Recommendations of the Spanish brachytherapy group (GEB) of Spanish Society of Radiation Oncology (SEOR) and the Spanish Society of Medical Physics (SEFM) for high-dose rate (HDR) non melanoma skin cancer brachytherapy

Clinical indications of brachytherapy in non-melanoma skin cancers, description of applicators and dosimetry recommendations are described based on the literature review, clinical practice and experience of Spanish Group of Brachytherapy and Spanish Society of Medical Physics reported in the XIV Annual Consensus Meeting on Non Melanoma Skin Cancer Brachytherapy held in Benidorm, Alicante (Spain) on October 21st, 2016. All the recommendations for which consensus was achieved are highlighted in blue. Regular and small surfaces may be treated with Leipzig, Valencia, flap applicators or electronic brachytherapy (EBT). For irregular surfaces, customized molds or interstitial implants should be employed. The dose is prescribed at a maximum depth of 3-4 mm of the clinical target volume/planning target volume (CTV/PTV) in all cases except in flaps or molds in which 5 mm is appropriate. Interstitial brachytherapy should be used for CTV/PTV >5 mm. Different total doses and fraction sizes are used with very similar clinical and toxicity results. Hypofractionation is very useful twice or 3 times a week, being comfortable for patients and practical for Radiotherapy Departments. In interstitial brachytherapy 2 fractions twice a day are applied.

Antibody-mediated activation of a defective beta-D-galactosidase. II. Immunological relationship between the normal and the defective enzyme

Two closely related protein antigens were used to study immunogenic competition. Namely, normal β-D-galactosidase of Escherichia coli (Z) and a genetically defective β-D-galactosidase (AMEF) which seems to differ from the normal in one amino acid substitution. A unique characteristic of this pair of antigens is that, although they are indistinguishable in precipitation and absorption tests with antibodies, the enzymatic activity of AMEF is specifically increased several-hundredfold in the presence of antibodies directed against Z. The following results show that Z and AMEF also differ in their immunogenic ability: (a) antibodies directed against Z activated AMEF; antibodies directed against AMEF did not activate, but competed specifically with activating antibodies. (b) Animals immunized with AMEF failed to produce activating antibodies when they were subsequently challenged with Z, although the presence of some cells primed to produce activating antibodies could be demonstrated by adoptive transfer. (c) Animals preimmunized with Z were stimulated in their production of activating antibodies by AMEF challenge, although not as efficiently as with Z. A model explaining these observations by competition for the immunogenic site among antigen-sensitive cells carrying cross-reacting receptors is presented.

European doctorate in biotechnology: Added value for european academia and industry

It has long been recognized that educational programs and degrees are not equivalent across Europe. Add to this the fact that Europe consists of many different cultures and languages, then it is not surprising that the free circulation of scientists and their job market in the European Union is severely restricted. This is one of several debated causes for the crisis in European biotechnology, which is in danger of succumbing to the competition of North America, Japan, and some of the developing countries. The Universities (even those tradition-ridden), the European University Association, and the European Commission are aware of the danger and plans are in preparation for sweeping organizational and cultural changes. The problem is how long will it take and how long can we afford to wait? A number of biotechnologists and scientists from several institutions and many countries decided, instead of waiting, to make a preliminary move in the right direction. With the help of the European Commission and using European Molecular Biology Organization, European Federation of Biotechnology, and the European University Rectors as references, the European Association for Higher Education in Biotechnology was founded in 1995 by representatives of universities and research institutes. It awards the additional title of European Doctor to PhD graduates showing excellence in biotechnology and/or related Life Science subjects and who are willing to fulfil a program of studies that is both international and interdisciplinary. The present article reports on the first 9 years of this adventure.

