 lactosamine (MECA-79), were performed on more than 400 specimen representatives for thyroiditis, myocarditis, psoriasis, vasculitis, ulcerative colitis, and their corresponding noninflamed tissues. The endothelial expression of sLex or sulfo sLex glycans in postcapillary venules was either absent or low in control tissues. The de novo induction of endothelial expression of sLex or sulfo sLex glycans was detected in all inflamed tissues. Furthermore, each organ carried its own modification of sLex or sulfo sLex glycans, ie, zip code. Our results suggest that these zip code glycans may provide means for organ selective leukocyte traffic that could be used in selective leukocyte traffic inhibition.

Cutaneous lymphocyte-associated antigen (CLA) expression in a lymphoblastoid mantle cell lymphoma presenting with skin lesions. Comparison with other clinicopathologic presentations of mantle cell lymphoma

BACKGROUND

Cutaneous lymphocyte-associated antigen (CLA) is a lymphocyte homing receptor selectively expressed by T cells of the cutaneous immune system and their malignant counterpart, that is to say, cutaneous T-cell lymphomas. However it is absent in the vast mayority of other T-cell malignancies and B-cell lineage lymphomas irrespective on primary tumor site.

METHODS

Expression of CLA was investigated on six cases of mantle cell lymphoma (MCL) which differed in their histopathological subtype (typical or blastic) and their tendency to infiltrate skin and/or central nervous system (CNS).

RESULTS

CLA immunostaining on neoplastic cells was only observed in a 61-year-old female suffering from a lymphoblastoid MCL which clinically presented with specific skin lesions and further developped CNS disease. In this patient, coexpression of CLA with MCL markers (CD20 and CD5) was confirmed by conventional immunohistochemistry and double immunofluorescence studies.

CONCLUSIONS

To our knowledge, CLA immunoreactivity on B-cell lymphomas has not beeen previously reported. The expression of this skin-related adhesion molecule on malignant MCL cells could explain the clinical behavior of our case which presented and relapsed with cutaneous lesions. However, CLA seems not to be a MCL marker nor a CNS-related adhesion molecule. The authors review the clinical and histopathological characteristics of MCL-specific skin lesions and their diagnostic clues based on cell morphology, immunohistochemistry and molecular investigations.

Immunotherapy in atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory disease involving the skin and often other organs and systems, mainly respiratory. A definitive general consensus on the AD pathogenesis has not yet been established, however several lines of evidence suggest that T-cells play a crucial role in priming AD early-stage lesions. Main topics involved in the disease pathogenesis have been reviewed, which considered the concept of local and systemic haemopoietic events as important contributors to allergic inflammation, a concept now achieving great acceptance. The recently recognised atopic nature of the skin inflammation in AD has raised increasing interest for treatment with allergen-specific immunotherapy. However, we only found eight studies using specific immunotherapy (SIT) in AD, two double-blind, placebo-controlled (DBPC) and six observational. One controlled and five observational reported favourable outcomes. The one unique study providing negative results was flawed by the ineffective oral route of extract administration. Despite being encouraging, the reported results do not allow definitive conclusions based on meta-analytic techniques because the amount and quality of information in the literature is not sufficient. The highly promising sub-lingual immunotherapy (SLIT) is discussed with its potential capability of controlling not only the skin lesion severity but also its capability of preventing the development of atopic dermatitis into asthma.

