Identification of glioma-associated antigen MUC 2-63 as CD44

Monoclonal antibody MUC 2-63 recognises neurogenic tumours and has been used successfully for radioimaging human malignant gliomas. We now show that the MUC 2-63 antigen has the same tissue distribution and molecular weight range as the CD44 antigen and confirm the identity of these two molecules in blocking studies using MUC 2-63 and the CD44 anti-framework antibody F10-44-2. Thus not only MUC 2-63 but also other anti-CD44 monoclonal antibodies should prove useful in imaging and, perhaps, therapy of brain tumours.

A quantitative analysis of antigen-presenting cell function: activated B cells stimulate naive CD4 T cells but are inferior to dendritic cells in providing costimulation

Ligation of CD28 on CD4 Th1 clones and freshly isolated mixtures of naive and memory CD4 T cells triggered their T cell receptors (TCR) is sufficient to induce the costimulatory signals necessary for interleukin 2 (IL-2) production by these cells. CTLA-4-reactive ligands expressed on antigen-presenting cells (APC) are critical in providing costimulatory signals to these T cell populations. We demonstrate that these activation characteristics apply equally to purified naive CD4 T cells. Because B cell blasts express CTLA-4-reactive ligands and high levels of adhesion and major histocompatibility complex class II molecules, they would be expected to engage both the TCR and CD28 and consequently stimulate IL-2 production by naive CD4 T cells. Using purified populations of cells in limiting dilution cultures, we have carried out a quantitative analysis of the interaction between naive CD4 T cells and either activated B or dendritic cells. We demonstrate that B cell blasts stimulate a high frequency of naive CD4 T cells. Slight differences in TCR signaling efficiency between the two APC types were observed. Even at optimal peptide concentrations, however, the amount of IL-2 made by individual T cells was fourfold lower in response to B cell blasts than to dendritic cells. This relative deficiency of activated B cells was due to their inability to optimally costimulate naive CD4 T cells.

The significance of CD44 in human pancreatic cancer: I. High expression of CD44 in human pancreatic adenocarcinoma

The CD44 cell surface glycoprotein, which is the adhesion molecule of lymphocytes, has been suggested to be an important factor for the metastatic potential and invasive ability of cancer. We demonstrated the expression of CD44 in human pancreatic adenocarcinoma cells and normal cells by using flow cytometry (FACS-can) and immunohistological staining. CD44 was highly expressed in human pancreatic adenocarcinoma cells, while it was little expressed in normal human pancreas cells. These results indicate that the quantitative analysis of CD44 expression may be a useful diagnostic tool for pancreatic cancer.

Expression of CD44 variant isoforms in normal and neoplastic cells of the lung

CD44 is a cell surface receptor that has been implicated in lymphocyte homing, hematopoiesis, cell migration and possibly also tumor metastasis. In the present study, expression of CD44 variant (CD44v) isoforms was analyzed in 23 lung cancer specimens together with corresponding normal lung tissues by Southern blot analysis coupled with reverse transcription-polymerase chain reaction amplification. We found that CD44v isoforms were expressed in all lung cancer specimens, suggesting a possible role in the establishment of metastases by these highly malignant tumors, but normal tissues were also positive. This is in marked contrast to the previous reports of essentially negligible expression of CD44v isoforms in normal colon and breast, and suggests a physiological function in the lung.

Anti-(glioma surface antigen) monoclonal antibody G-22 recognizes overexpressed CD44 in glioma cells

We raised an anti-glioma monoclonal antibody, named G-22, that specifically recognizes a human glioma-associated surface antigen. Proven to be useful for target imaging of malignant gliomas after radioisotope labeling and cerebrospinal fluid diagnosis by enzyme-linked immunospecific assay, G-22 was found to immunoprecipitate an 85-kDa glycoprotein of the human glioma U-251MG cell. We purified this antigen by G-22-coupled cyanogenbromide-activated Sepharose affinity chromatography, and sequence analysis demonstrated that the 54 amino acid residues were identical to positions 55-108 of human CD44. The results show that the smallest spliced form (85 kDa) of CD44 is strongly expressed in glioma cells.

