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PubMed2003

Involvement of transmembrane domain interactions in signal transduction by alpha/beta integrins.

The alpha and beta subunits of alpha/beta heterodimeric integrins function together to bind ligands in the extracellular region and transduce signals across cellular membranes. A possible function for the transmembrane regions in integrin signaling has been proposed from structural and computational data. We have analyzed the capacity of the integrin alpha(2), alpha(IIb), alpha(4), beta(1), beta(3), and beta(7) transmembrane domains to form homodimers and/or heterodimers. Our data suggest that the integrin transmembrane helices can help to stabilize heterodimeric integrins but that the interactions do not specifically associate particular pairs of alpha and beta subunits; rather, the alpha/beta subunit interaction constrains the extramembranous domains, facilitating signal transduction by a promiscuous transmembrane helix-helix association.

Amino Acid Motifs↗
PubMed2001

In situ demonstration of intraepithelial lymphocyte adhesion to villus microvessels of the small intestine.

The recirculation of lymphocytes through the intestinal mucosa is important for specific immune defense, but the origin and differentiation of intraepithelial lymphocytes (IEL) are not fully understood. The present study therefore used intravital microscopy to investigate the migration of IEL to the villus mucosa and Peyer's patches of the small intestine. IEL were separated from inverted murine small intestine and mesenteric lymph node (MLN) T cells were also isolated. The adhesion of fluorescence-labeled lymphocytes to postcapillary venules (PCV) of Peyer's patches and arcade microvessels of small intestinal villi was observed after injection. In some experiments, the effect of antibodies against adhesion molecules on cell kinetics were investigated. IEL time-dependently accumulated in villus microvessels of the small intestine, whereas few MLN cells did. Few IEL adhered to the PCV of Peyer's patches. IEL were shown to express alpha(E)beta(7)-integrin but not L-selectin. The accumulation of IEL in villus archade was significantly inhibited by antibody against beta(7)-integrin or mucosal addressin cell adhesion molecules (MAdCAM)-1, but not by alpha(E)-integrin. The combined blocking of beta(7)-integrin and MAdCAM-1 further attenuated the sticking of IEL in this area, although it did not entirely block the IEL adherence. The adherence of CD4(+) or TCRalphabeta IEL to villus microvessels was significantly greater than that of CD4(-) or TCRgammadelta IEL. It was demonstrated in situ for the first time that IEL adhered selectively to the villus microvessels of the small intestine partly via beta(7) and MAdCAM-1.

Animals↗
PubMed2004

Advanced glycation endproducts interefere with integrin-mediated osteoblastic attachment to a type-I collagen matrix.

The adhesion of osteoblasts to bone extracellular matrix, of which type-I collagen constitutes >85%, can modulate diverse aspects of their physiology such as growth, differentiation and mineralisation. In this study we examined the adhesion of UMR106 rat osteoblast-like cells either to a control (Col) or advanced-glycation-endproduct-modified (AGEs-Col) type I collagen matrix. We investigated the possible role of different integrin receptors in osteoblastic adhesion, by co-incubating these cells either with beta-peptide (conserved sequence 113-125 of the beta subunit of integrins) or with two other peptides, RGD (Arg-Gly-Asp) and DGEA (Asp-Gly-Glu-Ala), which are recognition sequences for the alpha-subunits of alpha(1,5)beta(1) and alpha(2)beta(1) integrins. Collagen glycation inhibited the adhesion of UMR106 osteoblasts to the matrix (40% reduction versus Col, P > 0.001). beta-Peptide showed a dose- and glycation-dependent inhibitory effect on adhesion, and at a concentration of 100 microM decreased the attachment of UMR106 cells to both matrices (42% to Col, P<0.001and 25% to AGEs-Col, P<0.01). The synthetic peptides RGD (1mM) and DGEA (5mM) inhibited the attachment of UMR106 cells to Col (30 and 20%, P > 0.01 and P< 0.001, respectively), but not to AGEs-Col. beta-Peptide induced an increase in UMR106 cell clumping and a decrease in cellular spreading, while DGEA increased spreading with cellular extensions in multiple directions. These results indicate that both alpha and beta integrin subunits participate in osteoblastic attachment to type-I collagen, probably through the alpha(1,5)beta(1) and alpha(2)beta(1) integrins. AGEs-modification of type-I collagen impairs the integrin-mediated adhesion of osteoblastic cells to the matrix, and could thus contribute to the pathogenesis of diabetic osteopenia.