Coupling of osteopontin and its cell surface receptor CD44 to the cell survival response elicited by interleukin-3 or granulocyte-macrophage colony-stimulating factor

The receptors for interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) share a common beta subunit, the distal cytoplasmic domain of which is essential for the promotion of cell survival by these two cytokines. Genes whose expression is specifically induced by signaling through the distal cytoplasmic domain of this receptor beta subunit were screened by a subtraction cloning approach in derivatives of a mouse pro-B-cell line. One gene thus identified was shown to encode a protein highly homologous (with only 7 amino acid substitutions) to murine osteopontin (OPN), a secreted adhesion protein. Conditioned medium from cells expressing wild-type OPN, but not that from cells expressing a deletion mutant lacking residues 79 to 140, increased the viability of a non-OPN-producing cell line in the presence of human GM-CSF. Antibody blocking experiments revealed that OPN produced as a result of IL-3 or GM-CSF signaling was secreted into the medium and, through binding to its cell surface receptor, CD44, contributed to the survival-promoting activities of these two cytokines. Furthermore, coupling of the OPN-CD44 pathway to the survival response to IL-3 was also demonstrated in primary IL-3-dependent mouse bone marrow cells. These results thus show that induction of an extracellular adhesion protein and consequent activation of its cell surface receptor are important for the antiapoptotic activities of IL-3 and GM-CSF.

Systemic aspects of psoriasis. An integrative model based on intestinal etiology

Psoriasis can best be understood from a multifactorial approach that recognizes the systemic aspects of the disorder. Among the various factors thought to be involved in the etiology and pathogenesis of psoriasis, bowel pathology has assumed a noteworthy position in the literature. This article reviews the psoriasis/bowel connection with regard to abnormal bowel structure and physiology in psoriasis patients. Clinical implications of bowel involvement in psoriasis are discussed within the framework of an integrative medicine model that emphasizes natural therapeutics for addressing the systemic aspects of the illness.

Correlation of CD44S expression in renal clear cell carcinomas with subsequent tumor progression or recurrence

BACKGROUND

Recent reports have shown altered expression of CD44 in renal cell carcinomas. However, to the authors' knowledge there are no data correlating CD44 expression in renal cell carcinomas with subsequent tumor progression or recurrence, nor is there information about the presence of particular splice variants of CD44 in these tumors.

METHODS

The authors examined the immunohistochemical expression of CD44S, the standard isoform of CD44, in renal cell carcinomas from 43 patients using 2 different monoclonal antibodies, Mab2137 and Hermes-3. In addition, they stained the renal cell carcinomas with antibodies to 2 splice variants of CD44, CD44v3 and CD44v6.

RESULTS

Increased staining of renal clear cell carcinomas with Mab2137 was observed in high grade versus low grade tumors (45% vs. 0%, P = 0.013), whereas increased staining of clear cell carcinomas with Hermes-3 was noted in high stage versus low stage tumors (40% vs. 0%, P = 0.006). Few tumors stained with antibodies to CD44v3. Although increased expression of the splice variant CD44v6 was noted in papillary versus clear cell carcinomas, and increased staining of papillary carcinomas with Mab2137 and with antibodies to CD44v6 was noted for low stage versus high stage tumors, these differences did not achieve statistical significance. Clinical follow-up of at least 43 months was available for 26 patients. Six of these patients (five with clear cell carcinoma and one with papillary carcinoma) developed progressive or recurrent disease. The primary tumors from all 5 patients with progressive or recurrent clear cell carcinoma showed staining with Mab2137, whereas the primary tumors from only 2 of the 15 patients with at least 43 months follow-up and no evidence of progressive or recurrent clear cell carcinoma (13%) showed staining with Mab2137 (P = 0.001). Alternatively, 5 of 7 clear cell carcinomas (71%) that stained with Mab2137 were from patients who subsequently developed recurrence or progression, compared with 0 of 13 clear cell carcinomas that did not stain. Similar findings were not observed for papillary carcinomas, which appeared to be biologically distinct from clear cell carcinomas.

CONCLUSIONS

CD44S staining with Mab2137 correlates with progression or recurrence of clear cell renal cell carcinoma. CD44S may, therefore, play a pathogenetic role in tumor progression.

Patterns and significance of CD44 expression in lung allografts

BACKGROUND

Lung allograft rejection involves the interplay of multiple cellular populations, soluble mediators, and extracellular matrix proteins. The CD44 family of cell surface glycoproteins mediates a variety of cell-cell and cell-matrix interactions including lymphocyte homing to sites of antigenic challenge and fibroblast migration and invasion into extracellular matrix, processes integral to lung allograft rejection.