Distribution of hyaluronan in bull reproductive organs

To study the expression of hyaluronan in male reproductive organs and the origin of seminal plasma hyaluronan, we stained various parts of the bull reproductive tract for hyaluronan using a biotinylated probe derived from cartilage proteoglycan (bHABC). The potential loss of hyaluronan during tissue processing was checked with a novel technique by blotting frozen tissue sections on nitrocellulose and staining the blots with bHABC. In the same tissues the CD44 receptor was visualized by Hermes 1 antibody. The testes showed only traces of hyaluronan, whereas both the epithelium and the connective tissue of seminal vesicle, prostate, Cowper's gland, and epididymis were positive in bHABC staining. Hyaluronan was localized on the basolateral surfaces of these epithelial cells. The secretions inside the seminal vesicle and in the ducts of prostate and Cowper's gland were HA-positive, whereas the luminal contents of seminiferous tubules and epididymis were unstained both in paraffin sections and in the in situ blocks. The data indicate that hyaluronan in seminal plasma originates from the accessory sex glands. The co-localization of CD44 with hyaluronan in the basolateral surfaces of the accessory gland epithelia and its absence from other epithelia with little or no hyaluronan supports its role as a hyaluronan receptor.

Direct in vivo gene transfer into porcine myocardium using replication-deficient adenoviral vectors

BACKGROUND

Efficient methods of introducing genes into myocardial cells must be developed before local somatic cell gene therapy can be implemented against myocardial disease. Although adenoviral (Ad5) vectors have been used to target rodent hearts and plasmid DNA has been directly injected into the myocardium of rats and dogs, the amounts of recombinant protein produced by these procedures have not been reported, and adenoviral vectors have not been used in large mammalian hearts.

METHODS AND RESULTS

Replication-deficient recombinant adenoviral vectors carrying either the luciferase or lacZ reporter genes were injected directly into the ventricular myocardium of adult domestic swine for evaluation of reporter gene expression. This procedure did not affect regional myocardial function as assessed by systolic wall thickening using ultrasonic crystals. Luciferase activity was detected 3 days after injection, increased markedly at 7 days, and then declined progressively at 14 and 21 days. Luciferase production was comparable in the right and left ventricular walls and increased with increasing amounts of virus, reaching 61 +/- 21 ng at the highest dose examined (3.6 x 10(9) plaque-forming units). The injection of 200 micrograms of plasmid DNA (pRSVL) produced levels of luciferase comparable to 1.8 x 10(8) plaque-forming units of recombinant Ad5; however, when normalized to the number of genes injected, the adenovirus was 140,000 times more efficient than plasmid DNA. Histochemical analysis of beta-galactosidase activity produced by a second Ad5 vector demonstrated that nearly all (> 95%) of the stained cells were cardiomyocytes and that the percentage of cardiomyocytes infected by the virus could be quite high in microscopic regions adjacent to the needle track (up to 75% in fields of 60 to 70 cells); however, Ad5-infected cells were rarely observed farther than 5 mm from the injection site. Furthermore, the Ad5 vector induced pronounced leukocytic infiltration that was far in excess of that seen after injection of vehicle alone.

CONCLUSIONS

This study demonstrates for the first time that direct intramyocardial injection of replication-deficient adenovirus can program recombinant gene expression in the cardiomyocytes of a large animal species with relevance to human physiology. The efficiency of adenovirus-mediated gene transfer is far superior to that of plasmid DNA injection, and this method appears to be capable of producing more recombinant protein. However, the cell-mediated immune response to the Ad5 vector and the limited distribution of reporter gene expression suggest that less immunogenic recombinant vectors and more homogeneous administration methods will be required before Ad5 vectors can be successfully used for phenotypic modulation.

Vascular adhesion molecules and initial development of inflammation in clinically healthy human keratinized mucosa around teeth and osseointegrated implants

Expression of vascular cell adhesion molecules (HEV-CAMs) by capillary loops represents an early step necessary for leukocyte extravasation and subsequent migration to sites of inflammation. The purpose of this investigation was to compare, the presence and distribution of ICAM-1, ELAM-1, VCAM-1 and PECAM-1 expression in the microvasculature of healthy gingiva and peri-implant keratinized mucosa. The selected HEV-CAMs were detected by a three stage immunoperoxidase technique in serial sections from clinically characterized sites. Biopsies were qualitatively and quantitatively analyzed. All biopsies displayed a small inflammatory infiltrate subjacent to the most coronal extension of the junctional epithelium. HEV-CAMs were expressed both in the sulcular and oral aspects of biopsies. Intensity of ICAM-1, ELAM-1 and VCAM-1 staining, however, was consistently higher in the region of the infiltrated connective tissue subjacent to the most coronal extension of the junctional epithelium. Only a fraction of microvascular loops were positive for ICAM-1, ELAM-1 or VCAM-1 when compared to the constitutively expressed PECAM-1. No significant differences were observed between gingiva and keratinized peri-implant mucosa. It was concluded that in healthy gingiva or peri-implant mucosa 1. HEV-CAM expressing capillary loops were in close topographic association with the inflammatory infiltrate; 2. only a fraction of capillary loops are activated to express ICAM-1, ELAM-1 and VCAM-1 at any given time; and 3. HEV-CAM expression in the periodontium may be influenced by local factors.

