Healthcare utilization and unmet needs of patients with antisynthetase syndrome: An international patient survey.

Antisynthease syndrome (ASSD) is a rare, complex and understudied autoimmune disease. Internet-based studies can overcome barriers of traditional on-site research and are therefore very appealing for rare diseases. The aim of this study was to investigate patient-reported symptoms, diagnostic delay, symptoms, medical care, health status, working status, disease knowledge and willingness to participate in research of ASSD patients by conducting an international web-based survey. The multilingual questionnaire was created by an international group of rheumatologists and patients and distributed online. 236 participants from 22 countries completed the survey. 184/236 (78.0%) were female, mean age (SD) was 49.6 years (11.3) and most common antisynthetase antibody was Jo-1 (169/236, 71.6%). 79/236 (33.5%) reported to work full-time. Median diagnostic delay was one year. The most common symptom at disease onset was fatigue 159/236 (67.4%), followed by myalgia 130/236 (55.1%). The complete triad of myositis, arthritis and lung involvement verified by a clinician was present in 42/236 (17.8%) at disease onset and in 88/236 (37.3%) during the disease course. 36/236 (15.3%) reported to have been diagnosed with fibromyalgia and 40/236 (16.3%) with depression. The most reported immunosuppressive treatments were oral corticosteroids 179/236 (75.9%), followed by rituximab 85/236 (36.0%). 73/236 (30.9%) had received physiotherapy treatment. 71/236 (30.1%) reported to know useful online information sources related to ASSD. 223/236 (94.5%) were willing to share health data for research purposes once a year. Our results reiterate that internet-based research is invaluable for cooperating with patients to foster knowledge in rare diseases.

Online Nano Solid Phase Extraction Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry Workflow to Analyze Small Scale Gradients of Soil Solution Organic Matter in the Rhizosphere.

A new method combining online nano solid phase extraction coupled with Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was developed to extract and analyze organic matter (OM) from microliter volumes of salt containing soil solution samples. This approach allows the reproducible analysis of only minute amounts of organic carbon (down to 10 ng C) without the need of further sample preparation. The new method was applied to unravel developing small-scale patterns of dissolved organic matter (DOM) in soil solutions of a soil column experiment in which Zea mays plants were grown for 3 weeks. Soil solution was sampled by micro suction cups from the undisturbed soil-root system once a week. Growth of the root system and, hence, position of individual roots relative to the suction cups was followed by X-ray computed tomography (X-ray CT). Our method makes it possible to resolve the chemical complexity of soil solution OM (up to 4300 molecular formulas from 2.5 µL sample). This allows to observe chemical gradients in the rhizosphere on a molecular level over time. The increasing influence of roots on soil solution OM is visible from higher molecular masses, an increasing degree of oxygenation and a higher fraction of formulas containing heteroatoms. The online nano solid phase extraction-FT-ICR-MS method provides novel insight into the processes affecting DOM in the rhizosphere, such as root exudation, microbial processes, and soil organic matter stabilization.

On the challenges of measuring interfacial characteristics of three-phase fluid flow with x-ray microtomography.

Synchrotron-based x-ray computed microtomography contributes high-resolution, three-dimensional observations to investigations of multiphase fluid transport in porous media. Pore-scale observations are valuable to the development and validation of new theory, as well as numerical models. Computed microtomography has been used previously to measure fluid content and interfacial areas in systems containing two fluids (air-water, oil-water) and to a limited extent to measure fluid content and entrapped fluid morphology in systems containing three fluids (air-oil-water). This study addresses challenges that arise when imaging three-phase flow in spreading systems. The first challenge is related to wettability alteration. Observations reported herein suggest that the wettability of solid surfaces changed over the course of a three-fluid phase flow experiment, a phenomenon that has not been observed in similar, previously conducted two-fluid phase experiments. Follow-up experiments showed that wettability alteration is significant when oil-solid contact is combined with x-ray exposure, and is not reversed with a conventional cleaning procedure. The second challenge arises in segmenting three-phase images, and thereby obtaining data from which various measures can be quantified with sufficient accuracy. Partial volume effects and blur often cause the grey-scale values of different fluids to overlap and appropriate steps must be taken to avoid ambiguity at phase boundaries. A comparison of images collected at standard resolution (10.6 microns voxel(-1) ) to those collected at a higher resolution (5.3 microns voxel(-1) ) showed that saturation measurements are within 5% of each other, but interfacial areas for three-phase systems may be underestimated at standard resolution by as much as 25%.

