The frequent expansion of a subpopulation of B cells that express RF-associated cross-reactive idiotypes: evidence from analysis of a panel autoreactive monoclonal antibodies

Expression of Y7 Cross‐Reactive Idiotope on Human IgM Molecules

In this paper we report data regarding the IgM Y7 cross-reactive idiotope (CRIo) obtained by analysis of: 1) its V-gene subgroup dependance, 2) the frequency of its expression on human monoclonal IgMs and IgM molecules from normal and pathological sera. Furthermore, comparison of epitopic repertoire and nature of binding of human monoclonal IgMs expressing Y7 CRIo was performed to confirm the natural antibody properties of these molecules. IgM isolated from sera of patient DJ (IgM DJ) which expresses the Y7 idiotope has been classified to VH3/VL2 subgroup. From ten IgMs tested only IgM from patient RD (IgM RD) has been shown to express Y7 idiotope. Y7+ human IgMs bound to ssDNA, lactic acid bacteria, mouse laminin, porcine thyroglobulin and mouse IgG. Higher percentage of the expression of Y7 CRIo was detected in the sera of patients suffering from autoimmune diseases such as lupus, rheumatoid arthritis and psoriasis vulgaris as well as in patients suffering from chronic infections of the lower urinary tract. Antigen binding repertoire and properties of Y7+ monoclonal IgM, frequency of Y7 expression on monoclonal IgMs and its concentration in normal and pathological sera indicate the important biological role of this CRIo within the immune system.

Human monoclonal macroglobulins with antibody activity

Assays for specific antigen-binding activity were performed on sera from 172 patients with monoclonal macroglobulinemia defined by immunofixation electrophoresis. The sera were collected between 1970 and 2002. Mean IgM level was 1,409 mg/dL with a range from 70 to 6,800. Cryoglobulins were identified in 15.3% (26/170 sera: 12 trace, five single component, and nine mixed IgM-IgG). Rheumatoid factor (RF) was detected in 19 of 151 (12.6%) samples with titers ranging from 1:80 to 1:327,680. Among the nine mixed IgM-IgG cryos, eight were RF-positive and six of six displayed positivity for hepatitis C virus. Cold agglutinins (CA) were present in 8.5% (10/117) of sera with anti-I titers between 1:512 and 1:65,536. IgM binding to a series of glycosaminoglycan oligosaccharides, glycolipids, and glycoprotein antigens was found in 75 samples (43%). IgM binding to antigens having known associations to polyneuropathies occurred in 20 patients (12%). Antinuclear antibody (ANA) was documented in 10.7% (18/169) of sera. Anti-DNA activity was absent in all samples tested. Sera from 71% of patients with monoclonal macroglobulinemia in this series exhibited binding to autoantigens. Some of these immune complexes resulted in clinically significant manifestations. Our results suggest that many monoclonal immunoglobulins may be functional antibodies rather than "paraproteins." Characterization of antigen-binding activities may provide insight into the pathogenesis of monoclonal gammopathies.

Long-term kinetics of adult human antibody repertoires

In healthy humans, antibody repertoires change during ontogeny and senescence. The dynamics of antibody repertoires among adults over a longer period of time in one and the same individual has, however, not been extensively studied. In this study we analysed peripheral blood samples from five healthy adults, taken over a period of 10 weeks and once 9 years later. A competitive, quantitative polymerase chain reaction (PCR) was developed to investigate short and long-term variations in VH gene family repertoires. Serum antibody levels to common self and non-self antigens were determined in samples taken at the same time-points as the cell samples to analyse possible correlations between molecular and serological expression profiles. We found a high degree of stability in the VH gene family repertoire over time as well as between individuals with a Caucasian background. A specific change in the usage of primarily the VH3 and VH5 gene families was observed in one individual at one time-point. The deviating pattern resembled the VH gene family utilization pattern observed in naturally activated B lymphocytes. The fluctuations in VH3 and VH5 gene family expression correlated with the presence of rheumatoid factor in serum. We discuss the possible influence of polyclonal, transient stimulation of B cells on VH gene repertoires, as measured in circulating B cells.

