Self-reports of health care utilization compared to provider records.

This study compares self-reports of medical utilization with provider records. As part of a chronic disease self-management intervention study, patients completed self-reports of their last six months of health care utilization. A subgroup of patients was selected from the larger study and their self-reports of utilization were compared to computerized utilization records. Consistent with earlier studies, patients tended to report less physician utilization than was recorded in the computerized provider records. However, they also tended to report slightly more emergency room visits than were reported in the computerized utilization records. There was no association between demographic or health variables and the tendency toward discrepancy between self-report and computerized utilization record reports. However, there was a tendency for the discrepancy to increase as the amount of record utilization increased. Thus, the likelihood of bias caused by differing demographic factors is low, but researchers should take into account that underreporting occurs and is likely to increase as utilization increases.

Autoantibodies to T-cell receptor beta chains in human heart transplantation: epitope and spectrotype analyses and kinetics of response.

Autoantibodies against T-cell receptors have been found in two alloimmunization situations in humans: renal transplantation and pregnancy. We carried out longitudinal studies of human heart transplant recipients monitoring their autoantibody production to a recombinant single chain T-cell receptor V alpha/V beta construct, a set of nested, overlapping peptides duplicating the complete covalent structure of an individual T-cell receptor beta chain and a set of peptides duplicating the first complementarity determining segments of 24 distinct human V beta gene products in order to define the time course, epitope specificity and recognition heterogeneity of the response. Autoantibodies against intact and peptide-defined V beta and C beta determinants were generated following human heart allotransplantation. The responses generally show an increase following transplantation that subsequently decreases with time, a result which is consistent with a single immunization. However, some patients showed elevated responses as long as 12 months following the transplant. Autoantibody anti-CDR1 spectrotype analyses detected individual differences among patients, but 5 of 8 patients characterized in detail showed elevated IgG binding to CDR1 peptide epitopes of V beta 6.1, 21.1 and 22.1 gene products. Autoantibodies to CDR1 epitopes of V beta 7.1 and 8.1 were high pretransplant and remained high, although the relative increases with respect to the pretransplant values were not as impressive as those for the above CDR1 epitopes and others usually present in low quantity, e.g. anti-V beta 2.1, 3.1 and 24.1. Although there was great disparity between the MHC haplotypes of donors and recipients, and individual differences among patients, the degree of restriction in the autoantibody response was surprising and suggests a common step in recognition and regulation of the response to allografts.

Construction and serological characterization of a recombinant human single chain T cell receptor.

A single chain T cell receptor (scTcr) was constructed from the complete V alpha and V beta regions of Jurkat T-cell receptor alpha/beta chain genes using molecular cloning techniques. The recombinant scTcr reacted with a panel of rabbit antisera generated against synthetic 16-mer peptides duplicating the amino acid sequence of Jurkat V alpha and beta chains but not with antisera directed against peptides from the constant domain. Autoantibodies present in sera from systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) patients bound the scTcr in ELISA assays. The recombinant scTcr described here should prove to be a useful reagent with which to study T-cell receptor activity in serological and functional assays.

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.

Naturally occurring human autoantibodies to defined T-cell receptor and light chain peptides.

We used synthetic peptides duplicating the structures of a human lambda light chain (Mcg), and a human T-cell receptor (Tcr) alpha and a Tcr beta chain predicted from gene sequence to determine the presence and loci of activity of natural human autoantibodies directed against these antigen recognition molecules. We report that normal individuals and patients suffering from autoimmune diseases have antibodies directed against regions of lambda light chains and Tcr beta chains corresponding to the first complementarity determining region and the third framework region of the variable domain and to constant region determinants. The levels of IgM natural antibodies particularly against the CDR1 peptides tend to be higher in RA patients than in normals or SLE patients. Although polyclonal IgG immunoglobulins from healthy individuals did not show detectable reactivity to Tcr alpha peptides, such reactivity was found in the IgM immunoglobulins of RA patients, thereby showing that Tcr alpha peptides can be autoantigenic in man. The levels of IgM autoantibodies to V beta CDR1 peptides tend to decrease with age. By contrast, there was a marked increase in IgG natural autoantibodies to certain CDR1 sequences with advancing age. We suggest that the natural antibodies to defined regions of immunoglobulins and T-cell receptors are part of a physiological network for the regulation of the immune response.

Cross-reactions of anti-immunoglobulin sera with synthetic T-cell receptor beta peptides: mapping on a 3-dimension model.

