[The Concept of Immunogenic Cell Death in Antitumor Immunity]. / Význam imunogenní bunecné smrti v protinádorové imunite.

Cancer cell death can be immunogenic or nonimmunogenic depending on the initiating stimulus. The immunogenic characteristics of immunogenic cell death are mainly mediated by damage-associated molecular patterns represented by preapoptotic exposure of calreticulin and heat shock proteins (HSP70 and HSP90) from endoplasmic reticulum at the cell surface and active secretion of adenosintriphospate. Other damage-associated molecular patterns are produced in late stage apoptosis as high mobility group box 1 protein (HMGB1) into the extracellular milieu. Such signals operate on various receptors expressed by antigen presenting cells, mainly by population of dendritic cells, to stimulate the activation of antigen specific T-cell response. In this review, we describe the current known immunogenic cell death inducers and their potential to activate antitumor immune response.

[Active cellular immunotherapy of ovarian cancer using dendritic cells]. / Aktivní bunecná imunoterapie karcinomu ovaria pomocí dendritických bunek.

OBJECTIVE: Overview and comparison of current results of studies dealing with the development and application of anti-cancer vaccines based on dendritic cells in ovarian cancer. DESIGN: Review. SETTING: Department of Obstetrics and Gynaecology Charles University, Prague, 2nd Faculty of Medicine and University Hospital Motol, Department of Immunology 2nd Faculty of Medicine and University Hospital Motol. SUMMARY: Ovarian carcinoma (OVCA) is highly sensitive to chemotherapy; however despite this results from treatment are fairly unsatisfactory. Bearing this in mind, it is important to look for new ways to better understand the immunological mechanisms which could affect reactivation of the disease. It is likely that new knowledge in the field of the immunology of ovarian carcinoma could improve monitoring of the disease and help to ameliorate prognosis of the disease. One strategy in development is creation of anti-OVCA vaccines. Theese vaccines are made by the fusion of dendritic cell (DC) and tumor cells or its parts (NA, peptides). DC are bone-marrow derived leukocytes that are critical in the initiation of T cell mediated immunity. DC are fused to patient-derived ovarian carcinoma cells. The fusion cells induces cytotoxic T cell against autologous OVCA cells.

[K-ras mutational status and tumour-infiltrating lymphocytes in human colon cancer: state of the art and future perspectives]. / K-ras mutace a nádory infiltrující lymfocyty u karcinomu kolon, soucasnost a výhledy.

INTRODUCTION: Nowadays, the prognosis of newly diagnosed colorectal cancer patients relies mostly on the tumour-node-metastasis (TNM) classification which is also a determining criterion for the indication of adjuvant oncological treatment. Currently, new prognostic and predictive biomarkers are sought after in order to more precisely define prognosis and better predict the benefits of adjuvant treatment in colorectal cancer. Besides several molecular biomarkers, such as mutations in the proto-oncogene K-ras, analyses of tumour-infiltrating lymphocytes have shown promising prognostic value. The aim of the study is to examine the correlations between K-ras mutational status and tumour-infiltrating immune cells in colon cancer patients with respect to colon cancer recurrence. MATERIAL AND METHODS: Formalin-fixed paraffin-embedded specimens were obtained from 44 patients with surgically resected colon cancer (R0 resection) treated between 2004 and 2009. K-ras mutational status was detected using PCR amplification of exon 1 followed by direct sequencing and K-ras StripAssay. Tumour-infiltrating immune cells were detected by immunofluorescence staining using monoclonal antibodies against CD3, CD8, FoxP3, CD1a and DC-LAMP. RESULTS: All 44 patients in our cohort underwent radical resection of colon cancer. In 16 patients the tumour relapsed (36.4%). K-ras mutations were found in 45.5% (n=20) of the primary carcinomas: 65% in codon 12 and 35% in codon 13. Although codon 13 K-ras mutations were associated with disease relapse, they were present in both disease-free and relapsed patients. However, disease-free and relapsed patients differed markedly in their patterns of tumour-infiltrating immune cells. There was a trend towards decreased density of tumour-infiltrating lymphocytes within the group of relapsed patients. In addition, relapsed patients with codon 13 mutations had markedly lower levels of tumour-infiltrating mature DC-LAMP+ dendritic cells and higher frequency of CD1a+ cells compared to disease-free patients. CONCLUSION: Colon cancer patients with low levels of tumour-infiltrating lymphocytes, a high CD1a+/DC-LAMP+ tumour-infiltrating DC ratio and a K-ras mutation in codon 13 are at a high risk of disease recurrence.