Animals↗
PubMed2006

Two types of transmembrane homomeric interactions in the integrin receptor family are evolutionarily conserved.

Integrins are heterodimers, but recent in vitro and in vivo experiments suggest that they are also able to associate through their transmembrane domains to form homomeric interactions. Two fundamental questions are the biological relevance of these aggregates and their form of interaction in the membrane domain. Although in vitro experiments have shown the involvement of a GxxxG-like motif, several crosslinking in vivo data are consistent with an almost opposite form of interaction between the transmembrane alpha-helices. In the present work, we have explored these two questions using molecular dynamics simulations for all available integrin types. We have tested the hypothesis that homomeric interactions are evolutionary conserved, and essential for the cell, using conservative substitutions to filter out nonnative interactions. Our results show that two models, one involving a GxxxG-like motif (model I) and an almost opposite form of interaction (model II) are conserved across all alpha and beta integrin types, both in homodimers and homotrimers, with different specificities. No conserved interaction was found for homotetramers. Our results are completely independent from experimental data, both during molecular dynamics simulations and in the selection of the correct models. We rationalize previous seemingly conflicting findings regarding the nature of integrin interhelical homomeric interactions.

Amino Acid Motifs↗
PubMed2004

Identification of integrin beta subunit mutations that alter heterodimer function in situ.

We conducted a genetic screen for mutations in myospheroid, the gene encoding the Drosophila betaPS integrin subunit, and identified point mutants in all of the structural domains of the protein. Surprisingly, we find that mutations in very strongly conserved residues will often allow sufficient integrin function to support the development of adult animals, including mutations in the ADMIDAS site and in a cytoplasmic NPXY motif. Many mutations in the I-like domain reduce integrin expression specifically when betaPS is combined with activating alphaPS2 cytoplasmic mutations, indicating that integrins in the extended conformation are unstable relative to the inactive, bent heterodimers. Interestingly, the screen has identified alleles that show gain-of-function characteristics in cell culture, but have negative effects on animal development or viability. This is illustrated by the allele mys(b58); available structural models suggest that the molecular lesion of mys(b58), V409>D, should promote the "open" conformation of the beta subunit I-like domain. This expectation is supported by the finding that alphaPS2betaPS (V409>D) promotes adhesion and spreading of S2 cells more effectively than does wild-type alphaPS2betaPS, even when betaPS is paired with alphaPS2 containing activating cytoplasmic mutations. Finally, comparisons with the sequence of human beta8 suggest that evolution has targeted the "mys(b58)" residue as a means of affecting integrin activity.

Alleles↗
PubMed2001

Beta-integrin of Anopheles gambiae: mRNA cloning and analysis of structure and expression.

We have isolated an mRNA encoding a beta integrin subunit of the malaria mosquito Anopheles gambiae. Our analysis predicts a protein that is very similar to betaPS, the fruitfly orthologue. The gene is expressed during all developmental stages and it is found in all body parts, including the midgut. Finally, the expression of the gene does not seem to be modulated during blood meals, except for a substantial increase 48 h posthaematophagy, when digestion is nearly complete.

Amino Acid Sequence↗
PubMed2006

Localization of extracellular matrix receptors on the chondrocyte primary cilium.

A single primary cilium is found in chondrocytes and other connective tissue cells. We have previously shown that extracellular matrix (ECM) macromolecules such as collagen fibers closely associate with chondrocyte primary cilia, and their points of contact are characterized by electron-opaque plaques suggesting a direct link between the ECM and the cilium. This study examines the expression of receptors for ECM molecules on chondrocyte primary cilia. Embryonic chick sterna were fluorescently labeled with antibodies against alpha and beta integrins, NG2, CD44, and annexin V. Primary cilia were labeled using acetylated alpha-tubulin antibody. Expression of ECM receptors was examined on chondrocyte plasma membranes and their primary cilia using immunofluorescence and confocal microscopy. All receptors examined showed a punctate distribution on the plasma membrane. alpha2, alpha3, and beta1 integrins and NG2 were also present on primary cilia, whereas annexin V and CD44 were excluded. The number of receptor-positive cilia varied from 8/50 for NG2 to 43/50 for beta1 integrin. This is the first study to demonstrate the expression of integrins and NG2 on chondrocyte primary cilia. The data strongly suggest that chondrocyte primary cilia have the necessary machinery to act as mechanosensors, linking the ECM to cytoplasmic organelles responsible for matrix production and secretion.