METHODS

We performed immunohistochemical staining for CD44 on biopsies from allograft recipients with differing rejection experiences: Group 1 (n = 5 patients/10 biopsies) never exceeded Grade A1 or B2 acute rejection (AR); Group 2 (n = 7 patients/26 biopsies) had 2 or more episodes of Grade A2 or higher AR and no obliterative bronchiolitis (OB); Group 3 (n = 6 patients/17 biopsies) had clinical and pathologic OB. Nine infected allograft biopsies, 8 near-normal lung sections (non-transplant controls), and 13 non-transplant biopsies showing bronchiolitis obliterans organizing pneumonia (BOOP), organizing diffuse alveolar damage (DAD), or usual interstitial pneumonia (UIP) were also studied.

RESULTS

Allograft biopsies demonstrated significantly more CD44 staining among lymphocytes, macrophages, Type II pneumocytes, and respiratory epithelial cells than non-transplant controls, while staining of lymphocytes, macrophages, and Type II pneumocytes did not differ significantly between allograft groups. Fibroblast CD44 staining in Group 3 biopsies significantly exceeded that of controls and Groups 1 and 2, and biopsies with AR and/or OB showed more fibroblast staining than biopsies with BOOP, organizing DAD, or UIP. Alveolar CD44-positive fibroblasts did not predict development of OB, while bronchial CD44-positive fibroblasts were followed in one case by OB.

CONCLUSIONS

These findings suggest that CD44 expression is characteristic of graft-infiltrating inflammatory cells and resident parenchymal cells, and may be related to the initiation and evolution of AR and OB.

Activation-dependent modulation of hyaluronate-receptor expression and of hyaluronate-avidity by human monocytes

During inflammation, activated monocytes (Mo) migrate into tissues where they interact with extracellular matrix components such as hyaluronate (HA), produced in high amounts at inflammatory sites. We determined whether Mo that had invaded sites of cutaneous inflammation bind HA and express the putative HA receptors CD44 isoforms, ICAM-1, or receptor for hyaluronate-mediated motility (RHAMM). In cutaneous inflammation, activated infiltrating Mo displayed high HA avidity and expressed epitopes encoded by CD44s, CD44 variant exons v3, v4, v5, v6, v7, and v9, and ICAM-1, but not RHAMM. We further investigated how activation affects the avidity of Mo for HA and which receptors were responsible for such binding. Mo freshly purified from human peripheral blood bound little HA and expressed CD44s but no epitopes encoded by CD44v exons, ICAM-1, or RHAMM. During short-term tissue culture, Mo upregulated their HA avidity and expression of ICAM-1, CD44s, and epitopes encoded by CD44v, all of which were further augmented by IFN-gamma or lipopolysaccharide, whereas RHAMM was not detectable. Thus in vitro activated Mo resembled Mo that had migrated to inflammatory sites in vivo. Lipolysaccharide or IFN-gamma-induced HA binding was inhibited by more than 90% with monoclonal antibodies directed against N-terminal HA binding domains of CD44s, but not by monoclonal antibodies against CD44v epitopes or ICAM-1. In conclusion, we show that upon in vitro or in vivo activation, Mo enhance their capacity to bind HA. This is critically dependent upon the expression ofCD44s epitopes. Regulated CD44-HA interactions may be important for the ability of Mo to migrate into and within sites of inflammation and for Mo effector functions.