Serum immunoglobulin free light chains in severe forms of atopic dermatitis.

An increase in immunoglobulin free light chains (FLC) was recently described in several pathological conditions, including asthma. FLC pathology is classically associated with monoclonal gammopathies. Its association with allergic disorders is surprising and unexplained. We therefore tested a cohort of children with severe atopic dermatitis (SCORAD 50-80) to determine the serum levels of free kappa and lambda chains, and correlated the results with clinical status and relevant laboratory markers. Seventy-three patients with severe forms of AD, all children from 3 months to 3 years of age and ninety healthy age-matched controls were included in the study. Light chains in sera were tested using the Freelite assay (Binding Site, Birmingham, UK). There were highly significant differences in both kappa (mean: 7.05 and 3.22 mg/l) and lambda (mean: 10.99 and 9.8 mg/l) serum levels between patients and controls, respectively (P < 0.0001). The kappa/lambda ratio in patients with allergy (mean: 0.64) was significantly higher than in controls (0.33) (P < 0.0001). We further observed significantly increased levels of FLC and their ratio in the group of patients with severe forms of AD in comparison to the group of patients with a resting stage of the disease or healthy controls (P < 0.05 and P < 0.0001, respectively). On the other hand, we could not confirm any association of FLC levels with age or total IgE levels. In conclusion, an increase in FLC reflects disease activity in children with severe atopic dermatitis. FLC might thus represent an additional diagnostic marker independent of total IgE levels.

Assessment of lymphocyte proliferation: CFSE kills dividing cells and modulates expression of activation markers.

The measurement of cell proliferation after mitogenic stimulation is an important parameter used in diagnosis of immunodeficiencies in clinical laboratory as well as in various fields of lymphocyte research. Recent methods try to overcome the radioactive assay using tritiated thymidine ((3)H) by flow-cytometric methods using different fluorochromes such as CFSE or even to substitute these direct methods by tracing the expression of cell-membrane activation markers associated with various steps of proliferation cycle. In our study we compared the (3)H assay with CFSE-staining method and expression of activation markers (CD69, HLA-DR, CD25, CD27, CD71, CD152, CD134 and CD195) on a sample of 128 consecutive patients and healthy controls evaluated in clinical laboratory. We also tested various concentrations of CFSE and its impact on proliferation activity and expression of activation markers. We found that CFSE in concentration from 37nM to 10microM decreases the proliferative capacity (expressed in cpm (3)H assay) due to the decreased viability of proliferating cells (measured as 7-AAD+) in concentration-dependent manner. Moreover, CFSE substantially modulates the expression of activation molecules (decreasing CD69, HLA-DR, CD25 the majority of examinated molecules). We found a good correlation between CFSE-staining method with (3)H assay, if CFSE low population is gated on CD3+ population (correlation coefficient 0.801), but only in samples with stimulation index (SI) higher then 25. In poorly proliferating samples (SI25) no correlation was found due to several false positive results in CFSE test. Statistically significant correlation between proliferation assessed as (3)H-thymidine incorporation and expression of activation markers was found in the case of CD25, CD27, CD38, CD152, CD71, still only in samples with higher proliferation activity (SI>25). No correlation was found with CD134, CD195, HLA-DR and CD69. We conclude that standard assay with (3)H-thymidine incorporation is unreplaceable assay in diagnosis of severe cellular immunodeficiencies as CFSE assay have high proportion of false positive results. Researchers tracing cell-membrane bound molecules on dividing cells stained by CFSE must take into account that CFSE may substantially modulate the expression of these markers and decrease the viability of stained cells.

Prolonged impairment of polymorphonuclear cells functions in one infant with transient zinc deficiency: a case report.

BACKGROUND: Zinc is an essential trace element for the immune system. The zinc deficiency diminishes antibody- and cell-mediated responses in man. Lymphopenia and thymic atrophy are usually the early hallmarks of zinc deficiency. Surprisingly, only scarce data are available about polymorphonuclear cells (PMNs) functions in infants with zinc deficiency. We present the results of immunological analyses in one infant with transient zinc deficiency due to decreased zinc concentration in mother milk resulting in severe lactogenic acrodermatitis enteropathica. MATERIAL/METHODS: Nine repeated examination of oxidative burst of PMNs and immunoglobulin levels using nitroblue tetrazolium dye test, chemiluminescence, flow cytometry and nephelometry were performed in the infant with severe zinc deficiency during 28 months period. RESULTS: The unusual prolonged but transient impairment of PMNs respiratory burst accompanied with hypogammaglobulinaemia developed since the age of 2.5 months. Dramatic improvement of the skin was observed within days with total resolution of skin lesions on the 9th day of zinc therapy, but decreased PMNs respiratory burst persisted until the age of 23 months. CONCLUSIONS: We conclude that zinc deficiency may lead to prolonged impairment of polymorphonuclear cells functions and hypogammaglobulinaemia.