A systematic approach to vaccine complexity using an automaton model of the cellular and humoral immune system. I. Viral characteristics and polarized responses

A modern approach to vaccination faces the compound complexity of microorganism behavior and immune response triggering and regulation. Since computational modeling can yield useful guidelines for biological experimentation, we have used IMMSIM(3), a cellular automaton model for simulating humoral- and cell-mediated responses, to explore a wide range of virus-host relations. Sixty-four virtual viruses were generated by an assortment of speed of growth, infectivity level and lethal load. The outcome of the infections, as influenced by the immune response and the bolstering of cures, obtained by vaccine presensitization are illustrated in this first article. The results of the in machina experiments allow us to relate the success rate of responses to certain combinations of viral parameters and by freezing one or the other branch, and to determine that some viruses are more susceptible to humoral, and others to cellular responses, depending either on single parameters or combinations thereof. This finding allows prediction of which infection may be susceptible to polarized ((Th)(1)>Th(2) and Th(1)<Th(2)) responses and will eventually help designing vaccines whose action relies on antagonizing both the specificity and the behavior of the invader. A second, not lesser, result of this study is the finding that humoral and cellular responses, while cooperating, towards the cure of the infected body, also show significant patterns of competition and mutual thwarting.

Affinity maturation and hypermutation in a simulation of the humoral immune response

By experimenting with a cellular automaton model of the immune system, we have reproduced affinity maturation of the antibody response, a somatic adaptation to a changing environment. The simulation allowed the isolation of a number of variables, e.g. the fraction of repertoire available, the magnitude of the change in affinity with mutation, the mutation frequency and its focus on the complementarity-determining regions (CDR) of the antibody. Multiple series of immunizations were run in machina where the contribution of each variable was evaluated against the maturation observed. We found that hypermutation is not necessary for affinity maturation if the repertoire of B cell specificities is sufficiently complete, but is essential when the B cell diversity is limited (which happens to be the case in vivo), as it fills the holes in the repertoire and allows selection by antigen. Maturation also depends on the magnitude of the change in affinity with mutation, and we supply some necessary limits on this parameter. For mutations confined to the CDR, the most efficient maturation occurs at mutation rates of 0.2 per paratope and per cell division. When mutations also affect the framework regions, the peak of the most effective CDR mutation rate moves progressively to lower values. A most sensitive parameter is the speed of maturation, which reflects the rate of expansion of mutated clones. Comparing it with biological observations can help to discriminate between alternative hypotheses on the phenomena of hypermutation and affinity.

Autoantibodies to CD4 in HIV type 1-exposed seronegative individuals

The aim of this study was to investigate the presence and the fine specificity of anti-CD4 autoantibodies in seronegative subjects sexually exposed to HIV-1. Anti-CD4 autoantibodies were previously detected in a fraction of HIV-1-seropositive individuals. Whole sera, purified IgG fractions, and supernatants of EBV-transformed lymphoblastoid cell lines were analyzed by means of ELISA, Western blot, and by competition assays using monoclonal antibodies with known fine specificities. Anti-CD4 antibodies were found in 6 of 18 individuals exposed to HIV-1 infection and who have been persistently seronegative. These antibodies inhibited HIV-1-driven syncytium formation, did not interfere with the CD4-gp120 interaction, and competed for CD4 binding with two of three anti-CD4 monoclonals with known fine specificities. Moreover, autoantibodies with the same fine specificities were found in the supernatants of oligoclonal EBV-transformed B cell lines derived from these individuals. At variance, in the HIV-1-positive patients included in our study, the anti-CD4 antibody response was directed to a broader panel of epitopes, including those involved in CD4-gp120 interactions. In conclusion, anti-CD4 antibodies specific for defined epitopes of the CD4 molecule are generated in the course of an early immune response to HIV-1 antigens in the absence of other signs of infection, as they can be detected by conventional methods. These autoantibodies may play a protective role either alone or in association with other cellular and humoral factors.

Modelling thymic functions in a cellular automaton

Along the lines developed by Celada and Seiden, for simulating an immune system by means of cellular automata, we have constructed a 'thymus' where T cells undergo positive and negative selection. The populations thus 'matured' have been analyzed and their performance has been tested in machina. The key feature of this thymus is to allow chance meeting and possible interaction between newly born T cells and antigen presenting cells. The latter represent both the epithelial and the dendritic cells of the biological organ and are equipped with MHC molecules that can accommodate selected self peptides. All possible specificities are represented among the virgin T cells entering the thymus, but this diversity is drastically reduced by the time they exit as mature elements. In the model organ the fate of T cells, i.e. whether they will undergo proliferation or apoptosis, is governed by their capacity to recognize MHCs and the affinity of this interaction. Crucial parameters turn out to be the concentration of presenting cells, the number of types of MHC per cell, the 'size of self' in terms of the number of different peptides and their prevalence. According to the results, events in the automaton can realize unforeseen cooperations and competitions among receptors, depending upon the interaction order and frequency, and ultimately determine the rescue or the killing of thymocytes. Thus the making of the mature T repertoire has a random component and cannot be completely predicted.

