Autoimmune diseases show high diversity in the affected organs, clinical manifestations and disease dynamics. Yet they all share common features, such as the ectopic germinal centers found in many affected tissues. Lineage trees depict the diversification, via somatic hypermutation (SHM), of immunoglobulin variable-region (IGV) genes. We previously developed an algorithm for quantifying the graphical properties of IGV gene lineage trees, allowing evaluation of the dynamical interplay between SHM and antigen-driven selection in different lymphoid tissues, species, and disease situations. Here, we apply this method to ectopic GC B cell clones from patients with Myasthenia Gravis, Rheumatoid Arthritis, and Sjögren's Syndrome, using data scaling to minimize the effects of the large variability due to methodological differences between groups. Autoimmune trees were found to be significantly larger relative to normal controls. In contrast, comparison of the measurements for tree branching indicated that similar selection pressure operates on autoimmune and normal control clones.
Bibliographical noteFunding Information:
The authors are indebted to Osnat Steiman for editing the manuscript. The work was part of Avital Steiman-Shimony’s studies towards an MSc degree in Bar-Ilan University, and was supported in parts by the following Grants: the Israel Science Foundation Grants number 759/01-1 and 546, an Israel Cancer Research Fund project Grant, a Systems Biology prize Grant from Teva Pharmaceuticals, a Human Frontiers Science Program Young Investigator Grant, and a Swedish Foundation for Strategic Research Grant funding the Strategic Research Center for studies on Integrative Recognition in the Immune System (IRIS), Karolinska Institute, Stockholm, Sweden (to RM); a BBSRC Science of Ageing initiative Grant (to DDW); Grants from the EC Marie Curie Research Fellowship (the SS work), and The Wellcome Trust (the MG work), to DIS; and a Hematological Malignancies Research Fund, Mayo Clinic Grant (to RSA).
- Germinal centers
- Myasthenia Gravis (MG)
- Rheumatoid Arthritis (RA)
- Sjögren's Syndrome (SS)
- Somatic hypermutation