[Prevalence of hepatitis G virus infection (HGV) in intravenous immunoglobulin recipients in the Czech Republic]. / Výskyt infekce virem hepatitidy G (HGV) u pacientu lécených intravenózními imunoglobuliny v Ceské republice.

The prevalence of hepatitis G virus (HGV) in the serum of intravenous immunoglobulin (IVIG) recipients was studied and risk related to HGV positivity was considered. Although its pathogenicity is unclear, HGV is likely to cause liver disease or lymphoproliferation. Twenty (23%) of 86 tested MG patients were HGV RNA positive. Of the HGV positive patients, three (15%) showed mild elevation of liver enzymes and one (5%) was diagnosed with chronic lymphatic leukaemia prior to the institution of MG replacement. It can be concluded that the HGV prevalence among IVIG recipients is high but is not associated with signs of either liver disease or lymphoproliferation.

[Auto- and alloreactivity of T lymphocytes in myelodysplastic syndrome]. / Auto- a aloreaktivita T lymfocytu u myelodysplastického syndromu.

BACKGROUND: Successful therapy with ATG and cyclosporine A in some myelodysplastic syndrome (MDS) patients led us to study the existence of T cells attacking autologous hemopoietic cells. In our study, we attempted to give the direct prove of autoreactive T cells in MDS (autoreactivity analysis). Simultaneously, we analysed the capacity of MDS patients to respond to allogeneic cells from unrelated individuals (alloreactivity analysis). METHODS AND RESULTS: Autoreactive lymphocytes directed against own bone marrow mononuclear cells were analysed using the modification of cell mediated cytotoxic reaction. With one exception we did not confirm the presence of autoreactive T cells among 10 patients examined. Analysis of alloreactivity was performed by means of standard cell mediated cytotoxic reaction and mixed lymphocyte reaction. Surprisingly, the cytotoxic response to allogeneic cells was negative in 11 MDS patients from 16 analysed. When comparing refractory anaemia (RA) and refractory anaemia with ring sideroblasts (RARS) patients, the proportion of negative results was higher in RA (78 %) than in RARS (40 %). In mixed lymphocyte reaction, the response of MDS cells to allogeneic cells of unrelated individual was positive in all tested patients. The preliminary testing of TNF and IFNgamma secretion examined in supernatants of effector cells showed impaired levels of both cytokines in RA and normal levels in RARS in accordance with the findings achieved in alloreactivity analysis. CONCLUSIONS: Autoreactive T cells were not found in MDS patients using our experimental arrangement. Analysis of alloreactivity showed the defect in effector--cytotoxic--phase of cell mediated cytotoxic reaction in the majority of MDS patients. The initial phase of this reaction represented in vitro by mixed lymphocyte reaction gave normal results. The possible reasons of disturbed alloreactivity and its relevance to immunity in MDS are commented in discussion.

Effects of human plasma proteins on maturation of monocyte-derived dendritic cells.

Dendritic cells (DC) are a promising tool for vaccine therapy due to their unique properties as antigen presenting cells and their ability to prime naïve T cells. Increasing evidence suggests that maturation stage of DC critically influences the fate of the immune response. Generation of monocyte-derived DC for clinically applicable immunotherapy requires the use of well-defined components and stringent culture conditions. An alternative strategy is to use human autologous serum. However, its constituents are not stable and reflect the inflammatory condition of the donor. In order to investigate whether DC properties are influenced by proteins present in the plasma, we matured human monocyte-derived DC with four main plasma components: fibrinogen, fibronectin, plasminogen or C-reactive protein. These purified proteins were added at various concentrations on day 6 after the initial differentiation induced by IL-4 and GM-CSF. The maturation was assessed by phenotyping of maturation-associated marker (CD83) and co-stimulatory molecule CD86 as well as IL-12 production. Functional properties of DC were assessed by endocytic activity and mixed leukocyte culture. Our results indicate that fibrinogen had DC-maturation effect comparable to poly-I:C, TNF-alpha and PGE(2) as a positive control, but it failed to induce IL-12 production. The other plasma proteins had no effect on DC maturation. CRP at high concentration had rather inhibitory effect on DC induced lymphocyte function. We conclude that none of the tested plasma components and acute phase proteins sufficiently induce fully competent mature DC. This finding is important for the preparation of human DC-based vaccines supplemented by autologous sera.