A monoclonal antibody to the gp120-CD4 complex has differential effect on HIV-induced syncytium formation and viral infectivity

A murine monoclonal antibody (MAb F-91-55) raised against the complex of soluble CD4 and human immunodeficiency virus type 1 (HIV-1) gp120 had previously been found to inhibit syncytium formation without inhibiting the interaction of CD4 with gp120, and its binding site was localized within the first two domains (D1/D2) of CD4. We investigated whether this antibody inhibited the infectivity of HIV-1 in the CD4+ T cell lines A3.01, Sup-T1 and H9. We also examined the effect of the antibody on syncytium formation between these cells and chronically infected H9 cells. Syncytium formation was found to depend critically on the incubation medium used. The effect of the MAb on HIV-1 infectivity was very limited with A3.01 and Sup-T1 cells, although it inhibited syncytium formation between A3.01 or Sup-T1 and chronically infected H9 cells. In contrast, the MAb inhibited significantly the infectivity of HIV-1 in H9 cells, but it also inhibited syncytium formation between H9 and chronically infected H9 cells to a greater extent than in the case of the other cell lines. Our results indicate that cellular systems used for syncytium assays differ in their susceptibility to inhibitory antibodies. In the A3.01 and Sup-T1 cell systems, the differences in the ability of the MAb to block viral entry or syncytium formation raise the possibility that the mechanisms of interaction of gp120/gp41 with cell membrane CD4 may be different in cell-cell and virus-cell membrane fusion.

Non-covalent complexes of HIV gp120 with CD4 and/or mAbs enhance activation of gp120-specific T clones and provide intermolecular help for anti-CD4 antibody production

The 'dangerous liaison' between CD4 and gp120 that offers the first entry opportunity to HIV may also provoke perturbations of the immune control of the host with far-reaching immunopathological consequences. We wondered whether a mechanism of intermolecular help (T help across the gap of a non-covalent bond, in contrast to the intramolecular help of carrier to hapten) could break self-tolerance and be the cause of the frequent anti-CD4 autoantibodies found in AIDS patients. To determine whether this hypothesis deserves further testing, we designed a series of in vitro and in vivo experiments of increasing complexity, focused on the presentation of gp120 to specific T cells by antigen presenting cells (APC) exposed to the envelope protein in the form of non-covalent complexes. Bi-molecular complexes were constructed by allowing gp120 or gp160 to bind specific human mAbs. Tri-molecular complexes were constructed by introducing CD4 as an intermediate ligand between gp120 and mouse mAbs specific for CD4. In all cases the use of complexes did enhance the immunogenic capacity of substimulatory doses of gp120 or gp160 by facilitating uptake by APC via Fc receptor and consequent presentation to specific human T cell clones. Finally, help for the production in vivo of anti-CD4 antibodies was obtained from T lymphocytes specific for gp120 when CD4-primed memory B cells were pulsed with CD4 complexed with gp120, thus demonstrating in the mouse the entire cycle of intermolecular help via non-covalent interaction, and setting the stage for future experiments on self-tolerance breakage in a human molecular context.

A model for simulating cognate recognition and response in the immune system

We have constructed a model of the immune system that focuses on the clonotypic cell types and their interactions with other cells, and with antigens and antibodies. We carry out simulations of the humoral immune system based on a generalized cellular automaton implementation of the model. We propose using computer simulation as a tool for doing experiments in machine, in the computer, as an adjunct to the usual in vivo and in vitro techniques. These experiments would not be intended to replace the usual biological experiments since, in the foreseeable future, a complete enough computer model capable of reliably simulating the whole immune would not be possible. However a model simulating areas of interest could be used for extensively testing ideas to help in the design of the critical biological experiments. Our present model concentrates on the cellular interactions and is quite adept at testing the importance and effects of cellular interactions with other cells, antigens and antibodies. The implementation is quite general and unrestricted allowing most other immune system components to be added with relative ease when desired.