Generation of polarized antigen-specific CD8 effector populations: reciprocal action of interleukin (IL)-4 and IL-12 in promoting type 2 versus type 1 cytokine profiles

We have generated primary effector populations from naive CD8 T cells in response to antigen and determined their patterns of cytokine secretion upon restimulation. The effect of exogenous factors on the effector generation was examined and compared with responses of antigen-specific CD4 effectors generated under comparable conditions. CD8 cells from bm1 mice were stimulated with C57BL/6 (B6) antigen presenting cells (APCs) bearing allogeneic class I and CD8 cells from female severe combined immunodeficiency (SCID) B6 mice, transgenic for a T cell receptor alpha/beta (TCR-alpha/beta) that recognizes H-Y on Db, were stimulated with APCs from male mice. In parallel, CD4 cells from bm12 mice were stimulated with alloantigen and CD4 cells from V beta 3/V alpha 11 TCR transgenics were stimulated with a peptide of pigeon cytochrome c on IEk. T cells from both transgenic mice were of naive phenotype whereas normal mice contained 10-20% memory cells. Effector CD8 populations generated were L-selectin low, CD45RB high, and CD44 high. Naive CD8 cells from SCID anti-H-Y mice made little or no cytokine immediately upon stimulation in contrast to naive CD4 which produced large amounts of interleukin 2 (IL-2). Both populations, however, generated primary effectors over 4-5 d that made substantial quantities of many cytokines upon restimulation. Both CD8 and CD4 effectors produced similar patterns of cytokines with alloantigen or specific antigen. Cytokines present during naive CD8 stimulation influenced the cytokine secretion profile of the effectors, as previously shown for CD4 cells, although secretion by CD8 effectors was generally lower than that of CD4 effectors. CD8 cells cultured with IL-2 alone made predominantly interferon gamma (IFN-gamma) and no IL-4 or IL-5, similar to CD4 cells. Priming with IFN-gamma increased IFN-gamma secretion from CD4 effectors, but had little if any effect on CD8 cells. In contrast, priming with IL-12 generated CD8 effectors, as well as CD4 effectors, producing elevated quantities of IFN-gamma, with similar levels from both the CD4 and CD8 populations. The presence of IL-4 during effector cell generation promoted synthesis of IL-4 and IL-5 from both CD8 and CD4 cells while downregulating IFN-gamma secretion. CD8 cells made only small amounts of IL-4, more than 100-fold less than CD4 cells, whereas significant levels of IL-5 were induced, only 3-10-fold lower than from CD4.(ABSTRACT TRUNCATED AT 400 WORDS)

Rapid establishment of a stable IL-4/IFN-gamma production profile in the antigen-specific CD4+ T cell response to protein immunization

Development of the antigen-specific murine T cell response to immunization with keyhole limpet hemocyanin (KLH) in adjuvant has been monitored with direct limiting dilution analysis of CD4+ cells in draining lymph nodes (LN) and measurement of the cytokines produced by their clonal progeny. In vivo, the response to immunization suggested a major role for IL-4 and a minor role for IFN-gamma since IL-4 mRNA levels increased and IFN-gamma mRNA levels declined in LN over the first 3 days, and KLH-specific serum antibodies were mainly of IgG1 class with lower levels of IgE and IgG2a. Antigen-specific clonogenic cells were first detected in LN at day 4, at which time they comprised approximately 8% of the total CD4+ LN cell pool, declining to 1-2% from day 7 until at least 6 weeks after immunization. These clonogenic cells expressed high levels of surface CD44 (Pgp-1) both early and late in the in vivo response. Over the whole of the time span from day 4 to 6 weeks after immunization, most antigen-specific cells gave rise to clones that secreted IL-4 and a smaller proportion gave rise to IFN-gamma-secreting clones. By contrast, polyclonally activated CD4+ cells from untreated mice preferentially gave rise to clones with the converse cytokine profile. We conclude that a stable ratio of antigen-specific CD4+ cells committed to IL-4 or IFN-gamma synthesis is established within the first 4 days after KLH immunization and, contrary to prediction, does not evolve towards a more restricted cytokine profile during the primary response.

