Delineation of a cross-reactive idiotype on human autoantibodies with antibody against a synthetic peptide.

We investigated the immunochemical and molecular characteristics of murine monoclonal rheumatoid factors. Study of the fine specificity of 20 monoclonal rheumatoid factor antibodies shows a wide degree of heterogeneity. However, many express an interstrain cross-reactive idiotype. We show that our rheumatoid factors utilize a restricted set of the heavy-chain variable region (VH) repertoire representing the more 3' VH families. Preferential expression of 3' VH families is known to occur early in development. We report the nucleotide sequence of two cloned rheumatoid factor VH genes, Y19-10 (VH J558) and 129-48 (VH 7183) in which no major differences are observed between VH genes encoding the heavy chain of autoantibodies and antibodies against foreign antigens.Antibodies directed against determinants of self IgG were first observed in the sera ofpatients with rheumatoid arthritis (1). Such antibodies, termed rheumatoid factors (RFs), can bind with a low affinity to the antigenic determinants expressed on the Fc fragment of autologous IgG (2). Later, RFs were found to be associated with various autoimmune diseases including systemic lupus erythematosus (3). The nature and origin of the RF response are still poorly understood. We have used murine RF monoclonal antibodies as models to study the immunochemical and molecular properties of autoantibodies. In this report, we present the following results. (i) Our monoclonal RFs, either spontaneous in nature or produced by induction, were predominantly of the ,u isotype and are multispecific. (ii) They express a high degree ofidiotype (Id) cross-reactivity, yet use different heavy-chain variable region (VH) gene segments. (iii) Regardless of their mouse strain origin, RFs use genes from a restricted number of VH gene families, namely J558, QPC52, and 7183. Sequence analysis revealed that the RF VH genes are closely related to germ-line genes that are used to encode antibodies to exogenous antigens. (iv) Id cross-reactivity may be due to a common tetrapeptide in framework 2 of the VH region.MATERIALS AND METHODS Animals. Six-month-old 129/Sv, 5-month-old MRL/lpr, and 3-month-old BALB/c mice, obtained from The Jackson Laboratory, were utilized in the preparation of hybridomas. Young adult female New Zealand White rabbits obtained from The Jackson Laboratory were used to prepare anti-Id antisera.Induction of RFs. BALB/c splenic lymphocytes cultured in RPMI supplemented with 20% (vol/vol) fetal calf serum were stimulated with Escherichia coli lipopolysaccharide (50 ,ug/ ml) for 4 days.

Section: Discussionmentioning

confidence: 99%

Fine specificity, idiotypy, and nature of cloned heavy-chain variable region genes of murine monoclonal rheumatoid factor antibodies.

Manheimer-Lory¹,

Monestier²,

Bellon³

et al. 1986

“…Idiotypic determinants are autoantigens recognized by the immune system. The surface nature of idiotypic sequences is evidenced by anti-peptide antibodies interacting with intact immunoglobulin molecules (13)(14)(15)(16)(17)(18) and analysis of crystallographic structures of Fab fragments (19,20) and related proteins (21). Herein, a method is described that does not score surface-neutral substitutions in the analysis of evolutionary variability.…”

mentioning

confidence: 99%

Evolutionary origin of autoreactive determinants (autogens).

