Overall, we found evidence for antigen-driven positive selection in these cells. and selection pressure, then expressed as the native mAbs, or mutant mAbs lacking the acN-glyc for specificity testing. Protein modeling was used to demonstrate how even acN-glycs outside of the complementarity-determining region (CDR) could participate in, or inhibit, antigen binding. Results V-region sequence analyses revealed clonal expansions and evidence for secondary light chain editing and allelic inclusion not previously reported in SS. We found increased acN-glycs in the sequences from SS patients and that acN-glycs were associated with increased replacement mutations and lowered selection pressure. We also identified a clonal set of polyreactive mAbs with differential FWR1 acN-glycs and demonstrated that removal of the acN-glyc could nearly abolish binding to the autoantigens. Conclusion Our findings support an alternative mechanism involving V-region N-glycosylation for the selection and proliferation of some autoreactive B cells in SS patients. Sj?grens syndrome (SS) is a systemic, chronic autoimmune disease that is characterized by lymphocytic infiltration of the exocrine glands, inflammation, tissue damage, and secretory dysfunction. The lacrimal and salivary glands are typically affected, resulting in dry eyes (keratoconjuntivitis sicca) and dry mouth (xerosomia), but patients can also ASC-J9 present with extraglandular complications, or overlapping autoimmune diseases. (1C5). In ASC-J9 addition, SS patients have an increased risk of progression to various non-Hodgkin lymphomas (NHL) resulting in significant morbidity (6). There is evidence for chronic immune cell stimulation by bacteria in the development of NHLs not associated with SS (7C9). This mechanism was demonstrated, where and lectins bound to and activated B cells via B cell receptor variable region (V-region) glycans (10). In SS NHL there is also evidence for a bacterial etiology with the regression of a parotid mucosa-associated lymphoid tissue (MALT) lymphoma after the clearing of an infection (11). It is known that dysregulation of both innate and adaptive immunity contributes to the etiology of SS and its complications; however, the pathophysiology of SS as well as Sj?grens-associated lymphoma is largely unknown. B cells play a role in the pathogenesis of SS as evidenced by the presence of autoantigen-specific memory B cells (12, 13) and the incidence of autoantibodies to Ro/SSA (Ro52 and Ro60) and La/SSB (14). Much evidence supports antigen-driven production of autoantibodies within the salivary glands (13, 15, 16). Ig V-region sequence analysis enables the identification of clonally expanded cells, which is strong evidence for antigen-driven B cell activation and proliferation. Antigen-driven activation can also be determined empirically by selection pressure analyses of V-region sequences where the observed frequency of non-synonymous (replacement) mutations is compared to their expected frequency in a state of no selection. When the frequency of replacement mutations is greater than expected, the Ig is considered to have undergone positive selection, and when the frequency is less than expected, negative selection is indicated. Typical antigen-driven activation results in positive selection in the CDR regions, which ASC-J9 directly interact with the antigen, and negative selection in the framework regions (FWRs), which are important for structural integrity. Selective pressure patterns contrary to this model indicate non-specific activation. Somatic Rabbit polyclonal to Fyn.Fyn a tyrosine kinase of the Src family.Implicated in the control of cell growth.Plays a role in the regulation of intracellular calcium levels.Required in brain development and mature brain function with important roles in the regulation of axon growth, axon guidance, and neurite extension.Blocks axon outgrowth and attraction induced by NTN1 by phosphorylating its receptor DDC.Associates with the p85 subunit of phosphatidylinositol 3-kinase and interacts with the fyn-binding protein.Three alternatively spliced isoforms have been described.Isoform 2 shows a greater ability to mobilize cytoplasmic calcium than isoform 1.Induced expression aids in cellular transformation and xenograft metastasis. hypermutations (SHMs) leading to amino acid replacements can also give rise to post-translational modifications by the introduction of N-linked glycosylation (N-glyc) motifs. This results in SHM-acquired N-glycs (acN-glyc) of the antibody at these sites, and may have implications in immune responses or disease states. Ig V-region acN-glycs have been reported in SS parotid B cells (17) and are strongly correlated to follicular lymphoma (18, 19), a disease increased 4-fold in SS patients (20). Single Ig V-region acN-glycs introduced by SHM have been demonstrated to strengthen (21), weaken, or abolish binding for self or foreign antigens (22). Conversely, bacterial or innate immune system lectins can bind V-region acN-glycs, causing activation of B cells in an antigen-independent fashion (10, 23). Therefore, analyses of acN-glyc motifs may give clues to antibody-antigen interactions, tolerance mechanisms, and nonspecific modes of B-cell activation that may drive proliferation of B cells in SS. We hypothesized that acN-glyc motifs in the V-regions of IgG ASCs isolated from the labial salivary glands of SS patients and non-SS patients with dry mouth/eye symptoms (sicca) controls may provide opportunities for antigen-independent proliferation of autoreactive B cells and antibody production in the salivary glands of SS patients. Our findings support this hypothesis, suggesting an alternative means for B cell selection and proliferation of some autoreactive B cells seen in SS patients. Patients and Methods Human Subject Sample Collection and Evaluation Studies were approved by the Oklahoma Medical Research Foundation (OMRF) and University of Oklahoma Health Sciences Center.