Aberrant expression of KOR-SA3544 antigen in childhood acute lymphoblastic leukemia predicts TEL-AML1 negativity. The Pediatric Hematology Working Group in the Czech Republic.

The antigen KOR-SA3544 is physiologically expressed exclusively on granulocytes. Aberrant expression of KOR-SA3544 has been invariably found in BCR/ABL-positive acute lymphoblastic leukemia (ALL) and in some BCR/ABL-negative ALL. In an interim analysis of a prospective clinical and cytometric study data of 73 children with newly diagnosed or relapsed ALL with and without TEL/AML1 fusion are presented. KOR-SA3544 expression over 3% was detected in the majority of TEL/AML1-negative patients with newly diagnosed common or preB ALL (19 of 31) and not in TEL/AML1-positive patients (0 of 18, P < 0.0001). The level of expression of KOR-SA3544 was 0.02-90% (median 6.0%) and 0.03-2.4% (median 0.23%) in TEL/AML1-negative and TEL/AML1-positive patients, respectively. All five newly diagnosed patients with DNA index > or =1.16 and <1.6 exhibited high levels of KOR-SA3544 expression. Membrane expression of CD79a was found to correlate with TEL/AML1 negativity, although less significantly than KOR-SA3544 (P = 0.03). Furthermore, our data confirm that TEL/AML1 positivity correlates with non-hyperdiploidy and low presenting age. In conclusion, KOR-SA3544 correlated strongly with TEL/AML1 negativity, it was a better predictor of TEL/AML1 status than other factors tested and was found at high levels in hyperdiploidy. In combination with age, KOR-SA3544 predicted TEL/AML1 status in 86% newly diagnosed preB/cALL patients.

Coexpression of binding sites for A(B) histo-blood group trisaccharides with galectin-3 and Lag antigen in human Langerhans cells.

Galectin-3 is an immunomodulatory protein with binding capacity for various glycoconjugates including IgE. It has been shown to be produced by epidermal keratinocytes and is present on the surfaces of skin Langerhans cells (LC). Therefore, it may have a role in the pathogenesis of various skin diseases, such as atopic dermatitis. To study the expression of galectin-3 in LC, we used, in addition to specific antibodies, a panel of synthetic, carrier-immobilized, specific oligosaccharides of the A- and B-histo-blood group, which are recognized by this lectin. In the mean time, Birbeck granules were visualized with an anti-Lag antibody. The double labeling experiments showed a remarkable colocalization of signals for Lag antigen (Birbeck granules) and galectin-3, as well as the binding sites for A- and B-histo-blood group trisaccharides. The specificity of the oligosaccharide binding was demonstrated by the lack of binding by Le(c), Le(d) (H blood group antigen), and sLe(x), which are not recognized by galectin-3. These results suggest that galectin-3 is present in Birbeck granules, where it retains reactivity for its glycoligands.

[Glucocorticoids and their effect on dendritic cell function]. / Glukokortikoidy a jejich vliv na funkci dendritických bunek.

BACKGROUND: Dendritic cells represent the most effective antigen presenting cells and they are the only cell type capable of initiating the primary immune response. They use several sets of germ-line encoded receptors to differentiate between self and non-self and to detect the presence of danger signals. Danger signals are mainly represented by microbial pathogens but it can be also a necrotic or malignant cell. At various stages of their lifecycle dendritic cells play a key role in maintaining the peripheral tolerance towards self-antigens and in the initiation of an effective immune response. Glucocorticoids have been widely used in the treatment of autoimmune or inflammatory disorders and their immunosuppressive effect has been mainly attributed to the inhibition of lymphocytes functions. METHODS AND RESULTS: In this study, we discuss the effects of glucocorticoids on in vitro generated myeloid dendritic cells and on peripheral blood myeloid and plasmacytoid dendritic cells subsets. CONCLUSIONS: Experimental results point to the profound suppressive effect of glucocorticoids on the antigen presenting functions of dendritic cells and to contribute to better understanding of glucocorticoids-mediated immunosuppressive effect.