CD44 Regulates Hematopoietic Progenitor Distribution, Granuloma Formation, and Tumorigenicity

CD44 is expressed in various isoforms on numerous cell types and tissues during embryogenesis and in the mature organism. CD44 may also be involved in tumor growth. To study the multiple roles of CD44, we abolished expression of all known isoforms of CD44 in mice by targeting exons encoding the invariant N-terminus region of the molecule. Surprisingly, mice were born in Mendelian ratio without any obvious developmental or neurological deficits. Hematological impairment was evidenced by altered tissue distribution of myeloid progenitors with increased levels of colony-forming unit–granulocyte-macrophage (CFU-GM) in bone marrow and reduced numbers of CFU-GM in spleen. Fetal liver colony-forming unit–spleen and granulocyte colony-stimulating factor mobilization assays, together with reduced CFU-GM in peripheral blood, suggested that progenitor egress from bone marrow was defective. In what was either a compensatory response to CD44 deficiency or an immunoregulatory defect, mice also developed exaggerated granuloma responses to Cryotosporidium parvum infection. Finally, tumor studies showed that SV40-transformed CD44-deficient fibroblasts were highly tumorigenic in nude mice, whereas reintroduction of CD44s expression into these fibroblasts resulted in a dramatic inhibition of tumor growth.

CD44 Regulates Hematopoietic Progenitor Distribution, Granuloma Formation, and Tumorigenicity

CD44 is expressed in various isoforms on numerous cell types and tissues during embryogenesis and in the mature organism. CD44 may also be involved in tumor growth. To study the multiple roles of CD44, we abolished expression of all known isoforms of CD44 in mice by targeting exons encoding the invariant N-terminus region of the molecule. Surprisingly, mice were born in Mendelian ratio without any obvious developmental or neurological deficits. Hematological impairment was evidenced by altered tissue distribution of myeloid progenitors with increased levels of colony-forming unit–granulocyte-macrophage (CFU-GM) in bone marrow and reduced numbers of CFU-GM in spleen. Fetal liver colony-forming unit–spleen and granulocyte colony-stimulating factor mobilization assays, together with reduced CFU-GM in peripheral blood, suggested that progenitor egress from bone marrow was defective. In what was either a compensatory response to CD44 deficiency or an immunoregulatory defect, mice also developed exaggerated granuloma responses to Cryotosporidium parvum infection. Finally, tumor studies showed that SV40-transformed CD44-deficient fibroblasts were highly tumorigenic in nude mice, whereas reintroduction of CD44s expression into these fibroblasts resulted in a dramatic inhibition of tumor growth.

An essential role for CD44 variant isoforms in epidermal Langerhans cell and blood dendritic cell function

Upon antigen contact, epidermal Langerhans cells (LC) and dendritic cells (DC) leave peripheral organs and home to lymph nodes via the afferent lymphatic vessels and then assemble in the paracortical T cell zone and present antigen to T lymphocytes. Since splice variants of CD44 promote metastasis of certain tumors to lymph nodes, we explored the expression of CD44 proteins on migrating LC and DC. We show that upon antigen contact, LC and DC upregulate pan CD44 epitopes and epitopes encoded by variant exons v4, v5, v6, and v9. Antibodies against CD44 epitopes inhibit the emigration of LC from the epidermis, prevent binding of activated LC and DC to the T cell zones of lymph nodes, and severely inhibit their capacity to induce a delayed type hypersensitivity reaction to a skin hapten in vivo. Our results demonstrate that CD44 splice variant expression is obligatory for the migration and function of LC and DC.