Animals↗
PubMed2004

Bovine respiratory syncytial virus infection influences the impact of alpha- and beta-integrin-mediated adhesion of peripheral blood neutrophils.

Neutrophil migration into the airways and pulmonary tissue is a common finding in bovine respiratory syncytial virus (BRSV) infections. Although neutrophil trans-endothelial migration in general depends on beta2-integrins, alternative integrins such as the alpha4-integrins have been implicated. In this study, rolling and firm adhesion of peripheral blood neutrophils isolated from healthy and BRSV-infected calves to tumour necrosis factor (TNF)-alpha activated pulmonary endothelium was investigated under flow conditions in vitro. For neutrophils obtained from healthy animals, inhibition of the beta2-integrin reduced firm adhesion to 63% and inhibition of alpha4-integrin to 73% compared with untreated controls. Inhibition of both integrins reduced firm adhesion to 25%. Rolling velocity, which is used as a parameter for integrin involvement in neutrophil rolling, increased 1.7-fold by blocking beta2-integrin and was significantly augmented to 2.5-fold by blocking both alpha4- and beta2-integrins. For neutrophils obtained from BRSV-infected animals, however, rolling velocities at 10 days after infection (p.i.) were not influenced by blocking adhesion of alpha4- and beta2-integrins, indicating that these integrins did not support neutrophil rolling. In addition, the inhibition of firm adhesion by blocking both alpha4- and beta2-integrins was reduced significantly 9 days post-infection, resulting in a residual 68% neutrophil binding at 9 days p.i. Non-blocked firm adherence was not reduced, indicating that binding was achieved by other mechanisms than through alpha4- and beta2-integrins. These results demonstrate an important function for alpha4- and beta2-integrins in rolling and firm adherence of bovine neutrophils, to TNF-alpha-activated endothelium and show the dynamic use of these integrins for adhesion and migration by neutrophils in the course of BRSV infection.

Animals↗
PubMed1999

Alpha9 and beta8 integrin expression correlates with the merger of the developing mouse eyelids.

As previously reported, alpha9 integrin is expressed between the merged or fused eyelids of mice at birth, and changes in alpha9 localization occur during lid opening. To determine whether alpha9 and/or additional integrin subunits mediate the emergence and temporary fusion of the eyelids, immunofluorescence and confocal microscopy were used to evaluate the localization of various integrin subunits in the developing ocular surface of the mouse. No detectable beta5, beta6, or beta7 integrins were observed on the epithelia of the ocular surface. alpha2, alpha3, alphav, and beta1 integrins were most abundant in the basal cells beginning at 13.5 days post conception and remained primarily localized to the basal cell layers throughout development. beta4 was localized at the basal surface of the epidermal basal cells beginning at 13.5 days post conception but was not found on the corneal epithelial basal cells until after birth. alpha9 and beta8 integrins were present on suprabasal cells of the epidermis at the leading edge of the eyelid before merger and on the epithelial bridge that forms immediately after these tissues merge, suggesting that they play a role in the initial fusion of the epithelial tissues of the eyelid and in stabilizing the epithelial junction. After birth and into adulthood, beta8 was retained within the suprabasal cell layers of the epidermis, whereas alpha9 became localized to the basal cells of the epidermis, the conjunctiva, and the limbus. The lack of co-localization of beta4 with either alpha9 or beta8 in double-labeling studies suggests that alpha9 and beta8 are restricted to the lateral and apical aspects of those cells in which they are expressed. The presence of tenascin-C and laminin-5 at the epithelial junction site suggests that alpha9: tenascin-C and beta4: laminin-5 interactions may play a role in stabilizing the fusion between lids early on but do not appear to be involved in the movement of the lids across the cornea. The data presented identify specific integrins and matrix proteins that are likely to mediate eyelid fusion.

Animals↗
PubMed2000

Cell-cell adhesion via the ECM: integrin genetics in fly and worm.