Expression of two isoforms of CD44 in human endometrium

The distribution of the cell-surface adhesion glycoprotein CD44 in human endometrium was examined by immunofluorescence using six monoclonal antibodies to epitopes common to all forms of the molecule, and by reverse transcription-polymerase chain reaction (RT-PCR). Immunoreactivity was observed throughout the menstrual cycle in stroma, vessels, glandular, and luminal epithelium. Variations in staining intensity were observed, especially in the epithelial compartment. CD44 was also expressed strongly by decidualized stromal cells of first-trimester pregnancy. No systematic variation of immunoreactivity was observed with stages of the normal cycle, but a fraction (25%) of the specimens lacked reactivity in the epithelium. To determine the molecular size of the epithelial isoform, an immunoprecipitation technique was developed using surface-radioiodinated, detergent-extracted glands. This indicated the presence at the cell surface of a single dominant CD44E species with an approximate molecular mass of 130 kDa. RT-PCR was used to investigate the isoforms present in whole endometrial tissue, isolated gland fragments, and Ishikawa endometrial carcinoma cells. Complementary DNA produced from total endometrial mRNA was PCR-amplified across the splice junction between exons 5 and 15. Transcripts corresponding to the hyaluronate receptor CD44H as well as a larger isoform were identified. CD44H was absent, or very scarce, in cDNA from purified gland epithelium. In contrast, Ishikawa cells expressed this form abundantly. The glands and Ishikawa cells also expressed CD44E containing sequences encoded by exons 12, 13, and 14. These data demonstrate the presence of CD44 in human endometrium and decidua, and show that different isoforms of CD44 are associated with tissue compartments in which different functional roles can be anticipated.

Distribution of hyaluronan in the epiphysial growth plate: turnover by CD44-expressing osteoprogenitor cells

In the present study, we have examined the distribution of both hyaluronan and its receptor, CD44, during the process of endochondral ossification in the mouse tibia. Histochemical staining revealed that a large amount of hyaluronan was present in the lacunae located in the zone of hypertrophy, but it was greatly reduced or absent from the zone of erosion. In addition, hyaluronan was present in the cytoplasm of osteoprogenitor cells located in the zone of erosion. These cells also expressed CD44 on their surfaces, as revealed by double-label immunohistochemistry. These results suggested that the osteoprogenitor cells may use CD44 to bind and internalize hyaluronan, and subsequently degrade it with lysosomal enzymes. To test this possibility, we examined the human cell line, MG-63, which closely resembles osteoprogenitor cells. These cells produced several different forms of CD44, as determined by western blotting (85, 116 and 150 kDa). In addition, the binding of isotopically labeled hyaluronan to detergent extracts of these cells was blocked by a monoclonal antibody to CD44. Similarly, the degradation of hyaluronan by these cultured cells was also inhibited by a monoclonal antibody to CD44. To determine if these cells could remove hyaluronan from the growth plate, the cells were cultured directly on top of thin sections of the epiphysial region of long bone. After 16 hours, the sections were stained for hyaluronan. The MG-63 cells removed significant amounts of hyaluronan present in the zone of hypertrophy, and this effect was blocked by an excess of soluble hyaluronan and by a monoclonal antibody to CD44.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of the cell adhesion molecule CD44 in gastric adenocarcinomas

CD44, an integral membrane glycoprotein expressed by many cell types, serves as the principal transmembrane hyaluronate receptor and may be a determinant of metastatic and invasive behavior in carcinomas. The expression of CD44 in 23 gastric adenocarcinoma and 12 peptic ulcer disease (PUD) resection specimens and gastric carcinoma cell lines HS746t and KATO III was examined by immunohistochemistry using the murine monoclonal antibody A3D8 on formalin-fixed, paraffin-embedded tissue or cells. Western blot analysis of whole cell lysates of KATO III and HS746t cells showed protein bands at 85 to 90 kd with KATO III cells expressing an additional band at 145 kd. In normal stomach gastric epithelium was negative. In PUD foveolar epithelium was focally positive, but staining did not correlate with the extent of gastritis. In carcinoma cases intensity of staining was progressively stronger comparing intestinal metaplasia with dysplasia with intramucosal carcinoma. Invasive carcinoma was invariably more strongly positive than dysplasia or intramucosal carcinoma. Twelve adenocarcinomas were weakly positive and 11 were strongly positive. The staining intensity of metastases (12 cases) was the same or weaker than the primary tumor. For the 12 patients whose carcinomas were weakly positive, mean length of survival for the six who died was 23.3 months. Five of the 11 patients whose carcinomas strongly expressed CD44 died within the study period with a mean length of survival of 11.0 months. A key consequence of CD44 overexpression in gastric carcinomas may be development of the invasive phenotype and strong expression may indicate a poorer prognosis.