Phase I study of direct gene transfer of an allogeneic histocompatibility antigen, HLA-B7, in patients with metastatic melanoma.

PURPOSE: To determine the safety, toxicity, and efficacy of direct intratumoral injection of an allogeneic major histocompatibility complex (MHC) class I gene, HLA-B7, in a cationic lipid vector (Allovectin-7; Vical Inc, San Diego, CA) in patients with metastatic melanoma. PATIENTS AND METHODS: Seventeen HLA-B7-negative patients were treated with intralesional injection of Allovectin-7. Twelve patients received a single intralesional injection containing 10 micrograms (four patients), 50 micrograms (five patients), or 250 micrograms (three patients) of plasmid DNA. Five patients received two or three injections of 10 micrograms DNA to a single tumor site at 2-week intervals. Tumor biopsies pretherapy and 2 and 4 weeks after gene injection were obtained to determine expression of the plasmid by polymerase chain reaction (PCR), reverse transcriptase (RT)-PCR, flow cytometry, and immunohistochemistry. RESULTS: Toxicities were related to technical aspects of the injections or biopsies. These included pain, hemorrhage, pneumothorax, and hypotension. Two patients were hospitalized overnight for observation. Seven patients (50%) had tumor responses insofar as the injected nodule decreased > or = 25% by radiologic or physical examination. One patient with a single site of disease achieved a complete remission. Ninety-three percent of the patients' post-gene therapy biopsies contained HLA-B7 plasmid DNA, mRNA, or protein. CONCLUSION: Intratumoral injection of the allogeneic histocompatibility gene, HLA-B7, in a lipid vector can be performed safely at plasmid DNA doses < or = 250 micrograms. The safety profile and biologic activity of this therapy warrants further studies to define the mechanism of action, predictors of response, and antitumor efficacy of this approach.

Immunomodulation by immunopeptides and autoantibodies in aging, autoimmunity, and infection.

The operation of the immune system is a complex orchestration of specific self and non-self-recognition capacities mediated by cells of the innate system acting in coordination with T and B lymphocytes in a series of processes modulated by cytokines. We provide evidence for a natural immunomodulatory system involving autoantibodies directed against a controlling segment of T cell receptor Vbeta chains that downregulate production of stimulatory cytokines balanced by the peptides which in turn upregulate inflammatory activities mediated by TH1-type helper cells. TCR Vbeta-derived peptides effective in retrovirally induced immunosupression could also reverse the effects of immunosenescence in aged mice by restoring the balance of TH1- and TH2-type immunity and the resistance of the animals to cardiac pathology caused by infection with coxsackievirus. An unexpected finding was an adaptive role of the T cells from peptide-treated mice in remodeling damaged hearts by increasing net collagen synthesis by cardiac fibroblasts.

Binding of human IgG myeloma proteins to autologous T-cell receptor determinants.