CD44 expression in benign and malignant nevomelanocytic lesions

CD44 is an integral membrane glycoprotein that is a principal receptor for hyaluronan and plays a role in cell-extracellular matrix interactions. Recent studies of melanomas in mouse models have suggested that increased CD44 expression by these tumors may relate to metastatic potential. Immunohistochemical expression of CD44 (standard [s] and variant [v6]) in benign and malignant nevomelanocytic lesions was assessed in formalin-fixed, paraffin-embedded tissue and was correlated with histological parameters and prognostic factors. Cases included benign nevi (three junctional, four compound, five intradermal, five blue, six Spitz, one deep penetrating), architecturally disordered (dysplastic) nevi (three, and primary (22) and metastatic melanomas (eight). All of the benign lesions showed diffuse and essentially uniform membrane staining of CD44s in nevomelanocytic cells, regardless of lesion size, depth, or extent of dermal involvement. In contrast, semiquantitative analysis (0 to 3+) of the primary melanomas showed heterogeneous and decreased staining of CD44s, which inversely correlated with lesion size (-0.569) and depth of invasion (-0.622 and -0.617 for Breslow's depth and Clark's level, respectively). These results were significant at P < .05. CD44s expression in metastases paralleled that of their respective primaries. None of the benign nevomelanocytic lesions showed CD44v6 staining. In contrast, all of the malignant nevomelanocytic lesions showed cytoplasmic staining of the tumor cells. Pretreatment with chondroitinase did not alter CD44s staining. CD44s expression by immunohistochemical determination is uniform in benign nevomelanocytic lesions. Malignant melanomas show decreased, heterogeneous staining that inversely correlates with increasing size, depth, and level of invasion. CD44 expression may be a prognostic indicator in malignant melanomas. Tumor staining with anti-chondroitin sulfate monoclonal antibodies suggests that CD44s may be expressed as a chondroitin sulfate proteoglycan in primary melanomas.

Human cutaneous dendritic cells migrate through dermal lymphatic vessels in a skin organ culture model

The capacity to migrate from peripheral tissues, where antigen is encountered, to lymphoid organs, where the primary immune response is initiated, is crucial to the immunogenic function of dendritic cells (DC). The skin is a suitable tissue to study migration. DC were observed to gather in distinct nonrandom arrays ("cords") in the dermis upon culture of murine whole skin explants. It is assumed that cords represent lymphatic vessels. Using a similar organ culture model with human split-thickness skin explants, we investigated migration pathways in human skin. We made the following observations. 1) Spontaneous emigration of Langerhans cells took place in skin cultured for 1-3 d. Nonrandom distribution patterns of strongly major histocompatibility complex class II-expressing DC (cords) occurred in cultured dermis. A variable, yet high (>50%) percentage of these DC coexpressed the Birbeck granule-associated antigen "Lag." Ultrastructurally, the cells corresponded to mature DC. 2) Electron microscopy proved that the dermal structures harboring the accumulations of DC (i.e., cords) were typical lymph vessels. Moreover, markers for blood endothelia (monoclonal antibody PAL-E, Factor VIII-related antigen) and markers for cords (strong major histocompatibility complex class II expression on nonrandomly arranged, hairy-appearing cells) were expressed in a mutually exclusive pattern. 3) On epidermal sheets we failed to detect gross changes in the levels of expression of adhesion molecules (CD44, CD54/ ICAM-1, E-cadherin) on keratinocytes in the course of the culture period. The reactivity of a part of the DC in the dermal cords with Birbeck granule-specific monoclonal antibody "Lag" suggests that the migratory population is composed of both epidermal Langerhans cells and dermal DC. We conclude that this organ culture model may prove helpful in resolving pathways and mechanisms of DC migration.

CD44 and melanocytic tumors: a possible role for standard CD44 in the epidermotropic spread of melanoma

CD44 is a polymorphic family of cell membrane glycoproteins that mediate cell-matrix and cell-cell interactions involved in the mechanisms of tumor invasion and metastasis, and are subject to differential regulation during normal and malignant cell growth. We have investigated immunohistochemically the expression of CD44S and the variant isoforms CD44v3 and CD44v6 in paraffin-embedded tissue from 5 Spitz nevi, 3 compound melanocytic nevi, 2 blue nevi, 6 primary melanomas, 15 cutaneous metastases (three epidermotropic, nine dermal and three ulcerated) and 10 lymph node metastases of melanoma. Melanocytes were extensively positive for CD44S in primary melanomas and benign melanocytic proliferations. Among 15 cases of cutaneous metastases of melanoma, the three epidermotropic metastases, as well as one of the three ulcerated ones were positive for CD44S. CD44S expression was diminished or totally absent in six of the nine dermal metastases, in two of the ulcerated metastases and in seven of the ten lymph node metastases. CD44v3 and CD44v6 melanocytic expression was absent in all the lesions studied. According to our results, selective retention of CD44S expression by melanocytes in epidermotropic metastases of melanoma seems to indicate that preservation of CD44S may contribute to the intraepidermal spread of melanoma.