Guidelines for the PhD degree in immunology. International Union of Immunological Societies Education Committee

The International Union of Immunological Societies, recognizing the need for internationally acceptable standards for the PhD degree in immunology, commissioned the IUIS Education Committee to prepare recommendations on the subject. This document, the result of a two-year study of PhD programs in many countries, presents these recommendations.

Kinetic immunodominance: functionally competing antibodies against exposed and cryptic epitopes of Escherichia coli beta-galactosidase are produced in time sequence

The murine antibody response to Escherichia coli beta-galactosidase (GZ) was analyzed in vivo and in vitro by focusing on two families of antibodies that exert distinct conformational/functional activity on the antigen. Activating antibodies--defined by their capacity to increase the enzymatic activity of defective GZ produced by mutant strains of E. coli--are detected early after secondary challenge. Inhibiting antibodies, which interfere with antibody-mediated enzyme activation, appear later and cause the abrupt fall of activating titer, a scenario suggesting either idiotype/anti-idiotype interaction or opposite pulsions exerted on the antigen molecule. Supporting the latter mechanism, the confrontation of mAbs of the two families produced classical competitive inhibition curves when the readout was enzyme activation, although they recognize two different epitopes of the same molecule: the activating mAb a quaternary conformation-dependent site of wild-type GZ, the inhibiting mAb a sequential determinant exposed only in denatured or in defective enzyme. The different timing of generation of these antibodies during the response may depend on a processing step necessary for unfolding of native antigen and consequent display of certain cryptic epitopes before they can trigger specific B cells. A picture emerges where the response to the various epitopes of a complex antigen is sequentially connected and where the uptake by antigen-presenting cells of antigen complexed with antibodies specific for the exposed epitopes may favor revelation of the cryptic ones.

Inhibitory activity of HIV envelope gp120 dominates over its antigenicity for human T cells

HIV-1 envelope glycoprotein (gp120), as a CD4-binding reactant, has been shown to inhibit in its native form human T cell responses to several antigens. Here we show that gp120 in soluble form also inhibits activation of a specific human T cell line that responds to gp120-pulsed autologous antigen-presenting cells. In addition the inhibitory property of gp120 for antigen-driven T cell proliferation depends upon its ability to bind CD4 and is lost when CD4-binding capacity is abolished by denaturation, or blocked by complexing with soluble CD4 or with polyclonal antibodies. In contrast, antigenicity of denatured or complexed gp120 for specific human T cells is preserved. Similar effects are also observed with another CD4-binding reactant (i.e. anti-Leu 3a MoAb), which stimulates and/or inhibits human T cells specific for mouse immunoglobulins depending on native or denatured conformation.

A computer model of cellular interactions in the immune system

The power of modern computers allows the modeling and simulation of complex biological systems. The last decade has seen the emergence of a growing number of simulations of the immune system. In this article, Franco Celada and Philip Seiden present a model that, they suggest, is rich enough to allow computer experiments to be used as practical adjuncts to the usual biological experiments, at a saving of cost and time.

Effect of antigen/antibody ratio on macrophage uptake, processing, and presentation to T cells of antigen complexed with polyclonal antibodies

Activation of a galactosidase-specific murine T hybridoma clone and of a human tetanus toxoid-specific T clone by antigen-presenting cells (APC) was used to evaluate the regulatory function of antibodies complexed with the relevant antigen. Complexed antigen, in fact, is taken up with high efficiency thanks to Fc receptors borne by APC. Antibody/antigen ratio in the complexes proved to be a critical parameter in enhancing antigen presentation. Complexes in moderate antibody excess provided optimal T cell activation independently of the physical state of the complexes (precipitated by a second antibody or solubilized by complement). Complexes in extreme antibody excess, on the contrary, did not yield T cell activation although taken up by APC efficiently. The effect of antibodies at extreme excess was observed with substimulatory dose of antigen (loss of potentiation) and with optimal dose of antigen (loss of stimulation). An excess of specific polyclonal antibodies hampers proteolytic degradation of antigen in vitro, supporting the view that a similar mechanism may operate within the APC that have internalized immune complexes in extreme antibody excess. The possibility that immune complex forming in extreme antibody excess may turn off the T cell response is proposed as a regulatory mechanism.