The formation of human synovial joint cavities: a possible role for hyaluronan and CD44 in altered interzone cohesion

During fetal development, cavitation occurs within the primitive skeleton along planes destined to become the articular surfaces of synovial joints. A histochemical study of human fetal limbs was undertaken to identify the cell types involved in this cavitation and the possible role of interactions between cells and extracellular matrix. Cryostat sections were stained with antibodies to CD68, factor VIII related antigen, prolyl hydroxylase, beta 1 integrin, VCAM-1, proliferating cell nuclear antigen, chondroitin-4 sulphate, chondroitin-6-sulphate, hyaluronan synthase and CD44. Similar sections were reacted for uridine diphosphoglucose dehydrogenase (UDPGD) and acid phosphatase activity. Hyaluronan was demonstrated using an aggrecan core protein hyaluronan binding region probe. Macrophages were present prior to cavitation in the periphery of joint interzones but not at the presumptive joint line in the central interzone. Fibroblastic cells were present throughout. Absence of local VCAM-1 expression indicated that cavitation was temporally distinct from full fibroblast-like synoviocyte differentiation. CD44 was expressed by interzone cells at all stages. Staining for hyaluronan and hyaluronan synthase, but not chondroitin sulphates was present in the interzone before and at the time of cavitation. UDPGD activity was increased in a narrow band of cells at the presumptive joint line prior to cavitation. These findings suggest that joint cavitation is dependent on the behaviour of fibroblastic cells and/or adjacent chondrocytes, rather than macrophages. Since UDPGD activity is involved in hyaluronan synthesis, it is proposed that joint cavitation is facilitated by a rise in local hyaluronan concentration in an area of tissue where cohesion is dependent on the interaction between cellular CD44 and extracellular hyaluronan. As proposed by Toole et al. (1984) such a local rise in hyaluronan concentration may lead to a switch from intercellular cohesion to dissociation, leading to tissue cavitation.

Expression of integrins and CD44 isoforms in non-Hodgkin's lymphomas: CD44 variant isoforms are preferentially expressed in high-grade malignant lymphomas

Low- and high-grade malignant non-Hodgkin's lymphomas have been investigated by immunohistochemistry for their expression of various integrins and CD44 isoforms. Comparison with the expression patterns obtained in non-malignant adult lymph nodes revealed the following differences: alpha 6 and beta 4 integrins were expressed in several high-grade malignant lymphomas to a lower degree than in both the low-grade malignant lymphomas and the normal lymph nodes; all other integrins (alpha 2, alpha 4, alpha 5, alpha v, beta 1, beta 2, beta 3, and beta 7) did not exhibit significant differences in the expression levels between malignant and non-malignant tissues. The standard isoform of CD44 (CD44s) was highly expressed in all lymphoid tissues. Using CD44 exons-specific monoclonal antibodies, CD44 variant isoforms were not detected in non-malignant lymph nodes and were detected only rarely in low-grade malignant lymphomas. In contrast, high-grade malignant lymphomas expressed several CD44 variant isoforms, which included the products from the variant exons 3v, 6v, and 9v, but not 4v. Specifically, detection of exon 3v and 6v products indicates a more aggressive phenotype.

Localization of endoglin, a transforming growth factor-beta binding protein, and of CD44 and integrins in placenta during the first trimester of pregnancy

Endoglin is an integral membrane glycoprotein that binds transforming growth factor-beta 1 (TGF beta 1) with high affinity and is predominantly expressed on human endothelial cells. Characterization of this homodimeric protein from human term placenta has shown that it is particularly abundant on the syncytiotrophoblast. Immunofluorescence staining of sections of first trimester placenta now reveals that endoglin is found at even higher levels on the syncytiotrophoblast of samples ranging from 6 to 12 wk of gestation. Very low levels are observed on the undifferentiated cytotrophoblast cells that can be identified by their expression of the alpha 6 beta 4 integrin, a receptor for laminin. Within the villi, blood vessels and stromal cells are negative for endoglin but positive for alpha 1 beta 1 integrin, a receptor for collagens and laminin. Stromal cells also express CD44, a hyaluronic acid receptor. Of particular interest is the up-regulation of endoglin expression in the transition from polarized undifferentiated to non-polarized intermediate cytotrophoblasts (CTB) as the cells align in columns to invade the uterus. This occurs in parallel with the acquisition of alpha 5 beta 1 integrin (fibronectin receptor) and precedes the loss of alpha 6 beta 4 integrin. CD44 and alpha 1 beta 1 integrin are noticeably absent from the CTB within the columns but are expressed at very high levels throughout the placental bed. Endoglin is undetectable within the decidua; thus, intermediate CTB that have invaded the placental bed express alpha 5 beta 1 integrin and cytokeratins but not endoglin.(ABSTRACT TRUNCATED AT 250 WORDS)