IgG myeloma proteins (MPs) produced by monoclonal plasma cells derived from B2 lymphocytes have been reported to bind to various autoantigens but the binding generally has been of low affinity. Moreover, T cells from some multiple myeloma patients can respond specifically to idiotypes of their own paraproteins. We analyzed the capacity of more than 20 human IgG MP to bind, a recombinant single-chain molecule containing complete V beta 8.1 and V alpha 1 structures, sets of synthetic peptide epitopes corresponding to a complete TCR beta chain, and a set of CDR1 epitopes corresponding to 24 human V beta gene products, and intact monoclonal T cells. Two of 20 MPs bound strongly to the recombinant TCR. Five of the same set, including these, bound to a synthetic epitope corresponding to the CDR1 segment. On a mass basis, the binding was approximately 1000-fold greater than that of pooled polyclonal IgG. The binding activity was confined to the Fab fragment and was specifically inhibitable by appropriate peptide determinants. Spectrotypic analysis using a set of CDR1 epitopes indicated that individual proteins showed characteristic binding patterns ranging from highly specific to relatively promiscuous. Highly reactive MPs also bound to TCR on intact cells in immunocytofluorescence by flow cytometry. These results are consistent with the relatively frequent occurrence of autoantibodies to TCR determinants and indicate that MPs can be derived from this autoantibody subset.

Immunoglobulin epitopes defined by synthetic peptides corresponding to joining region sequence: conservation of determinants and dependence upon the presence of an arginyl or lysyl residue for cross-reaction between light chains and T-cell receptor chains.

Joining or J region sequences of rearranging immunoglobulins and T-cell receptors show considerable sequence homology, particularly in their C-terminal portion corresponding to the fourth framework region of immunoglobulin variable regions. In order to test the question of whether serological cross-reactions between immunoglobulin variable regions and T-cell receptors were due to antigenic similarities in their J regions, we synthesized synthetic peptides corresponding to immunoglobulin J regions and to J regions predicted from gene sequence of the T-cell receptor beta chain. We found that antibodies produced against a synthetic 16-mer J beta sequence reacted with T-cell receptor chains and also with immunoglobulin light chains. The cross-reactivity was dependent upon the J signature sequence FG()GT(R or K)L where the presence of a positively charged lysyl or arginyl residue was essential for cross-reactivity. We were able to classify J region determinants into two distinct antigenic sets; one corresponding to JH and the other corresponding to J kappa, J lambda, J beta and J alpha. Although considerable homology occurs between JH and JL (or J beta) sequences, little cross-reactivity was observed between these two J subsets. Antibodies raised against polyclonal murine IgG immunoglobulins contained antibody subpopulations specifically reactive with either JH or J beta peptides. The serological data derived here using antipeptide antibodies are consistent with computer modeling studies that indicate that the conformations of T-cell receptor variable regions resemble those of classical immunoglobulins. Our data comparing cross-reactivities restricted to the J region indicate that the expression of the J region by intact T-cell receptor beta chains is probably more similar to that of light chains than it is to the corresponding region of heavy chains.

Sequence analysis of homogeneous peptides of shark immunoglobulin light chains by tandem mass spectrometry: correlation with gene sequence and homologies among variable and constant region peptides of sharks and mammals.

Morphologically, sharks are living fossils that are remarkably similar to their Devonian ancestors of ca. 400 million years ago. If a parallel conservation in biochemical properties characterizes shark evolution, knowledge of the properties of shark immunoglobulins should provide information on the structure of primordial immunoglobulins and their genes. The problem of polyclonality of shark immunoglobulins has precluded detailed analysis of shark immunoglobulin light polypeptide chains. Here, we approach the problem of obtaining direct sequence information on polyclonal light chains of shark immunoglobulins by isolating homogeneous peptides from tryptic digests of shark light chains and sequencing these by tandem mass spectrometry. To confirm the location of the peptides, we isolated a complementary DNA (cDNA) clone from a sandbar shark cDNA library in the expression vector lambda gt11, identifying the clone by its ability to produce a peptide serologically detectable using rabbit antibody to purified shark light chain. The correspondence between peptide sequence and that derived from gene sequence provided direct proof that the gene studied was that of a major expressed serum light chain. Using this combined approach, we isolated homogeneous peptides from both constant and variable regions. The variable region peptides showed homology to corresponding sequences of mammalian V lambda and V kappa sequences. The constant region gene sequence we obtained was homologous to mammalian C lambda sequence. The four constant region tryptic peptides we sequenced corresponded exactly to stretches of the C lambda sequence derived from the DNA sequence. The combined approach described here shows that shark light chains exhibit heterogeneity at both the protein and gene level, but that the constant regions of these chains can be identified as homologs of mammalian lambda chains and that evolutionary conservation has occurred in V region sequences ranging from elasmobranchs to man.

