We study how B cells are selected and how antibody responses develop and persist in human disease. Our research covers immunoglobulin repertoires, antibody isotypes and allotypes, and genetic variation in immune receptor loci.

In multiple sclerosis, we investigate B-cell responses involved in inflammation within the central nervous system and the production of oligoclonal IgG. We also study the role of Epstein–Barr virus (EBV) and how B-cell-directed therapies affect these immune responses. We analyse samples from cerebrospinal fluid, blood, and cervical lymph nodes.

Our methods include single-cell RNA sequencing, paired B-cell receptor reconstruction, Oxford Nanopore long-read sequencing, spectral flow cytometry, and proteomics. We also develop bioinformatic methods to analyse these data.

We are based at the Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo. We work closely with researchers and clinicians at Akershus University Hospital and Oslo University Hospital, and with other research groups in Norway and abroad.

Projects

  • B cells and immunoglobulins in multiple sclerosis
  • Immunoglobulin genetics and antibody repertoires
  • B cells in cervical lymph nodes and other secondary lymphoid tissues in MS
  • T follicular helper cells and B-cell help in MS

Representative publications

Seyedraoufi S, Gornitzka MB, Lossius A. GATHeR: graph-based accurate tool for immunoglobulin heavy- and light-chain reconstruction. Nat Commun. 2026 Jun 10. https//doi.org/10.1038/s41467-026-74272-w

Gornitzka MB, Røsjø E, Jana U, Ford EE, Tourancheau A, Lees WD, Vanwinkle Z, Smith ML, Watson CT, Lossius A. Ultra-long sequencing for contiguous haplotype resolution of the human immunoglobulin heavy-chain locus. Genome Research. 2025. https://doi.org/10.1101/gr.280400.125

Polak J, Wagnerberger JH, Torsetnes SB, Lindeman I, Høglund RA, Vartdal F, Sollid LM, Lossius A. Single-cell transcriptomics combined with proteomics of intrathecal IgG reveal transcriptional heterogeneity of oligoclonal IgG-secreting cells in multiple sclerosis. Frontiers in Cellular Neuroscience. 2023. https://doi.org/10.3389/fncel.2023.1189709

Lindeman I, Polak J, Qiao SW, Holmøy T, Høglund RA, Vartdal F, Berg-Hansen P, Sollid LM, Lossius A. Stereotyped B-cell responses are linked to IgG constant region polymorphisms in multiple sclerosis. European Journal of Immunology. 2022. https://doi.org/10.1002/eji.202149576

Høglund RA, Bremel RD, Homan EJ, Torsetnes SB, Lossius A*, Holmøy T*. CD4+ T Cells in the Blood of MS Patients Respond to Predicted Epitopes From B cell Receptors Found in Spinal Fluid. Frontiers in Immunology. 2020; 11: 598. *Shared senior authorship. https://doi.org/10.3389/fimmu.2020.00598

Tomescu-Baciu A, Johansen JN, Holmøy T, Greiff V, Stensland M, de Souza GA, Vartdal F, Lossius A. Persistence of intrathecal oligoclonal B cells and IgG in multiple sclerosis. Journal of Neuroimmunology. 2019; 333: 576966. https://doi.org/10.1016/j.jneuroim.2019.576966

Tomescu-Baciu A, Vartdal F, Holmøy T, Vedeler CA, Lossius A. G1m1 predominance of intrathecal virus-specific antibodies in multiple sclerosis. Annals of Clinical and Translational Neurology. 2018; 5(10): 1303-1309. https://doi.org/10.1002/acn3.642

Lossius A, Tomescu-Baciu A, Holmøy T, Vedeler CA, Røsjø E, Lorentzen ÅR, Casetta I, Vartdal F. Selective intrathecal enrichment of G1m1-positive B cells in multiple sclerosis. Annals of Clinical and Translational Neurology. 2017; 4(10):756-761. https://doi.org/10.1002/acn3.451