The derived amino acid sequences of human T-cell receptor beta chain shows significant homology to lambda light chains of immunoglobulins in its variable, joining, and constant regions. We assessed the cross-reactivity between Tcr beta chains and immunoglobulin light chains by determining the capacity of rabbit antisera to human or murine immunoglobulins to react to a synthesized set of nested, overlapping 16-mer peptides corresponding to the VDJC sequence of the Tcr beta chain YT35. The observed reactivities were consistent with homologies to lambda and kappa light chains, the strongest reactivity being with a peptide that corresponds to the "switch peptide" of light chains, as assessed by ELISA binding and competitive inhibitions assays. Other regions reactive with anti-light chain sera corresponded to CDR1 and Fr3 segments of the variable domain and a segment of the constant region predicted to loop out of the tight globular structure. The peptide immunochemical results, together with the identification of specific regions of sequence correspondence between Tcr beta and the characterized lambda light chain Mcg, allowed us to develop a 3-dimensional model of the beta chain consistent with its role in antigen recognition.

Autoreactive sites of human lambda light chain mapped by comprehensive peptide synthesis.

Autoantibodies reactive against immunoglobulins are associated with autoimmune disorders as well as with immunization and infection. Moreover, recent interest is focused on auto-antidiotypes because of their possible role in immunoregulation. In this study, we used a set of overlapping synthetic peptides duplicating the structure of the monoclonal human lambda light chain Mcg to map autoreactive determinants recognized by natural antibodies present in normal polyclonal human IgG. We found that autoantibodies in human IgG react strongly with two distinct V lambda determinants corresponding to the first complementarity determining region (CDR1) and the third framework (Fr3). Antibodies showing weak reactivities against three regions of the constant domain also occur in the preparations. The antibodies directed against light chain peptides comprise less than 0.1% of the IgG pool. Analysis by direct binding and by competitive ELISA inhibition established that affinity purified antibodies specific for CDR1 and Fr3 peptide determinants react with the intact light chain Mcg as well as with the corresponding peptide. Competitive inhibition studies comparing total IgG and affinity-purified antibodies indicate that natural antibodies showing a wide range of affinities are present. The polyclonal nature of the natural antibodies is further shown by the presence of both kappa and lambda light chains in the purified antibodies. Although the role of such natural antibodies remains to be determined, the cross-reactivity between V lambda peptides and the intact chain suggest that they can function in regulation of antibody formation.

Light and heavy chains specifying a human IgM kappa autoantibody to a T-cell receptor V beta-antigen.

Humans frequently produce serum IgM autoantibodies reactive with T-cell receptor beta chains at a determinant defined by peptides corresponding to the first complementarity determining region. It is likely that this determinant serves as a public idiotype involved in immunoregulation. Following screening of culture supernatants from over 60 Epstein-Barr virus-carrying B-cell lines of normal and neoplastic origin, we identified a line, IARC307, that secretes an IgM kappa protein showing marked specificity for the V beta 8.1 CDR1 sequence CKPISGHNSLFQWYRQT. We cloned and sequenced the complete variable regions of the V kappa and VH chains used by the autoantibody. The light chain has a V kappa III sequence related to the 'a' subgroup and uses J kappa 2. The heavy chain has a VHIII sequence essentially identical to the germ-line sequence DP54 and uses the JH6C minigene. The CDR3 is unique, differing from those of other autoantibodies. The antibody is rigorously specific in its specificity for the V beta 8 peptide and does not show polyspecificity for protein or DNA antigens.

Shared antigenic determinants of immunoglobulins in phylogeny and in comparison with T-cell receptors.

1. Immunoglobulins are a complex multigene family of proteins specified by genes encoding variable (V), sometimes diversity (D), joining (J), and constant (C) domains. 2. Cross-reactions involving conformational determinants related to the VHa system of rabbits occur on heavy chains of vertebrate species ranging from elasmobranchs to man. 3. Serological markers characteristic of mu chains, the heavy chain of the IgM macroglobulins, occur on homologous heavy chains of species representing all vertebrate classes. 4. Serological markers characteristic of gamma type heavy chains, the major isotype in man, are restricted to the mammals, but are found on representatives of even the most primitive mammals, the egg-laying monotremes. 5. Variable region markers characteristic of lambda light chains are shared by light chains of shark and man. 6. Certain idiotypic markers defined by combining site V region sequences are broadly distributed in evolution. 7. Use of synthetic peptides as antigens and in epitope mapping show that amino acid sequences from the third framework region of the variable domain are broadly shared among light chain in phylogeny and between light chains and T-cell receptor beta chains. 8. The "switch peptides" linking the V and C domains of light chains and T-cell receptors, specified by the C-terminal portion of the J segment and the N-terminus of the constant region, are exposed in the three-dimensional structure of immunoglobulin or Tcrs, show striking homology, and form broadly shared antigenic determinants characteristic of immunoglobulins. 9. Although the multigene nature of the immunoglobulins and the complexity of antigenic determinants expressed by these large proteins renders comparison among molecules difficult, serum immunoglobulins and the closely related T-cell receptors express numerous shared determinants defined on the basis of amino acid sequence homology and three-dimensional conformations.

Reactions of anti-immunoglobulin sera with synthetic T cell receptor peptides: implications for the three-dimensional structure and function of the TCR beta chain.