Endothelial cell adhesion molecules in psoriasis

Skin biopsies from patients with psoriasis and normal controls were examined for the expression of cell adhesion molecules including intercellular adhesion molecule-1 (ICAM-1), endothelial leukocyte adhesion molecule-1 (ELAM-1), HECA-452 and 4D10, using an immunoperoxidase techique. This study demonstrates that psoriatic skin exhibits a wide variety of markers of endothelial cell activation which are either induced or increased in expression (ICAM-1, ELAM-1 & 4D10). Moreover, ICAM-1 & HECA-452 are also expressed on leukocytes. These antigens may facilitate the adhesion of inflammatory cells to endothelium and antigen-presenting cells in psoriatic skin. Thus, they may play a role in faciliating the infiltration of leukocytes into psoriatic skin.

Expression of monoclonal antibody HECA-452-defined E-selectin ligands on Langerhans cells in normal and diseased skin

The cutaneous lymphocyte-associated antigen recognized by the monoclonal antibody HECA-452 has been thought to play a major role in the homing of memory T-cell subsets to the skin by virtue of its ability to bind to E-selectin of dermal microvascular endothelial cells. Considering that the homing of different leukocyte populations to the skin may involve similar mechanisms, we studied the expression of HECA-452-reactive molecules on CD1a+ epidermal Langerhans cells. Immunofluorescence double-labeling of cryostat sections and epidermal sheets of normal skin revealed HECA-452 immunoreactivity on a subpopulation of dermal and epidermal CD1a+ cells, whereas upon flow-cytometric analysis of epidermal single cell suspensions virtually all CD1a+ cells bound HECA-452 antibodies. We observed a marked upregulation of HECA-452-antigen expression on CD1a+ epidermal cells and a pronounced increase in the number of HECA-452+/CD1a+ dermal cells in lesional skin from inflammatory and neoplastic lymphocytic skin diseases, compared to normal skin. The molecule detected by the HECA-452 antibody on Langerhans cells is neuraminidase sensitive and contains a CD15 (LewisX) carbohydrate backbone. Because Langerhans cells react with the sialyl-LewisX-specific antibody CSLEX1, it is very likely that the HECA-452-reactive structure is or contains sialyl-LewisX. Our data are compatible with the view that i) resident epidermal Langerhans cells upregulate HECA-452-antigen expression due to the cytokine profile generated in the disease process or ii) that Langerhans cell precursors express HECA-452-antigens and show an enhanced immigration into lesional skin. The characterization of HECA-452+ cells in peripheral blood may not only clarify this issue but may also help to identify the still elusive Langerhans cell-precursor.

Isolation and characterization of gamma delta T lymphocyte cell lines from Sinclair swine peripheral blood