Reduced phagocytic activity of polymorphonuclear leukocytes in alpha(1,3) fucosyltransferase VII-deficient mice.

Deficiencies in adhesion molecules or their counter-receptors in humans may have severe consequences as exemplified by leukocyte adhesion deficiency (LAD) I or II syndromes. Because such diseases occur with great rarity, animal models are valuable for studying the role of particular adhesion molecules and their natural ligands in immunity. We studied selected immune parameters and general health in mice with a defect in the sialyl-Lewis X antigen (selectin ligand) caused by disruption of the gene encoding alpha(1,3)fucosyltransferase VII (Fuc-TVII). Leukocytes from Fuc-TVII -/- and control mice were tested for adherence to cellophane membranes or polymer particles in vivo and phagocytic activity in vitro. While no difference in adherence was found, the number of neutrophil granulocytes in exudate induced by intraperitoneal injection of polymer beads was reduced in knock-out mice. Moreover, the phagocytic activity in Fuc-TVII -/- mice was significantly reduced. These animals have splenomegaly due to increased hematopoiesis and reduced weight but do not exhibit clinical signs of immunodeficiency. In conclusion, the lack of Fuc-TVII activity leads to several morphological and functional abnormalities without an impact on survival rate.

Effect of phagocytosis of pHEMA particles and of heat-killed Candida albicans on expression of carbohydrate-binding sites such as endogenous lectins in phagocytes.

Phagocytosis of particles is an integral part of the defence system. Besides clearing the environment of foreign material this mechanism may affect the expression of physiologically relevant epitopes such as carbohydrate-binding sites, e.g. lectins. To determine the effect of particle design on the expression of such determinants in human monocytes and peritoneal macrophages either in suspension or after adherence, the binding of labelled (neo)glycoproteins was comparatively studied after exposure to poly (2-hydroxyethyl methacrylate) particles and heat-inactivated Candida albicans cells. A stimulatory effect of phagocytosis on extent of expression of binding sites for (neo)glycoproteins in phagocytic cells was observed. The levels of responsiveness varied according to the type of particle, adherence of the cell adding a further regulatory parameter. These results support the notion of a potential influence of the chemical structure and/or the form of an engulfed particle on phagocyte differentiation.

Effect of chemical structure of hydrogels on the adhesion and phenotypic characteristics of human monocytes such as expression of galectins and other carbohydrate-binding sites.

The reactivity of diverse immune aspects to the presence of synthetic polymers represents one of the most important aspects of implantable device biocompatibility. In this report, we show the effect of the chemical structure of a synthetic polymer support on monocyte adhesion and selected phenotypic characteristics in vitro as a model for the initial steps of non-self-recognition of an implant. The extent of monocyte adhesion was significantly influenced by the support chemistry. The highest level of monocyte adhesion was observed on a surface copolymer of 2-hydroxyethyl methacrylate with dimethyl aminoethyl methacrylate relative to results of experiments in which poly(2-hydroxyethyl methacrylate) or the copolymer of 2-hydroxyethyl methacrylate with the sodium salt of methacrylic acid was used. Cell adhesion to the polymers tested and to glass was accompanied by enhanced expression of the carbohydrate-binding sites tested for asialoglycoprotein beta-galactosides such as galectins, beta-N-acetylgalactosamine, alpha-mannoside, specific lectin for heparin as well as the lymphokine-macrophage migration inhibitory factor in the monocytes tested. These results suggest the importance of monocyte adhesion to the biomaterial surface for their development into macrophages and further non-self-recognition of the implanted device.

Successful HLA-identical sibling cord blood transplantation in a 6-year-old boy with leukocyte adhesion deficiency syndrome.

A 6-year-old boy with the severe form of the leukocyte adhesion deficiency syndrome (LAD) received a transplant of cord blood (CBT) from his HLA-identical brother. The donor was proved healthy by successful prenatal diagnosis. CBT was performed after conditioning with etoposide, busulfan and cyclophosphamide. After hematopoietic recovery complete chimerism was proved as well as the normal expression of CD11x/CD18 complex on circulating leukocytes. The only post-transplant complication was a mild pneumonitis resolving on the corticosteroid therapy. Thirteen months after CBT the boy is in good health and shows no signs of immunodeficiency. As far as we know this is the first report of successful CBT in a patient with LAD syndrome.

Primary Sjögren's syndrome in children and adolescents: proposal for diagnostic criteria.