Integrins are essential for the development of the two genetically tractable invertebrate model organisms, the nematode worm Caenorhabditis elegans and the fruit fly Drosophila melanogaster. Just two integrins are present in C. elegans: one putative RGD binding integrin alphapat-2betapat-3, corresponding to Drosophila alphaPS2betaPS and vertebrate alpha5beta1, alphaVbeta1 and alpha8beta1, and one putative laminin binding integrin alphaina-1betapat-3, corresponding to Drosophila alphaPS1betaPS and vertebrate alpha3beta1, alpha6beta1 and alpha7beta1. In this review, the function of this minimal set of integrins during the development of these two invertebrates is compared. Despite the differences in bodyplan and developmental strategy, integrin adhesion to the extracellular matrix is required for similar processes: the formation of the link that translates muscle contraction into movement of the exoskeleton, cell migration, and morphogenetic interactions between epithelia. Other integrin functions, such as regulation of gene expression, have not yet been experimentally demonstrated in both organisms. Additional proteins have been characterised in each organism that are essential for integrin function, including extracellular matrix ligands and intracellular interacting proteins, but so far different proteins have been found in the two organisms. This in part represents the fact that the characterisation of the full set of interacting proteins is not complete in either system. However, in other cases different proteins appear to be used for similar functions in the two animals. The continued use of genetic approaches to identify proteins required for integrin function in these two model organisms should lead to the identification of the minimal set of conserved components that form integrin adhesive structures.

Animals↗
PubMed1996

Identification of a binding site for integrin alphaEbeta7 in the N-terminal domain of E-cadherin.

The integrin alphaEbeta7, which is predominantly expressed on mucosal T lymphocytes, has recently been shown to recognize the cell adhesion molecule, E-cadherin, on epithelial cells. We have carried out mutations on E-cadherin, involving domain deletions as well as substitutions of specific amino acids, in order to identify the sites recognized by the integrin. Binding of alphaEbeta7 required the presence of the first two N-terminal domains of E-cadherin. Deletion of extracellular domains 3 and 4 or truncation of the cytoplasmic domain of E-cadherin had no consequence on integrin binding. Substitution of a glutamic acid in the BC loop of the Ig structure of the fist, N-terminal, domain of E-cadherin abrogated binding of alphaEbeta7. This mutation did not appear to affect the conformation of the domain nor the pattern of expression of E-cadherin on the cell surface. Synthetic peptides encompassing the first domain of E-cadherin had very little inhibitory effect on the interaction with alphaEbeta7. Our results highlight structural dissimilarities between recognition of E-cadherin by alphaEbeta7 and recognition of other members of the IgSF by integrins and show that the heterophilic (integrin binding) and homophilic sites in the N-terminal domain of E-cadherin are distinct.

Amino Acid Sequence↗
PubMed1988

Immunocytochemical studies of endothelial cells in vivo. II. Chicken aortic and capillary endothelial cells exhibit different cell surface distributions of the integrin complex.

Frozen sections of chicken tissues containing aortic and capillary endothelial cells were immunolabeled with two mouse monoclonal antibodies directed to different epitopes of the chicken integrin beta-chain. Integrin is an integral membrane protein complex that is believed to mediate a transmembrane linkage between the extracellular matrix and the actin cytoskeleton. In immunofluorescence experiments with semi-thin frozen sections, the aortic endothelial cells were labeled for integrin all around their surfaces, whereas capillary endothelial cells of heart and kidney were labeled only on their basal surfaces. At the immunofluorescence level of resolution, the distribution of integrin appeared to be correlated with that of F-actin in double-labeling experiments with NBD-phallacidin. These different distributions of integrin on the two types of endothelial cells were definitively confirmed by immunoelectron microscopic labeling with the monoclonal antibodies on ultra-thin frozen sections. These results therefore indicate that the luminal surfaces, as well as the underlying cytoskeleton of capillary endothelial cells, are significantly different in structure from those of aortic endothelial cells. These differences may reflect the vastly different hemodynamic stress to which the two types of endothelial cells are subjected, and in addition may mediate different adhesion properties of the luminal surfaces of the two cell types.

Animals↗
PubMed2005

Human gingival fibroblast integrin subunit expression on titanium implant surfaces.