Lack of preferential V beta usage in synovial T cells of rheumatoid arthritis patients.

The T-cell receptor V beta subfamily repertoires of synovial and peripheral T cells of 8 rheumatoid arthritis (RA) patients were determined using the polymerase chain reaction. Three normal controls were included. Some of the rheumatoid synovial samples did not express the complete range of V beta families and lacked as many as 6 gene families. However, these patients showed considerable individual variation in expression. Overall, the data do not support preferential T-cell receptor V beta usage in synovial T cells of RA patients either in comparison to their autochthonous peripheral T cells or to peripheral T cells of normal subjects.

Antibodies to synthetic peptides corresponding to variable-region first-framework segments of T cell receptor. Detection of T cell products and cross-reactions with classical immunoglobulins.

Recent studies at the gene level have shown that T cells express rearranged genes for four types of T cell receptors that are strongly homologous to classical immunoglobulins in the joining region and in the framework 1 (Fr1) and 3 segments of the variable region. Based upon the homologies in gene sequence, it follows that the gene products would show similarities in amino acid sequence and in the folding of the proteins so that cross-reactivities in antigenic determinants would be expected between variable regions of the T cell receptors and classical immunoglobulins. We have synthesized peptides corresponding to predicted protein sequences of the Fr1 residues of T cell receptor alpha, beta- and gamma-chains and have produced antibodies in rabbits against these synthetic peptides. Use of antisera and affinity-purified antipeptide antibodies indicated that high-titer antibodies could be raised that were specific for individual Fr1 peptides. Cross-reactions among Fr1 peptides of T cell receptors and immunoglobulin light chains were observed. In addition, some rabbit antisera raised against classical polyclonal immunoglobulins or affinity-purified immunoglobulin-like T cell receptors were found to exhibit binding activity against Fr1 peptides of T cell receptor beta- and gamma-chains. The sequence homology, although real among the Fr1 of T cell receptors and immunoglobulin light chains, is moderate and the antigenic cross-reaction must reflect the configuration and types of amino acids present. The development of antipeptide antibodies holds promise for the characterization of T cell receptors of various T cell sources and also offers a new means for the identification of molecules related to rearranging immunoglobulins.

Expression of an antisense transforming growth factor-beta1 transgene reduces tumorigenicity of EMT6 mammary tumor cells.

Transforming growth factor-beta (TGF-beta) is a potent immunosuppressive cytokine produced by many tumor cells. Secretion of TGF-beta by malignant cells may therefore be a mechanism by which tumor cells escape destruction by tumor-specific T lymphocytes. In order to evaluate the role of tumor-derived TGF-beta on tumor progression, we have inhibited the production of this cytokine by introducing a gene encoding antisense TGF-beta1 into the EMT6 murine mammary tumor cell line using a retroviral vector (Las-TGF-beta1SN). EMT6 cells transduced with this vector (EMT6as-TGF-beta1) stably expressed the antisense gene and secreted 52% less TGF-beta than did tumor cells transduced with the backbone vector alone. Supernatant fluid recovered from tumor cells expressing the antisense TGF-beta1 gene also exhibited a decreased capacity to inhibit alloantigen-specific cytotoxic T-cell responses in vitro. Furthermore, tumor growth in mice injected with EMT6as-TGF-beta1 tumor cells was inhibited compared to mice injected with control tumor cells. These results demonstrate that expression of antisense TGF-beta1 by transduced EMT6 cells decreases their tumorigenicity and suggest that this approach of eliminating immune suppression is a potentially useful strategy to enhance antitumor responses.