Sinclair miniature swine represent a breed of miniature swine which display a significant incidence of inheritable melanoma which undergo a developmentally regulated spontaneous regression. In an attempt to characterize the host cellular immune response to the melanoma, lymphocyte cell lines have been generated from peripheral blood and designated as peripheral blood lymphocyte cell lines (PBLCLs). The cell lines were expanded in vitro without the addition of exogenous mediators, cloned by limiting dilution, and characterized by flow microfluorimetry, Western, and Northern blot analysis. The cell lines were shown to be CD2-, CD4-, CD8-, and slg-, a phenotype consistent with a null cell population described in swine. The null cell population in swine has been reported to consist of a subpopulation of cells which express the gamma delta T cell receptor (TCR) heterodimer, swine gamma delta T lymphocytes. The PBLCLs were further analyzed by flow microfluorimetry and observed to express the IL-2R, swine MHC Class II antigens, and the endothelial lymphocyte adhesion marker (CD44), which can function as a homing receptor for the skin. In addition, the PBLCLs were observed to express the antigen which is recognized by mAb 86D, an antibody that has been reported to recognize an external epitope on a subset of gamma delta TCR bearing swine T lymphocytes. Western blot analysis of Triton X-114 phase fractions of a PBLCL revealed a protein recognized by the W6 antibody, an antibody which recognizes a conserved region of the C delta chain. Furthermore, Southern and Northern blot analysis indicated that the PBLCL have rearranged the TCR gamma chain gene and express mRNA from the TCR gamma and delta chain genes prior to and following treatment with ionomycin or Concanavalin A. Therefore, the data indicates that the PBLCLs represent swine gamma delta T lymphocyte cell lines which should enable us to enhance our understanding of the role of gamma delta T lymphocytes in the porcine immune system.

Skin-homing T lymphocytes: detection of cutaneous lymphocyte-associated antigen (CLA) by HECA-452 in normal human skin

The immigration of circulating T cells into specific tissues is directed by the interaction between adhesion molecules on lymphocyte subpopulations and their ligands on vascular endothelium. Of these, endothelial leucocyte adhesion molecule (ELAM-1), weakly expressed in normal human skin (NHS), seems to be the counter-structure for cutaneous lymphocyte-associated antigen (CLA). CLA is a 200 kDa cell-surface glycoprotein of which the sugar moieties sialyl Le(a) and sialyl Le(x) are the possible epitopes recognized by the monoclonal antibody HECA-452. HECA-452 was originally described as a marker for lymphoid organ high endothelial cells, but 16% of peripheral-blood-derived T cells react with this antibody. We studied the expression of CLA on the cellular constituents of the skin immune system (SIS). By applying immunohistochemical double staining, 41% of CD3+ T cells, 44% of CD4+ T cells and 31% of CD8+ T cells were found to express CLA. Keratinocytes, CD1a+ Langerhans cells (LC) and endothelial cells did not express HECA-452 in significant numbers in NHS. Monocytes were found to express HECA-452 in 14% of CD68+ cells. CLA expression was present on a relatively low percentage of T cells and subsets localized distant from NHS vessels, suggesting loss of the molecule during further migration after transendothelial passage. However, intraepidermal T cells expressed CLA in similar percentages to T cells localized directly perivascularly. Our findings support the notion that CLA expression by T cells is associated with their homing into cutaneous structures.

CD44 antibody stimulates adhesion of peripheral blood T cells to keratinocytes through the leukocyte function-associated antigen-1/intercellular adhesion molecule-1 pathway

Close contact between T lymphocytes and keratinocytes is an important feature of many inflammatory skin diseases. In vitro studies showed that stimulation of keratinocytes with interferon-gamma or tumor necrosis factor-alpha and of T cells with phorbol esters results in a leukocyte function-associated antigen (LFA)-1/intercellular adhesion molecule (ICAM)-1-mediated adhesion. The present study was performed to investigate the role of the CD44 molecule in keratinocyte/T-cell binding. The CD44 class of lymphocyte adhesion receptors is involved in lymphocyte binding to high endothelial venules and to extracellular matrix compounds and is therefore important in lymphocyte recirculation and homing. Moreover, CD44 can act as a co-stimulating signal in T-cell activation and promotes homotypic adhesion of in vitro cultured CD3-stimulated T cells. Using a cell adhesion assay a sixfold increase in T-cell/keratinocyte adhesion was found after pre-incubating the T cells with anti-CD44. This increased adhesion was found to require an intact cytoskeleton, to be energy and magnesium dependent, and could be completely inhibited by anti-LFA-1 and anti-ICAM-1. Pretreatment of T cells with hyaluronic acid, a ligand for CD44 and an extracellular matrix compound in the dermis and epidermis, did not affect T-cell/keratinocyte adhesion.