BACKGROUND: Implant surface characteristics have been shown to modify cell behavior and regulate integrin expression. Integrin expression and resultant integrin-mediated cellular activity are essential components of tissue healing and homeostasis. Although both osseous and soft tissue healing around dental implants are critical to clinical success, there is limited information available on the effect of implant surfaces on integrin expression in soft tissues. Therefore, the aim of this study was to examine integrin expression for gingival fibroblasts on titanium surfaces and the influence of titanium surface roughness on integrin expression and cell morphology. METHODS: Human gingival fibroblasts were cultured on smooth (polished) and rough (sand-blasted acid-etched) titanium surfaces and a cell culture plastic (control) surface. To analyze integrin expression, total RNA was isolated from experimental and control cells, and levels of integrin subunit mRNA were assessed by reverse transcription-polymerase chain reaction (RT-PCR) using primers specific for the alpha2, alpha4, alpha5, alpha(v), and beta1 integrin subunits and aldolase (internal control). PCR products were analyzed by polyacrylamide gel electrophoresis (PAGE), confirmed via DNA sequencing, and quantified using computer-assisted densitometry. The expression of the integrin subunits was analyzed at the protein level using flow cytometry, as well as fluorescence and confocal laser microscopy. Cell morphology was evaluated using scanning electron microscopy (SEM). RESULTS: Our experiments demonstrated cellular expression of the alpha2, alpha4, alpha5, alpha(v), and beta1 integrin subunits at both mRNA and protein levels on all surfaces. In addition, the alpha4 and beta1 mRNA levels were significantly increased on smooth titanium relative to plastic surfaces (P <.05) with intermediate mRNA levels found on the rough titanium surfaces. The smooth titanium surfaces exhibited a flat monolayer of cells, while rough titanium surfaces showed cells orienting themselves along surface irregularities. CONCLUSIONS: These results demonstrate the presence of multiple integrin subunits in human gingival fibroblasts grown in contact with titanium implant surfaces and that titanium surface roughness alters cellular morphology but appears to have limited effects on integrin expression. This study provides insight into the complicated cellular and molecular events occurring at the implant surface that may be critical to optimizing the soft tissue interactions with the soft tissue-implant interface.

Cell Adhesion↗
PubMed1996

The expression of alpha v, alpha 5, beta 1, and beta 3 integrin chains on ejaculated human spermatozoa varies with their functional state.

Evidence has been presented suggesting the involvement of integrins and their ligands in mammalian fertilization. In this study we asked whether the alpha 5, alpha v, beta 1 and beta 3 integrin chains, which form receptors for fibronectin and vitronectin, are present on human spermatozoa. Fresh ejaculate spermatozoa and capacitated spermatozoa, before and after a calcium ionophore (A23187)-induced acrosome reaction, were either fixed and their reaction with anti-integrin monoclonal antibodies detected by immunoperoxidase staining or studied without fixation, using cytofluorimetric scanning. Expression of specific integrin chains varied with the functional state of spermatozoa. The alpha 5 chain was not detected on fresh living spermatozoa, but was present on capacitated spermatozoa, whether fixed or living. The pattern of beta 1 expression on living spermatozoa paralleled that of alpha 5. No further increase in the expression of either alpha 5 or beta 1 was observed following an ionophore-promoted acrosome reaction. In contrast, alpha v was detected on neither fresh, living ejaculate spermatozoa, nor following capacitation (< 10% reactive). The percentage of alpha v positive cells increased substantially following ionophore exposure. Expression of beta 3 was similar to alpha v, and the percentage of cells displaying beta 3 correlated with the proportion of spermatozoa that had undergone an acrosome reaction, following ionophore exposure. These results indicate that the expression of integrins on spermatozoa is dynamic, varying with their functional state and that integrin receptors for fibronectin (alpha 5 beta 1) become apparent on the spermatozoan surface during capacitation and vitronectin (alpha v beta 3) following the acrosome reaction.

Acetone↗
PubMed1995

Expression of a novel integrin beta 1 chain epitope and anti-beta 1 antibody-mediated enhancement of fibronectin binding are dependent on the stage of T cell differentiation.