Monoreactive and polyreactive rheumatoid factors produced by in vitro Epstein-Barr virus-transformed peripheral blood and synovial B lymphocytes from rheumatoid arthritis patients

The CD5 membrane molecule, initially identified as an exclusive T-cell marker, also defines a phenotypically and functionally distinct B-lymphocyte population. In normal individuals, CD5+ B cells are committed to secrete 'natural' polyreactive (auto)antibodies, that is antibodies, mainly IgM, endowed with multiple antigen-binding capabilities, including rheumatoid factor (RF) activity. At variance with this, in rheumatoid arthritis (RA) as well as in other autoimmune conditions, monoreactive autoantibodies binding with high affinity and specificity to a given self antigen have been isolated and the cells from which they originate differently related to the CD5+ B-lymphocyte subset. Here, we studied the proportions of CD5+ B cells and the characteristics, in terms of polyreactivity and monoreactivity, of RF produced by B lymphocytes in RA patients with classified disease activity. Our results suggest that patients with a more severe disease activity have higher proportions of CD5+ B cells and higher frequencies of B lymphocytes committed to secrete RF, with the characteristics of polyreactive antibodies. On the other hand, we did not find a significant difference between the proportions of peripheral B cells producing monoreactive RF in patients with high- versus patients with low-activity RA. However, in two highly active RA patients, we found that synovial fluid, compared with peripheral blood, was significantly enriched for (IgG and IgA) monoreactive RF-producing B cells.

Antibody raised against soluble CD4-rgp120 complex recognizes the CD4 moiety and blocks membrane fusion without inhibiting CD4-gp120 binding

We studied the humoral response of mice immunized with soluble CD4-rgp120 complex, testing polyclonal and monoclonal antibodies (mAbs) with the aim of identifying molecular changes that take place after the first interaction between human immunodeficiency virus and the cell surface. The antisera had a paradoxically high syncytia-blocking titer associated with anti-CD4 specificity, while their capacity to inhibit CD4-gp120 binding was relatively modest. One of the mAbs produced from these responders blocks syncytia formation but does not inhibit CD4 interaction with gp120. Apparently, this mAb interacts with the CD4 moiety of CD4-gp120 complex and prevents a post-binding event necessary for membrane fusion and viral infection.

Use of bispecific hybrid antibodies for the development of a homogeneous enzyme immunoassay

Hybrid bispecific monoclonal antibodies reacting with carcinoembryonal antigen (CEA) and with the E. coli enzyme beta-galactosidase (GZ) were produced by fusion of hybridomas or chemical linkage of half-antibodies. Since the original anti-GZ antibody used in these experiments was capable of protecting GZ from thermal denaturation, it was possible, by hybridizing it with two different non-competitive anti-CEA antibodies, to design a homogeneous enzyme immunoassay for quantitation of CEA. In fact, a mathematical analysis of the reaction indicates that, under appropriate concentrations of the reactants, circular complexes can be formed which contain the two hybrid antibodies, the GZ enzyme and the CEA antigen. The stability of these complexes can be expected to be substantially greater than that of the more labile CEA-free GZ-antibody complexes, prompting a significant increase in the amount of enzyme molecules which are bound to antibody and are consequently protected from thermal denaturation. These expectations were supported by experimental results: under appropriate conditions, heat-resistant enzyme activity was indeed proportional to concentration of CEA in the range up to 75 ng/ml. As predicted by theory, however, in the presence of excess CEA - in fact at CEA concentrations which are higher than those of possible clinical relevance - circular complexes tended to open up, leading to a marked prozone effect.