An invariant T cell receptor alpha chain is used by a unique subset of major histocompatibility complex class I-specific CD4+ and CD4-8- T cells in mice and humans

The mouse thymus contains a mature T cell subset that is distinguishable from the mainstream thymocytes by several characteristics. It is restricted in its usage of T cell receptor (TCR) V beta genes to V beta 8, V beta 7, and V beta 2. Its surface phenotype is that of activated/memory cells. It carries the natural killer NK1.1 surface marker. Furthermore, though it consists entirely of CD4+ and CD4-8- cells, its selection in the thymus depends solely upon major histocompatibility complex (MHC) class I expression by cells of hematopoietic origin. Forced persistence of CD8, in fact, imparts negative selection. Here, we have studied the TCR repertoire of this subset and found that, whereas the beta chain V-D-J junctions are quite variable, a single invariant alpha chain V alpha 14-J281 is used by a majority of the TCRs. This surprisingly restricted usage of the V alpha 14-J281 alpha chain is dependent on MHC class I expression, but independent of the MHC haplotype. In humans, a similar unusual population including CD4-8- cells can also be found that uses a strikingly homologous, invariant alpha chain V alpha 24-JQ. Thus, this unique V alpha-J alpha combination has been conserved in both species, conferring specificity to some shared nonpolymorphic MHC class I/peptide self-ligand(s). This implies that the T cell subset that it defines has a specialized and important role, perhaps related to its unique ability to secrete a large set of lymphokines including interleukin 4, upon primary stimulation in vitro and in vivo.

Hyaluronan receptors are expressed on human malignant mesothelioma cells but not on normal mesothelial cells

Hyaluronan-binding sites were demonstrated on the cell surface of three malignant mesothelioma cell lines derived from human tumors using either [3H]hyaluronan or fluorescein-tagged hyaluronan. No hyaluronan-binding activity was observed on normal human mesothelial cells. The absence of hyaluronan receptors on normal human mesothelial cells was not due to a down-regulation by endogenously synthesized hyaluronan, since no binding sites appeared when the cells were cultured under conditions known to suppress hyaluronan synthesis (in starvation medium containing either hydrocortisone or n-butyrate) or to degrade endogenously synthesized hyaluronan (in the presence of Streptomyces or testicular hyaluronidase). The binding of [3H]hyaluronan on mesothelioma cells could be partially inhibited by prior incubation of the cells with trypsin, indicating that the hyaluronan-binding site is a protein. The binding sites on human malignant mesothelioma cells were shown to be saturable with about 54,000 hyaluronan molecules (M(r) 1.4 x 10(6)) bound per cell with a Kd of 0.3 x 10(-9) M. The binding was specific for hyaluronan inasmuch as a number of other macromolecules gave negligible inhibition of the binding. High molecular weight preparations of hyaluronan inhibited the binding more effectively than low molecular weight preparations; hyaluronan oligosaccharides down to a length of six monosaccharide units showed competing activity. The hyaluronan receptor appeared to be related to CD44 (a cell surface glycoprotein previously suggested to function as a hyaluronan receptor) since Hermes-1 monoclonal antibodies which inhibit the binding of hyaluronan to CD44 blocked a major part of the binding of hyaluronan to the mesothelioma cells. However, there was no strict correlation between the hyaluronan-binding activity on the mesothelioma cell lines tested and the levels of CD44 molecules on their cell surface, suggesting that only a subfraction of the CD44 molecules bound hyaluronan or that other hyaluronan-binding proteins also exist on those cells. The presence of hyaluronan receptors on mesothelioma cells, but not on their normal counterparts, may be of importance for the migration of the transformed cells in hyaluronan-enriched matrices and for their ability to form metastases.