The interaction of lactose-specific lectins with acid-treated and lactose-substituted sepharose.

The binding of two lectins, one a galactosyl/lactosyl and the other a lactosyl binding protein, to various Sepharose 4B derivatives has been investigated. The adsorbents, lactose-substituted Sepharose, acid-treated Sepharose and acid-treated, lactose-substituted Sepharose, were each tested with regard to their overall binding capacity and for the ability to separate the lectins by differential elution with solutions of galactose and lactose. The binding capacity for both lectins decreased in the order Lac-acid-Sepharose greater than Acid-Sepharose greater than Lac-Sepharose much greater than Untreated Sepharose. The ability of the gels to bind both lectins with a sufficient affinity to allow the proteins to be purified by differential elution decreased in a similar order. Acid-treated, lactose-substituted Sepharose proved the most useful gel and was utilised to isolate each lectin in a pure form.

Schmidt-Lanterman's incisures--the principal target of autoimmune attack in demyelinating Guillain-Barré syndrome?

We used immunocytochemical staining of peripheral (trigeminal) nerve to screen sera of patients with Guillain-Barré syndrome (GBS) for the presence of autoantibodies, using sera from patients with other neurological diseases and healthy volunteers as controls. Most sera mildly reacted with axons, myelin sheaths, or sensory neurons without correlation to a specific disease. A characteristic staining, however, was found in 23 demyelinating cases (89%) out of 26 investigated GBS sera. With these sera, dark, oval and often paired small blobs were observed throughout the sections. A similar picture was rarely observed with sera from patients with other disorders or healthy controls. Using immunocytochemical marker proteins and high light microscopic resolution, the blobs were identified as Schmidt-Lanterman's incisures (SLIs). Further investigations will be necessary to identify the corresponding antigen and to answer the question, whether these antibodies represent an epiphenomenon or play a role in the causative mechanism of the disease.

Immunoproteins in evolution.

All vertebrates respond to antigenic challenge by specific cellular reactions and by producing circulating antibodies, and they also contain recognition molecules that are evolutionary relics of primitive non-immune recognition. One such ancient recognition molecule is C-reactive protein (CRP), a member of the pentraxin family, that has homologs occurring in species as diverse as vertebrates, tunicates and the horseshoe crab (an ancient arachnoid). This molecule has lectin-like properties, can act as an opsonin and interact with complement and cells in a manner paralleling immunoglobulins (Igs). The horseshoe crab lectin and CRP, although unrelated to Igs, share functional idiotopes with classical antibodies. This finding reflects either an evolutionary convergence or a mechanism of "mini gene insertion" that allows molecules of distinct evolutionary histories to react to the same ligands. Serum antibodies of all vertebrates are polydisperse in charge and are composed of polypeptide chains comparable in mass to those of mammalian light and heavy chains. Molecular genetic studies of placoderm derived vertebrates are incomplete but are sufficient to allow the conclusion that Igs of these species are specified by variable (V), joining (J) and constant (C) gene segments and that rearrangement are an essential feature for the generation of antibody diversity. Here we present new evidence following from the use of antibodies directed against synthetic joining region peptides as probes in the study of rearranging Igs in evolution, the use of recombinant DNA technology to study T cell receptor V beta genes in a goldfish genomic library and the isolation and characterization of a gene fragment specifying sandbar shark light chain C region. We reached the following conclusions: (1) J region segments are the most conserved in evolution, and this most probably reflects the essential requirements for these gene segments in the formation of intact Ig genes by rearrangement; (2) the framework segments of V regions are highly conserved in vertebrate evolution for both T cell receptors and classical Igs; and (3) although C region segments of light chains of lower vertebrates are homologous to their mammalian counterparts, the degree of conservation of C region structure in phylogeny is apparently less than that for V regions. Essentially, phylogenetic trees can be built using C regions but not V regions. We have identified a molecule of approximate mass of 26 kDa in the hemolymph of the tunicate, Boltenia ovipera, that is serologically cross-reactive with shark heavy chain and with J region peptides.(ABSTRACT TRUNCATED AT 400 WORDS)

Antibody production in sharks and humans: a role for natural antibodies.