The derived amino acid sequence of the human TCR beta chain shows considerable homology to lg lambda light chains in its variable (V) and constant (C) domains, and in its joining segment (J). We assessed the cross-reactivity between TCR beta chains and lg light chains by synthesizing a set of nested, overlapping 16-mer peptides that duplicated the sequence that corresponds to the continuous VDJC sequence of TCR beta chain and determining the capacity of rabbit antisera to human or murine lgs to react with these peptides. The reactivities we observed were consistent with homologies to lambda and kappa light chains. The strongest reactivity in ELISA binding and competitive inhibition was with a peptide that corresponds to the 'switch peptide' of light chains. The sequence is encoded by the C-terminal region of the J segment (Fr4) and the N-terminus of the C region. Other regions reactive with anti-light chain sera corresponded respectively to CDR1 and Fr3 segments of the V region, and a segment of the constant region predicted to loop out of the tight globular structure. The peptide immunochemical results, coupled with the identification of specific regions of sequence correspondence between TCR beta and the characterized lambda light chain Mcg, allowed us to develop a three-dimensional model of the beta chain consistent with its role in antigen recognition and response to superantigens.

Human autoantibodies to a synthetic putative T cell receptor beta-chain regulatory idiotype: expression in autoimmunity and aging.

We used synthetic peptides to analyze the human natural antibody response to V beta determinants. A major determinant recognized by IgM and IgG autoantibodies of clinically healthy individuals as well as those suffering from rheumatoid arthritis (RA) was a peptide corresponding to the first complementarity-determining region (CDR1). The natural IgM response of RA patients to this synthetic autoepitope was significantly elevated relative to that shown by healthy individuals. The levels of IgM reactivity to determinants corresponding to this region decreased with increasing age. By contrast, IgG autoantibodies to certain V beta CDR1 peptides increased markedly with age. In order to determine whether the CDR1 V beta determinant might be involved in immunization, we immunized rabbits with a human peptide that is greater than 80% identical to the homologous sequence derived from a rabbit V beta gene. As a control, the rabbits were immunized with a peptide of equal length derived from the N-terminus of the human V beta chain. Like humans, rabbits tended to have high levels of autoantibodies to the CDR1 peptide but not to the N-terminal segment. Following immunization, the rabbits produced strong IgG responses to the N-terminal peptide. By contrast, immunization with the CDR1 peptide resulted in levels of IgG antibody less than or equal to the natural activity in unimmunized rabbits. These studies indicate that the CDR1 region of Tcr V beta is a widely recognized autoantigenic portion of the Tcr that most probably functions as a regulatory epitope in man and other species.

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.

Human autoantibodies reactive with synthetic autoantigens from T-cell receptor beta chain.

We used mapping with synthetic overlapping peptides in combination with molecular modeling to analyze the IgG antibodies that humans naturally produce against human T-cell receptor beta chains and to localize the recognized peptide autoantigens in the three-dimensional structure of the molecule. Healthy individuals produce low levels of antibodies against T-cell receptor peptides, and these can be increased in autoimmune diseases. We characterized the reactivities in detail because IgG molecules reactive with self peptides occur in preparations of intravenous immunoglobulin and can be isolated by immunoaffinity chromatography. Natural IgG antibodies were directed against three major peptides. One corresponds to the first complementarity-determining region of the variable region. A second corresponds to the third framework of the variable region. The third is located in the constant region and is predicted to be a loop that extends out of the beta-barrel structure. This peptide is one that would give a characteristic structural distinction between the beta-chain constant region and the constant regions of immunoglobulin light chains to which beta chains are homologous. The capacity to bind these peptides is found in small fractions of normal polyclonal IgG, which contains both kappa chains and lambda chains. The activity is antibody-like in being confined to the Fab fragment and in its capacity to discriminate among homologous synthetic peptides corresponding to distinct beta-chain variable-region genes. We propose that a recognition and regulatory process naturally occurs that parallels the immune network for the regulation of the production of antibodies.

Antigenic mapping of a human lambda light chain: correlation with three dimensional structure.

Although the amino acid sequence and three-dimensional structure of human immunoglobulin light chains have been known for more than 15 years, the location of antigenic markers characteristic of lambda chains has not been determined. Here, we use a set of synthetic overlapping peptides to completely model the sequence of the lambda chain Mcg and test these for the binding of rabbit and goat antisera specific for lambda chain determinants. We assess peptide contributions to lambda-antigenic reactivity and also to identify a portion of C-region where conformational factors contribute to the antigenicity. Specific determinants occur both in the constant and variable (first and third framework) domains of the molecule. The fourth framework of the variable region, a segment specified by the joining gene, is also recognized and cross-reacts antigenically with the homologous region of T cell receptor beta chains. Major lambda specific determinants are localized in the N- and C-terminal segments, which are linear and devoid of major conformational folding. Other segments that are strongly antigenic, such as the third framework of the V region (residue 78-93) and a segment of the constant region (residues 177-192), show strong conformational dependence in antigenicity.