Kieber‐Emmons¹,

Köhler²

1986

The question addressed in this report focuses on the autoantigenicity of self antigens, principally cytochrome c and lysozyme. Autoimmune disease is thought to result from an abnormal reaction of the immune system against self. The maintenance of self-tolerance is the result of complex immune regulatory mechanisms established by the immune network (1). The concept of regulatory control mechanisms implies that the immune system is intrinsically able to recognize self. However, it is not clear whether self determinants are randomly selected by the immune system as targets or whether certain determinants are more prone to become autoantigenic. A favored hypothesis for autoreactivity states that immunological cross-reactivity between self and foreign antigen structures can bypass normal control mechanisms preventing autoimmune response. In an alternative explanation for the molecular basis of autoreactivity, the coevolution of self components and the immune system has been proposed to be a determining factor (2-6), leading to the proposition of a multideterminant regulatory model for autoreactivity (2). This model implies that the response to selfproteins has been directed against those sequence regions that exhibit the highest evolutionary instability. It has been argued that insufficient time in evolution did not permit the elimination of self-reactive clones recognizing recent evolutionary substitutions in proteins (2, 3).Typically, the evolutionary diversity of proteins is evaluated by the simple analysis of sequence variation (7). Jemmerson and Margoliash (3), using the variability approach of Wu and Kabat (7), demonstrated several sequence areas of variability on mammalian cytochrome c. Three of these peak areas coincided with experimentally determined autoreactive determinants in rabbits. In a predictive manner, the analysis of sequence variability does not, in general, discriminate between substitutions affecting and not affecting the antigenic structural properties of proteins. While an amino acid outside of an epitope may not directly affect determinant recognition (8, 9), such surface-neutral substitutions are registered by sequence variability plots. This condition is best typified by immunoglobulins whereby the sequence variability of the hypervariable regions can affect either antibody binding (10) or idiotypic activity (11, 12). Idiotypic determinants are autoantigens recognized by the immune system. The surface nature of idiotypic sequences is evidenced by anti-peptide antibodies interacting with intact immunoglobulin molecules (13-18) and analysis of crystallographic structures of Fab fragments (19,20) and related proteins (21). Herein, a method is described that does not score surface-neutral substitutions in the analysis of evolutionary variability. This approach produces a representation of the shape variability of evolutionarily related proteins. Following the rationale ofJemmerson and Margoliash (3), the variation in the protein surface of cytochrome c and avian lysozyme is used to eval...

“…-----------light-chain prototype sequence from position 42 to 95. This part of the gene includes two cross-reactive idiotypic determinants that were defined by antibodies against synthetic peptides corresponding to the second and third complementarity-determining regions (15,16,27). Fig.…”

Section: Resultsmentioning

confidence: 99%

Genetic basis for the cross-reactive idiotypes on the light chains of human IgM anti-IgG autoantibodies.

Chen¹,

Albrandt²,

Orida³

et al. 1986

Self Cite

The role of immunoglobulin structural genes in the generation of autoantibodies in humans has not been elucidated. Human monoclonal IgM anti-IgG autoantibodies (rheumatoid factors, RFs) from unrelated people often share idiotypic antigens. Antibodies against synthetic peptides have localized two of the shared idiotypic determinants to the second and third complementarity-determining regions of the K light chain. The reported sequences of several human RF light chains are remarkably homologous in these regions. Animal studies have shown that some shared idiotypic antigens represent serological markers for immunoglobulin variable (V)-region genes. Therefore, we hypothesized that human RF light chains derived from a single germ-line gene, designated V -(RF), or from a small family of very closely related genes. In the present experiments, we have isolated and sequenced two human VK germ-line genes that encode K light chains, which are identical or closely related to the light chains of human RF. The data indicate that the shared idiotypic antigens on RF are phenotypic markers for a K V-region gene that is highly conserved in the human population. The results also imply that the light chains of IgM anti-IgG autoantibodies can be encoded by germ-line genes without any somatic mutation.Immune responses are controlled by genes that encode histocompatibility antigens, T-cell receptors for antigens, and immunoglobulins. The inherited structural genes for immunoglobulin light and heavy chains dictate the potential antibody repertoire of any individual. However, immunoglobulin genes also undergo extensive rearrangements and somatic mutations during life (1, 2). Both polymorphisms in inherited immunoglobulin genes as well as somatic changes may therefore influence the ability to form autoantibodies. To dissect the importance of the two factors, one must first isolate potential autoantibody structural genes in their germline configuration. This goal has proved difficult to accomplish in outbred human populations.Idiotypes are antigens in the variable (V) portion of immunoglobulins (3,4). In many instances, idiotypic antigens have been localized at or near the antigen binding site. Immunoglobulins that share idiotypic determinants often are related structurally and may represent the protein products of identical or similar antibody V-region genes (5-8).Kunkel and co-workers first demonstrated that several human monoclonal IgM anti-IgG autoantibodies (rheumatoid factors, RFs) from unrelated subjects shared idiotypic antigens (9). A majority of these monoclonal RFs also had homologous sequences in the K light-chain V regions (10-13). Subsequent experiments with anti-peptide antibodies localized two of the shared idiotypic determinants, also termed cross-reactive idiotypes, to the second and third complementarity-determining regions of the K light chain. After an analysis of multiple RF light chains with a diverse series of anti-idiotypic reagents, we postulated that the cross-reactive idiotypes were markers for a single...