Sideways killing: the cytolysis of Fc receptor-bearing cells through bridging to cytolytic T lymphocytes by antibodies specific for the T-cell receptor-T3 complex

Cytolytic T lymphocytes (CTL) cause cytolysis of foreign or virus-infected syngeneic cells when recognition of the target plus major histocompatibility complex (MHC) occurs via the T-cell receptor (TCR). The recognition event leads to intimate contact between the two cells and activation of the cytolytic effector. Activation and target cell lysis can also occur in the presence of antibodies to the TCR. This is accomplished by bridging the effector cell TCR to the target cell FcR by an anti-TCR monoclonal antibody (MoAb). Recent findings have placed the role of the FcR in this event in a questionable light. We confirm the importance of Fc gamma R by demonstrating that: (a) melanoma cells are killed by CTL clones in the presence of anti-TCR-CD3 antibodies only when the melanoma cells express the Fc gamma R on their surface; (b) native Ig, heat-aggregated Ig, or an Fc fragment from an antibody expressing the same isotype as the anti-TCR antibody can block the killing of high avidity Fc gamma RI-bearing cells mediated by anti-TCR antibody (F23.1); and (c) anti-Fc gamma R MoAb (2.4G2) and a truncated soluble Fc gamma RII molecule inhibit the killing of low-avidity Fc gamma RII-bearing cells mediated by anti-CD3 MoAb (145-2C11). Thus, we show that both high-avidity Fc gamma RI and low-avidity Fc gamma RII can mediate sideways killing depending upon the isotype of the anti-TCR antibody and the type of FcR present on the target cell surface.

Effect of cyclosporine on the antigen-presenting function of human and murine accessory cells

Recent reports have challenged the belief that accessory cells are resistant to cyclosporine. Such a tenet was based on the observation that several functions of accessory cells, such as IL-1 production and phagocytosis, are resistant to the drug. On the other hand, when a less primitive, more refined function of accessory cells was examined--i.e., the capacity to take up, process, and present antigen in an MHC-restricted fashion to antigen-specific T lymphocytes, CsA proved to be an effective inhibitor. In contrast to this finding, when antigen was provided in the form of an immune complex prepared with a monoclonal antibody, uptake of antigen--likely mediated by the Fc receptors--and subsequent processing and presentation were not affected by CsA. These results suggest that, depending on whether the antigen is taken up by constitutive or by receptor-mediated endocytosis, accessory cells can be functionally defined as resistant or sensitive to CsA.

Differential activation of T cell clones stimulated by macrophages exposed to antigen complexed with monoclonal antibodies. A possible influence of paratope specificity on the mode of antigen processing

We have used the enhanced uptake by FcR-bearing cells observed when Ag is administered as an immune complex to investigate the possible impact of specific antibodies on processing and presentation of antigen by accessory cells. The Ag Escherichia coli beta-galactosidase alone or bound to different mAb was incubated with peritoneal macrophages. These were subsequently exposed to a battery of Ag-specific T hybridoma clones. The resulting production of IL-2 was taken as a measure of effective presentation. The results of 43 mAb-T clone combinations showed a potentiation of presentation of Ag at substimulatory concentration in the majority of the cases, indicating that each mAb is conducive to FcR-mediated uptake by macrophages, and that each T clone can be stimulated by properly presented Ag. In contrast, nine combinations yielded a lower response, two of them falling to baseline values. We attribute these results, which corroborate our previous evidence of directional help in the beta-galactosidase system, to a modulation in enzymatic processing of Ag and its subsequent presentation imposed by the paratope of the mAb binding to the relevant epitope.

Differential activation of T cell clones stimulated by macrophages exposed to antigen complexed with monoclonal antibodies. A possible influence of paratope specificity on the mode of antigen processing

We have used the enhanced uptake by FcR-bearing cells observed when Ag is administered as an immune complex to investigate the possible impact of specific antibodies on processing and presentation of antigen by accessory cells. The Ag Escherichia coli beta-galactosidase alone or bound to different mAb was incubated with peritoneal macrophages. These were subsequently exposed to a battery of Ag-specific T hybridoma clones. The resulting production of IL-2 was taken as a measure of effective presentation. The results of 43 mAb-T clone combinations showed a potentiation of presentation of Ag at substimulatory concentration in the majority of the cases, indicating that each mAb is conducive to FcR-mediated uptake by macrophages, and that each T clone can be stimulated by properly presented Ag. In contrast, nine combinations yielded a lower response, two of them falling to baseline values. We attribute these results, which corroborate our previous evidence of directional help in the beta-galactosidase system, to a modulation in enzymatic processing of Ag and its subsequent presentation imposed by the paratope of the mAb binding to the relevant epitope.