Monoclonal antibodies in the prehybridoma era: a brief historical perspective and personal reminiscence

Emil von Behring, an immunologist, received the first Nobel Prize in Physiology or Medicine in 1901 for his studies on serum therapy of diphtheria. Seventeen Nobel Prizes have been awarded to scientists for their work in immunology and related disciplines. E. Metchnikoff and P. Ehrlich were pioneers who became associated with cellular and humoral theories of immunity, respectively. Almroth Wright described opsonins and was a vigorous advocate of vaccine therapy for bacterial diseases. He was an influential scientist and mentor who served as the model for Bernard Shaw's play, The Doctor's Dilemma. Immunochemistry developed through the work of K. Landsteiner, M. Heidelberger, E. Kabat, and many others. At mid-20th century, cell-selection theories of antibody formation championed by N. Jerne and F.M. Burnet shifted the field from a chemical to a biological orientation. Myeloma immunoglobulins, Bence Jones proteins, and monoclonal macroglobulins from patients and mice played a central role in elucidation of normal immunoglobulin structure, genetics, synthesis, and metabolism. By the late 1960s, antibody activity in some human myeloma and Waldenström macroglobulin paraproteins had been documented. Subsequently, other human paraproteins were shown to have antigen-binding properties, principally to auto- or bacterial antigens. The development of hybridoma technology by G. Köhler and C. Milstein revolutionized immunology after 1975. These investigators demonstrated that antibody-producing cells of virtually any desired specificity could be fused with a myeloma cell line, the result being unlimited amounts of homogeneous (monoclonal) antibodies carrying that specificity. Monoclonal antibodies have been shown to have efficacy in cancer therapy, particularly in patients with lymphoma and breast cancer. It is likely that this approach, alone and in combination with other modalities, will prove useful for patients with additional types of malignancies.

Molecular structure of eight human autoreactive monoclonal antibodies

The heavy (H) and light (L) chain V-region sequences of eight human autoreactive immunoglobulin M (IgM) monoclonal antibodies (mAbs: BY-4, BY-7, BY-12, IRM-3, IRM-7, IRM-8, IRM-10 and CDC-1) were determined at the cDNA level. All VH and VL families were identified. Four different VH families were represented, VH3 being the most common as five of the mAbs (BY-7, BY-12, IRM-3, IRM-8 and CDC-1) used genetic elements of this family, whereas VH1, VH2 and VH4 were only present in IRM-7, BY-4 and IRM-10, respectively. BY-4, BY-7, BY-12, IRM-7 and IRM-10 reacted with a variety of self as well as non-self antigens, thus exhibiting polyreactive behaviour. Comparison of the gene segments utilized by these mAbs with their germline counterparts revealed that the gene segments were close to germline configuration. The length of H-CDR3 was found to be relatively long (27-60 nucleotides) among the polyreactive mAbs and the presence of Tyr and Trp residues in this region seems to be of vital importance for polyreactivity. We have analysed the utilization of gene elements and the presence of amino acid residues in regions particularly important for antigen binding, such as CDR. Common molecular features relating to the function of the mAbs are discussed.

Light chain determines the binding property of human anti-dsDNA IgG autoantibodies

We have previously prepared human anti-double-stranded (ds) DNA IgG Fab clones using phage-display technology. Nucleotide sequence analysis of genes of immunoglobulin (Ig) heavy and light chain variable regions in these Fab clones suggested that the DNA-binding activity of the clones depended on light chain usage. To confirm the role of the light chain in antibody binding to DNA, we constructed in the present study's new recombined Fab clones by heavy and light chain shuffling between the original anti-dsDNA Fab clones. Clones constructed by pairing Fdgamma fragments with the light chain from a high DNA-binding clone showed high DNA-binding activities, whereas other constructed clones using light chains from low DNA-binding clones showed low DNA-binding activities. Our results indicate that light chains in anti-dsDNA antibodies can determine the DNA-binding activity of the antibodies. Ig chain shuffling of phage-display antibodies may be useful for investigating the molecular mechanisms for antigen-antibody binding of human autoantibodies.

Rheumatoid factors in primary Sjögren's syndrome (pSS) use diverse VH region genes, the majority of which show no evidence of somatic hypermutation

Rheumatoid factor (RF) is the most common autoantibody found in patients with Sjögren's syndrome (SS). To study the genetic origin and the mechanisms acting behind its generation we have characterized and sequenced the immunoglobulin VH genes used by 10 IgM RF MoAbs derived from peripheral blood of six female patients with pSS. We compared the structure of the RF immunoglobulin VH genes with those obtained previously from rheumatoid arthritis (RA) patients and healthy immunized donors (HID). VH1 and VH4 were each used by four RF clones, one clone was encoded by VH3 family gene and one by VH2 family gene. This distribution frequency was different from that observed in RA, where VH3 was the dominant family, followed by VH1. Eight different germ-line (GL) genes encoded the clones and all of these genes were seen previously in RA and/or HID RF. Five clones rearranged to JH6, four rearranged to JH4 and one to JH5, in contrast to RF from RA and HID, where JH4 was most frequently used. D segment use and CDR3 structure were diverse. Interestingly, three out of four VH4 clones used the GL gene DP-79 that was seen frequently in RA RF. The degree of somatic mutation in the pSS RF was very much lower than seen in RA and HID RF. All the pSS RF clones except three were in or very close to GL configuration. This indicates that there is little role for somatic hypermutation and a germinal centre reaction in the generation of RF from peripheral blood in pSS.