Although gene segments specifying Igs of all vertebrates show clear homology, their arrangements differ markedly, thereby suggesting that the mechanisms for the generation of diversity and for the regulation of gene expression may be quite distinct. In the sandbar shark, light chain gene segments are distributed as apparently independent clusters consisting of V, J, and C elements that require rearrangement for expression. The usual distance between V and C in the clusters is 3 kb but larger clusters occur. The V, J, and C elements are clearly homologous to those of human lambda chains. Shark Igs resemble mammalian IgM in structure and gene similarity. IgM may comprise as much as 50% of serum proteins in the shark. By contrast, IgM in humans comprises less than 5%. Human autoantibodies usually are IgM. These show little dependence on thymic function for expression and tend to increase with age. We have carried out a study of the capacity of Igs of unimmunized sharks and people (normals and patients suffering from autoimmune diseases) to react against a panel of antigens, including those usually considered autoantibodies, such as thyroglobulin and single-stranded DNA. Sharks and humans possess IgM antibodies that react with thyroglobulin and ssDNA. Affinity-purified natural shark antibodies to thyroglobulin or ssDNA constitute small fractions of total IgM. They illustrate extensive cross-reactivity comparable to that shown by polyspecific IgM autoantibodies produced by human B cells (CD5+) that appear early in ontogeny.

Partial characterization of immunoglobulin light chains of carcharhine sharks: evidence for phylogenetic conservation of variable region and divergence of constant region structure.

Isolated light chains of IgM-type immunoglobulins of carcharhine sharks were analyzed by serological and biochemical means. When analyzed by isoelectric focusing analysis, light chains of the tiger shark (Galecerdo cuvieri), the galapagos shark (Carcharhinus galapagensis) and the sandbar shark (Carcharhinus plumbeus) showed a broad, but patterned, spectrum of bands ranging from pI 5.0 to 7.7 in which discrete families were observed. Serologically, light chains of the galapagos shark cross-reacted with rabbit antibodies against mouse immunoglobulin and a synthetic peptide corresponding to the J segment of T cell receptor beta chain. The latter cross-reaction is shared among light chains and T cell receptors. Although there was considerable heterogeneity in isoelectric focusing analysis, the light chains were homogeneous on the basis of apparent mass (23 kDa) and those of tiger shark and galapagos shark had relatively homogeneous dominant N-terminal sequences representing the first framework. The N-terminal sequences of these two shark light chains, were strongly homologous to one another and showed 75% identity to certain V kappa sequences of man and dog. Homology was also shown to V lambda sequences, but the degree of identity was approximately 50%. Following cleavage of the tiger shark light chain with o-iodosobenzoic acid which cleaves at tryptophanyl residues, a constant region peptide was isolated by gel filtration. It was possible to identify the homolog of this peptide within the constant regions of mammalian kappa and lambda chain, but the relationship to C kappa chain was stronger. The degree of identity among the corresponding C region peptides of mammalian, avian and elasmobranch species was much less than that observed for the framework 1 sequence of the light chain variable region. These data support the concept that variable and J region sequence have been conserved in the evolution of placoderm-derived vertebrates, but that constant regions show much greater phylogenetic variation.

Identification of the HA-2 agglutinin in the haemolymph of the ascidian Botrylloides leachii as the factor promoting adhesion of sheep erythrocytes to mouse macrophages.