Normal human tissues, in addition to some tumors, express multiple different CD44 isoforms

At least 20 different isoforms of the human CD44 lymphocyte-homing receptor/hyaluronan receptor have been described to date that arise from the differential splicing of up to 10 alternative exons (termed v1-v10) encoding the membrane-proximal extracellular domain. Although numerous analyses at the mRNA level have indicated tissue-specific expression of CD44 variants, few analyses have been performed at the protein level because of limited availability of suitable monoclonal antibodies. Recently, however, exon-specific monoclonal antibodies have been generated using bacterial fusion proteins, and these have been reported to detect high levels of vCD44 containing the v6 exon on human tumors. Together with earlier evidence linking this particular exon with tumor metastasis in the rat, these latter experiments have led to the interpretation that v6 splice variants play a causative role in tumor dissemination. In this paper we describe the use of a new and comprehensive panel of CD44 exon-specific monoclonal antibodies generated against a recombinant CD44(v3-10)-immunoglobulin chimera to study vCD44 expression in a large number of normal and neoplastic tissues. We show that the expression of vCD44 varies greatly among different human tumors and that some express either very low levels of vCD44 or no CD44 at all. Furthermore, we demonstrate that expression is not limited to isoforms containing the v6 exon but includes variants carrying v3, v4/5, and v8/9. Additionally, normal epithelial tissues are shown to express considerable levels of these same vCD44 isoforms. Such results argue against a ubiquitous role for vCD44 isoforms in promoting tumor growth and metastasis.

Transient loss of proteins carrying Kell and Lutheran red cell antigens during consecutive relapses of autoimmune thrombocytopenia

A patient is described in whom two consecutive relapses of autoimmune thrombocytopenic purpura (AITP) were associated with loss of red cell antigens of the Kell and Lutheran blood group systems respectively. During the second relapse the glycoprotein CD44 and to a lesser extent the LW antigen were also depressed. Both relapses were associated with concomitant production of IgG antibody recognizing high-frequency determinants on the corresponding antigen-carrying protein. Blocking of antigen sites by these antibodies was not the cause of reduced antigen expression, because immunoblotting studies showed absence of Kell protein during the first relapse, and Lutheran protein during the second. On both occasions the red cell changes reverted to normal with disappearance of the antibody as the AITP entered remission. There was no evidence of clonal lymphocyte expansion as demonstrated using immunoglobulin JH and T cell receptor beta chain probes.

Biology of fetal wound healing: hyaluronate receptor expression in fetal fibroblasts

Fetal tissue repair is rapid, relatively scarless, and proceeds in an environment rich in hyaluronic acid. Understanding the interaction of hyaluronic acid (HA) with the reparative cells may provide important insight into the remarkable process of fetal wound healing. Therefore, the purpose of this study was to characterize the HA receptor (a member of the CD44 family of cell surface glycoproteins) and its density on the cell surface of fetal fibroblasts. HA receptor expression on both adult and fetal fibroblasts was first studied by Western blot analysis. Autoradiographs of the blots were assessed by densitometry to quantitate the relative amounts of the HA receptor. It appears that the HA receptor expressed on both adult and fetal rabbit dermal fibroblasts is a 56-kd protein. After normalizing for total protein concentration using the Bradford protein assay, the fetal HA receptor density was found to be approximately four-fold greater than that of the adult. The same adult and fetal fibroblasts were then studied by flow cytometry, using a fluorescence-activated cell sorter (FACS). Relative fluorescence was representative of HA receptor density. Corroborating the authors' earlier result with the Western blot analysis, the FACS analysis showed that the fetal fibroblasts had 2.5 times the fluorescence of the adult cells. It is concluded that, in comparison to adult fibroblasts, fetal fibroblasts have an increased density of cell-surface HA receptor.

CD44H expression by human neuroblastoma cells: relation to MYCN amplification and lineage differentiation

The human CD44 cell surface glycoprotein has been involved in a variety of functions including lymphocyte homing, extracellular cell matrix attachment, and tumor metastasis. Due to the alternative splicing of the single gene, a large family of different variants or isoforms is generated. Several reports have indicated an up-regulation of CD44 variant (v) isoforms in malignant process, conferring metastatic potential to non-metastatic cells. Neuroblastoma is a tumor characterized by an aggressive and metastatic behavior in advanced stages with amplification of the MYCN protooncogene. In this report we show that the CD44 standard molecule is highly expressed in 100% of stage I-III, IVs neuroblastomas and ganglioneuromas but only in a subset of stage IV tumors. In contrast, no expression of CD44 was detected on MYCN amplified stage IV tumors, thus demonstrating a highly significant negative relationship between MYCN amplification and CD44 expression in neuroblastoma. The expression of CD44 on neuroblastoma cultured cell lines was not shown to be related to MYCN amplification but rather linked to the S-type, schwann/glial differentiation lineage. Immunochemical analysis of tumor samples with anti-CD44v3 and -v6 antibodies and Northern blot analysis of mRNA from cell lines with probes spanning exons 4-10 did not reveal any expression of splice variants on neuroblastomas of all stages and cell lines, thus ruling out a major role of these isoforms in neuroblastoma progression and metastasis.