Preferential pairing of T-B specificities in the same antigen: the concept of directional help

It is important for an effective planning of the new generation of vaccines to consider that the eventual response is regulated by the interplay of stimulating and suppressing epitopes, resulting in dominance of certain sites over others, and that in order for a molecule to be crossimmunogenic with the outside invader both B and T epitopes must be present. However, T-B cooperation is not random but is guided by preferential pairing of sites within a single macromolecule; this situation can be explained by antigen processing by B cells and paratope mediated interference with endosomial degradation.

Detection of parasite related antigens associated with conglutinin binding immune complexes in patients with Schistosoma haematobium

An ELISA assay was designed to detect the presence of parasite related antigens associated with circulating immune complexes in patients affected by urinary schistosomiasis. The assay makes use of bovine conglutinin as the immune complex recognition unit and of human anti-Schistosoma antibody as the antigen recognition unit. Using this method we showed that 10 of 15 (67%) patients with a positive polyethylene glycol assay had circulating immune complexes in which parasite antigens could be detected.

Methods for the selection and growth of antigen-specific cytolytic T lines and clones bearing a defined T cell receptor beta chain marker

Murine cytolytic T lymphocyte (CTL) clones specific for type A influenza virus antigens were generated by in vitro stimulation with syngeneic virus-infected cells in the presence of T cell growth factor (TCGF). All CTL clones recognize viral determinants shared by PR8 and X31 influenza viruses in association with a class I antigen, coded either by the H-2K or H-2D end of the appropriate haplotype. All clones express the Lyt2 antigen marker. Two of five clones also express an antigenic determinant of the V beta chain of the T cell receptor (TCR) identified by F23.1 monoclonal antibody. To effectively generate F23.1+ and antigen-specific CTL clones, heterogenous CTL lines were expanded with F23.1 coated Sepharose beads in the presence of TCGF and then stimulated with PR8 virus-infected cells. Thus, both the proliferative activity to PR8 and the expression of the F23.1 marker was increased significantly. Alternatively, F23.1+ T cells were sorted from in vivo primed mice and expanded with PR8 virus-infected stimulator cells in the presence of TCFG. This F23.1+ T cell line exhibited antigen-specific cytotoxicity for PR8 virus-infected target cells. Additionally, in an 'FcR-focused killing' assay only the F23.1+ CTL line and F23.1+ clones lysed Fc receptor bearing target cells in the presence of F23.1 antibody. These findings indicate that antigen-specific and F23.1+ clones can be selected with high efficiency by alternating stimulation with influenza virus-infected cells and with F23.1-coated Sepharose beads or through the use of a cytofluorograph. The usefulness of antigen-specific and F23.1+ CTL clones and other possible strategies for their selection are discussed.

Morphology, cytochemical features, and membrane phenotype of HLA-DR+ interstitial cells in the human pancreas

The morphology, histological distribution, surface, and enzymatic phenotype of pancreatic HLA-DR+ cells were studied on seven human pancreata, removed from cadaver donors. Frozen and paraffin-embedded pancreas sections were stained with a battery of monoclonal antibodies by indirect immunofluorescence, immunoperoxidase, and immunophosphatase techniques. Two type of cells were found to express HLA-DR surface molecules: endothelial cells and nonfibroblastic non-B and non-T interstitial elements. The latter cells, which were localized both in the exocrine and endocrine portions of the organ, were distinguished in two main families (macrophagic and dendritic) according to their morphology, surface phenotype, and lysosomal enzymatic activities. The phenotype of cells belonging to macrophagic cell family was the following: Leu M1+, Leu M2+, Leu M3+, OKM1+, and OKT6-. In addition these cells were positive for the expression of lysosomal enzymes such as alpha-naphthyl acetate esterase (ANAE) and acid phosphatase (AP). The "dendritic" cell family comprised, among others, cells that were characterized by the presence of numerous finger-like projections, the absence of Leu M1, Leu M2, Leu M3, OKM1, OKT6 surface antigens, and by the negativity for ANAE and AP. These "dendritic looking cells" (DLC) constituted the most represented DR+ cell type within pancreatic islets. The demonstration of dendritic cells within human islets may justify, in humans also, in vitro procedures of intra-islet dendritic cell removal prior to transplantation, in the attempt of islet rejection prevention.