Beta 1 integrins are a family of alpha beta heterodimers that serve as cell surface receptors for extracellular matrix proteins. We demonstrate that the anti-mouse integrin beta 1 chain mAb KMI6 selectively recognizes a beta 1 epitope that is constitutively expressed by certain immature thymocytes and is induced only slightly on mature thymocytes and peripheral T cells by activation with Con A. Because virtually all cells examined expressed beta 1 integrins on their surface, expression of the KMI6 epitope is T cell differentiation stage specific. Most CD3-4-8- thymocytes were KMI6+, with the lowest level of staining observed on the earliest CD44+IL-2R- cells within this subset. Expression was down-regulated during the CD3-4-8- to CD3-4-8+ transition, and lost by the CD4+8+ stage. Mature single positive thymocytes and resting peripheral T cells were also KMI6-. In contrast with the loss of the epitope before TCR expression by other thymocytes, most CD3+4-8- and certain CD8+ gamma delta TCR+ thymocytes were KMI6+ Addition of KMI6 to cell adhesion assays enhanced CD4-8- thymocyte, but not activated mature thymocyte or peripheral T cell, binding to fibronectin (via alpha 4 beta 1 and alpha 5 beta 1), whereas laminin binding (via alpha 6 beta 1) was unaffected. These properties distinguish the KMI6 epitope from other epitopes involved in beta 1 integrin activation in mice and other species. The unique selectivity of KMI6 recognition of beta 1 integrins, and its selective enhancement of ligand binding suggest that beta 1 integrin structure and factors that regulate beta 1 integrin binding are correlated with the stage of T cell differentiation.

Animals↗
PubMed2000

The effect of antigen stimulation on alpha(4), beta(1) and beta(7) chain integrin expression and function in CD4+ cells.

BACKGROUND: The alpha(4) integrin, as alpha(4)beta(1) (VLA-4) or alpha(4)beta(7), is critical for T cell migration and proliferation, although its functional modulation remains poorly understood. We hypothesized that increased receptor density, based on new receptor chain synthesis, was one such mechanism. We examined the surface receptor density of the alpha(4) and beta(1) chains on CD4+CD45RO+ cells, and the mRNA expression of these and the beta(7) chain in response to allergen and nonallergen antigen stimulation. METHODS: Flow-cytometric analyses for CD49d, CD29, and CD45RO were performed on T cell lines specific for timothy, tetanus, and Candida from atopic and nonatopic donors. RNA was extracted from cells sorted to select CD4+/CD49d-positive cells before and after stimulation. Equivalent amounts of cDNA for beta-actin, alpha(4), beta(1) and beta(7) were used in PCR, and the products were quantified using phosphoimaging. RESULTS: CD49d expression is heterogeneous on T cell lines and is upregulated by antigen stimulation on CD4+ T cells. The surface expression on CD4+CD45RO+ timothy allergen or tetanus toxoid T cell lines is at least double that found on CD45RO- cells. Antigen stimulation upregulated CD49d expression on the CD4+CD45RO+ subpopulation of both cell lines although it was not as significant as in the case of all CD4+ T cells. CD29 surface expression behaves similarly. Candida had no effect on CD49d or CD29. Messenger RNA expression for the alpha(4) chain (CD49d) is significantly upregulated 48 h following the addition of timothy or tetanus. beta(7) chain expression also rises significantly on both cell lines. beta(1) chain expression increases, but not significantly. CONCLUSIONS: The surface expression of the CD49d is heterogeneous and much higher on CD4+CD45RO+ cells than on CD4+RO- T cells. The CD49d integrin chain on CD4+ T cells is upregulated following antigen exposure. However, the CD4+CD45RO+ subpopulation is only partially responsible for this increase suggesting other T cells to have this receptor expression upregulated. CD29 expression behaves similarly. Messenger RNA expression increases coordinately for alpha(4), beta(7), and not significantly for beta(1) in these cells. These observations provide a potential mechanism for the selective accumulation of T cells at sites of inflammation, and suggest an important point of intervention for allergic and inflammatory disease.

Allergens↗
PubMed1993

Expression of CD18 (integrin beta 2 chain) correlates with prognosis in malignant B cell lymphomas.

Several studies have shown that cell cycle related parameters including DNA synthesis and activation antigen expression can predict patient survival in lymphoma patients. In this study of 69 malignant B cell lymphomas we have examined the cell surface expression of several cell interaction and activation molecules by flow cytometry. Expression of CD18 (integrin beta 2 chain) was found to correlate strongly with patient survival (median follow up 50 months) even when adjusting for other important prognostic factors (P = 0.0001). The percentage of cells positive for CDw75 proved important both as a single parameter and in the multivariate analysis. Histology, classified as low versus high grade malignancy, bulky versus not bulky disease and high versus low thymidine incorporation, was also found to correlate with prognosis in this study.

Antigens, CD↗