The HA-2 agglutinin purified from B. leachii haemolymph is shown to mediate the binding of sheep erythrocytes to mouse macrophages. This agglutinin appears to be wholly responsible for the adhesive activity of haemolymph, since upon chromatography of the latter through Sephadex G-200, the adhesive activity for both sheep and guinea pig erythrocytes was confined to those fractions containing the HA-2 agglutinin. The HA-1 agglutinin recovered in earlier fractions was unable to promote the adhesion of guinea pig erythrocytes to macrophages. Adsorption experiments indicated that this was due to a lack of ligand sites on the macrophage surface. These data support earlier conclusions that the HA-1 and HA-2 agglutinins have distinct binding specificities.

Development of an immune system.

Minimally, an immune response is an induced cellular and/or humoral defense mechanism specific for the challenging agent. The system is a cognitive one inasmuch as a second stimulus with the same antigen can specifically induce either an enhanced response (memory) or diminished response (tolerance). The cells responsible for the initial antigen-specific recognition in higher vertebrates are clonally restricted T and B lymphocytes. Accessory cells are necessary for the processing and presentation of antigen, and physiologic mediators (cytokines) are essential for proliferation, interaction, and regulation of the system. Although it now appears that the recombination mechanisms essential for the anticipatory immune response occurred late in the deuterostome stream leading to vertebrates, molecules required for cell adhesion and regulation are widely spread in phylogeny. Their emergence must have preceded the divergence between ancestral protostomes and deuterostomes. Genetic mechanisms underlying the generation of diversity in the light and heavy chains of antibodies of mammals may be quite distinct in primitive vertebrates, particularly elasmobranchs, the ancestors of which diverged from those of mammals more than 400 million years ago. Despite this, clonal selection of antigen receptors of lymphocytes is most probably universal within the vertebrates. There is no need to force induced recognition in protostomes (e.g. insects) or lower deuterostomes (e.g. echinoderms) into mammalian models of immunity.

Recognition molecules and immunoglobulin domains in invertebrates.

We have used specific antibody probes to conserved antigenic motifs to identify and characterize immunoglobulin-related molecules in tunicates and a C-type lectin found in lamprey that is related to molecules found in tunicates and mammals. The tunicate immunoglobulin cross-reactive molecule (mu CRM) reacts with antibodies raised to shark IgM heavy chains. Intact tunicate mu CRM is a monomer of Ig light-chain-sized subunits and is oligoclonal by IEF. That this molecule is related to Ig is indicated both by immunochemical data and by peptide sequence homologies. The lamprey lectin is a large polymer (> 500,000 kDa) of 35-kDa and 60-kDa subunits. It appears to be related to C-type lectins as shown by peptide sequence homology and the requirement of Ca2+ for activity. Related molecules appear to be present in tunicates and mammals as shown by cross-reactivity of antibodies in Western blots with single bands from hemolymph and T-cell extracts.

Cell surface recognition and the immunoglobulin superfamily.

Immunoglobulins serve as humoral recognition and effector molecules and as antigen-specific cell surface receptors on B and T cells. These molecules are constructed according to a characteristic domain pattern. Variable and constant domains diverged from one another early in vertebrate evolution, and they are joined by a "switch peptide" specified by the joining gene segments. Peptides specified by J-gene segments are strongly conserved in evolution in comparison among Ig light chains and T-cell receptors. Molecules less strongly related to Ig domains have been assembled into an Ig "superfamily" where the identities to classical IgC or V domains are < or = 20%. Among these are cell surface adhesion molecules, receptors for cytokines, and Fc receptors. Moreover, MHC antigens have an Ig-like membrane-proximal domain significantly related to IgC regions. We will analyze putative evolutionary relationships among canonical Igs and members of the Ig superfamily using highly conserved sequences from light and heavy chains of primitive vertebrates (e.g., the sandbar shark) as prototypes to ascertain similarities between Ig-related molecules of vertebrates and invertebrates.