Prevention of tumor metastasis formation by anti-variant CD44

A splice variant of CD44 (CD44v) originally discovered on metastases of a rat pancreatic adenocarcinoma (BSp73ASML) has been shown by transfection to confer metastatic behavior to nonmetastatic tumor cells (Günthert U., M. Hofmann, W. Rudy, S. Reber, M. Zöller, I. Haussmann, S. Matzku, A. Wenzel, H. Ponta, and P. Herrlich. 1991. Cell. 65:13). A monoclonal antibody (mAb), 1.1ASML, to the metastasis-specific domain of the CD44v molecule retards growth of lymph node and lung metastases of the metastatic tumor line BSp73ASML, and can efficiently prevent formation of metastases by the transfected line. The antibody is only effective when given before lymph node colonization. Anti-CD44v does not downregulate the expression of CD44v, and prevention of metastatic growth by anti-CD44v is not due to activation of any kind of immune defense. We suggest that the mAb interferes with proliferation of metastasizing tumor cells in the draining lymph node, most probably by blocking a ligand interaction. The interference with metastatic spread will greatly facilitate the exploration of the function of CD44v and, in particular, may also open new strategies for the therapy of human metastases.

Differential expression of the HECA-452 antigen (cutaneous lymphocyte associated antigen, CLA) in cutaneous and non-cutaneous T-cell lymphomas

The monoclonal antibody HECA-452 identifies an antigen that is primarily expressed on high endothelial venules, the preferred site of lymphocyte extravasation in lymphoid tissues, and also on a subpopulation of myelomonocytic cells and some T-cells. We investigated the expression of the HECA-452 antigen, also called the cutaneous lymphocyte associated antigen, in primary cutaneous and primary non-cutaneous T-cell non-Hodgkin's lymphomas. The tumour cells of cutaneous T-cell non-Hodgkin's lymphomas were positive in 53% of cases, while only 5% of the non-cutaneous lymphomas were positive. These differences were also present in morphologically identical tumours. Thus, the tumour cells in six out of 10 primary cutaneous anaplastic large cell T-cell lymphomas were positive, while they were positive in none of 24 primary non-cutaneous anaplastic large cell T-cell lymphomas. In general, primary cutaneous and primary nasal T-cell non-Hodgkin's lymphomas were devoid of HECA-452 positive high endothelial venules, whereas most nodal T-cell non-Hodgkin's lymphomas contained HECA-452 positive high endothelial venules. These observations suggest that the HECA-452 antigen might be related to a skin-associated type of lymphoid tissue and to lymphomas originating in the skin. However, the results of HECA-452 expression in secondary sites, and the clinical data of the primary cutaneous large cell lymphomas did not support the concept that HECA-452 is functionally involved in homing to the skin, or that loss of the HECA-452 antigen is related to tumour progression of primary cutaneous T-cell lymphomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adhesion molecules and malignant gliomas: implications for tumorigenesis

Adhesion molecules, a family of cell-surface molecules, are likely to be of central importance in mediating cell-extracellular matrix and specific cell-cell interactions within both neoplastic and inflammatory sites. The recently discovered expression of adhesion molecules on glioma cells, tumor-infiltrating lymphocytes, and endothelial cells within the tumor offers insight into the molecular basis of the interactions both between the glioma cell and surrounding heterologous cell types within the tumor environment, and between the tumor cell and the extracellular matrix. Such interactions suggest that these molecules may play roles in the homing of immune cells to these tumors and in regulating the extent of local tumor invasion. The ability to modulate adhesion molecule expression on either immune cells or their respective ligands on gliomas provides an approach to modify cell-cell interactions that may be used to increase tumor kill by the immune system. A similar approach in the modulation of adhesion molecules involved in tumor cell adhesion to the extracellular matrix or endothelial cells may be a method to limit local invasion in these lesions.