Clones of tumor cells derived from a single primary human lung tumor reveal different patterns of beta 1 integrin expression

Previously we reported that over 75% of human non-small cell lung cancers overexpress the beta 1 integrin VLA-2 on their surface and show an increase in the mRNA encoding the alpha-2 chain of this integrin. These results suggested the possibility that the overproduction and overexpression of one or more of the beta 1 integrin may be involved in the pathogenesis of human lung tumors by modulating the invasive and/or metastatic potential of the tumor. We report here the generation and characterization of multiple clones of tumor cells derived from the primary culture of cells obtained from biopsy tissue of an aggressive human squamous cell lung tumor. We show that these tumor clones (or clonotypes) exhibit seven different yet stable phenotypes with respect to the expression of five members of the beta 1 integrin family. These results illustrate that a primary human lung tumor consists of multiple subpopulations of cells that while indistinguishable by ultrastructure are heterogeneous with respect to their beta 1 integrins. The availability of these distinct tumor clonotypes derived from a single tumor biopsy have made it possible to test the assumption that the beta 1 integrins play a role in tumor progression. The feasibility of this approach is demonstrated here by the intravenous inoculation of different human tumor clonotypes into severe combined immunodeficient (scid) mice. Our preliminary results with a pair of tumor clonotypes differing in VLA-1 and VLA-2 expression level reveal that the clonotype with high level of VLA-1 and VLA-2 displays a substantial increase in the experimental engraftment and metastasis of the human tumor cells in scid mice.

Expression of CD44 in normal human versus tumor endometrial tissues: possible implication of reduced expression of CD44 in lymph-vascular space involvement of cancer cells

Alternatively spliced variants of the CD44 molecule have been found to be associated with invasive and metastatic potential of cancer cells and poor prognosis in several types of carcinoma. We have examined expression of CD44 in normal and cancerous tissues of the endometrium as well as in cell lines established from patients with endometrial cancers by the combination of reverse transcription-polymerase chain reaction and Southern blot hybridization and by cell surface staining with antibodies to CD44. Of eight cancer cell lines tested, two lines, HOOUA and HEC50B, both of which are possibly potential candidates for metastasis, expressed a very small amount of mRNA for CD44. Variant forms of CD44 were expressed in 9 of 11 (81.8%) normal endometria, whereas 8 of 47 (17.0%) endometrial carcinomas showed expression of the variants. Hyperplasia samples displayed the variant expression in 42.9% of specimens (the value was between those of the normal and cancerous cells) and none of 3 in Müllerian mixed tumors. There was a significant difference in frequencies of CD44 variant expression between normal and cancerous tissues. Furthermore, lymph-vascular space involvement of cancer cells was observed to be statistically significant in the CD44-negative group as opposed to the positive group. Reverse transcription-polymerase chain reaction and Southern blot hybridization clearly demonstrated that normal endometrial tissues express the standard CD44 form as well as the variant form. Immunohistochemical examination of normal endometrium revealed that intense staining was seen on the gland cells at the basement membrane side, and less intense staining was seen between the gland cells. These results suggest that CD44 could play important roles in the function of normal endometrium and that reduced CD44 expression might be related to the metastasis of endometrial cancer cells through lymph-vascular space.

Surface protein expression and messenger RNA-splicing analysis of CD44 in uterine cervical cancer and normal cervical epithelium

Variant CD44 has recently been shown to serve as a metastasis marker in human breast cancer. Certain variant epitopes on primary tumors predict poor survival probabilities for the patients. In this study, immunohistochemical analysis of 16 uterine cervical carcinomas showed strong expression of several CD44 variant epitopes in all samples. In normal cervical epithelia from 5 patients, expression of these epitopes was restricted to particular cell layers, with expression being strong in basal and spinal cells but absent in superficial cells. Fifteen of 16 cancer samples were stained strongly with an antibody which recognizes one particular CD44 epitope that is encoded by both variant exons v7 and v8. This epitope was not detectable in normal cervical epithelium. CD44-mRNA splicing analysis showed qualitative and quantitative differences between malignant and normal tissues with a much more complex splice pattern and high expression of a large CD44 isoform containing variant exons v3 to v10 (including the v7/v8 transition epitope) in about one-half of the cancer samples. Interestingly, patients with lymph node metastases were in this group only. These differences in CD44 epitope expression and mRNA splicing in cervical carcinoma reveal dynamic changes in CD44 expression during carcinogenesis. Such changes could provide metastatic cells with a selective advantage during the carcinogenic process. Furthermore, the v7/v8 epitope may be suitable for screening early stages of cervical cancer.