OBJECTIVE: Primary Sjögren's syndrome (pSS) in childhood is a rare disease. Diagnostic criteria are available for adult patients only. In order to establish diagnostic criteria for juvenile pSS an analysis of 7 girls and one boy suffering from pSS with early onset is reported. Due to the rarity of the disease, data on patients with pSS reported in the literature are included in the proposal for modified diagnostic criteria. METHODS: The diagnosis of pSS was established according to the criteria for adulthood pSS, duly modified, which include clinical symptoms and laboratory immunological evaluation. RESULTS: The average age of our patients at clinical onset was 13.5 years (range: 10-17 yrs.). Clinical signs included systemic (fever, fatigue) as well as local (parotitis, vulvovaginitis, conjunctivitis) symptoms. Paralysis due to hypokalemia linked to renal tubular acidosis and central nervous system (CNS) involvement was seen in one patient. Asymptomatic renal tubular acidosis was diagnosed in another 2 patients. Autoimmune hepatitis was present in 2 patients. All patients had laboratory abnormalities: hyperimmunoglobulinemia IgG, high titers of antinuclear antibodies (anti-SS-A and/or anti-SS-B) and elevated serum amylases. Sicca syndrome was never seen during childhood, although it developed later in 3 patients, after 7 to 10 years of follow-up. CONCLUSIONS: It has been stressed that the classical diagnostic criteria for adult Sjögren's syndrome, especially sicca syndrome, are not applicable to a pediatric onset of the disease. On the other hand, the presence of typical laboratory abnormalities can allow the diagnosis of these patients in the early stages. Both laboratory and clinical symptoms typical for childhood are included in our proposal for diagnostic criteria applicable to juvenile pSS. Life-threatening conditions such as hypokalemic paralysis, CNS involvement and hepatitis may also occur in children. Sicca syndrome tends to develop much later in pediatric patients.

Detection of alpha(beta)-N-acetyl-D-galactosamine-binding sites in kidney--relation to Henoch-Schönlein-associated IgA nephropathy.

Henoch-Schönlein purpura is the most common vasculitis of childhood, accompanied by the deposition of IgA1 immunoglobulins into the glomerular mesangium. The actual molecular mechanism of IgA deposition is not clear, but the altered glycosylation of O-linked oligosaccharides of the hinge region of IgA1 is generally considered as the crucial etiopathogenic factor. The oligosaccharides of this glycoprotein from healthy persons are principally of mucin-type Galbeta1,3GalNAcalpha-O-glycan core structure, frequently sialylated. The patient's IgA hinge region saccharide is an incomplete GalNAcalpha-O-glycan only. This study investigates the presence of binding sites for alpha-GalNAc and beta-GalNAc in frozen sections of kidney with and without nephropathy prompted by the possibility for a lectin mechanism of IgA deposition to mesangium. Neoglycoproteins prepared as conjugates with derivatized alpha- or beta-GalNAc moieties as histochemically crucial ligands and biotinylated bovine serum albumin as a carrier were employed for this purpose. The result of the experiments demonstrated expression of specific and accessible binding sites for both alpha- and beta-GalNAc in tubules but not in glomeruli of kidney samples both with and without nephropathy. These findings imply no involvement of a lectin mechanism of IgA1 binding to mesangium, unless a temporary alteration of accessibility of binding sites for probes in glomeruli occurs or the linkage region beyond the monosaccharide is pivotal for a receptor whose binding site may accommodate a peptide epitope in addition to the O-linked alpha-GalNAc residue.

Human epidermal Langerhans cells are selectively recognized by galectin-3 but not by galectin-1.

Langerhans cells are dendritic antigen-presenting cells residing predominantly in the epidermis. Since endogenous galactoside-binding lectins with the jelly-roll motif (galectins) are known to trigger cellular responses, including mediator release, we investigated by lectin histochemistry the cells' capacity to bind two common members of this family, i.e. galectin-1 and -3. Actually, surrounding keratinocytes express a high level of galectin-3, and these cells can be considered as donors of this lectin to Langerhans cells. Employing biotinylated galectin-1 and -3, and concomitantly an antibody against CD1a as a second marker, to visualize the position of Langerhans cells in the human epidermis, the expression of galectin-3-reactive glycoligands in contrast to the lack of binding of galectin-1 was observed. Although the functional consequences of this selectivity are unclear, these results reveal an example for differential cellular reactivity towards two related endogenous lectins.