Dornmair Lab – Disease-relevant lymphocytes

We are investigating properties and target antigens of disease-relevant B- and T-cells of patients with multiple sclerosis, encephalitis, narcolepsy, psoriasis, and of other disease conditions. Over the years we have established several techniques that now allow us to distinguish disease-relevant cells from bystander cells and to identify the target antigens of antibodies and CD8+ T cells. To this end, we analyze the lymphocyte repertoire by mRNAseq and isolate disease-relevant cells by flow cytometry and 10X technology from body fluids or by laser microdissection from tissue. From single putatively disease-relevant B- and T-cells we then identify matching chains of antibodies or T cell receptors (TCR), clone their heavy and light or α- and β-chains, and functionally express the antibodies or TCRs in vitro.

We analyze the antigens of antibodies by conventional biochemical methods, and found that “oligoclonal band” antibodies, which are important diagnostic markers in multiple sclerosis and other inflammatory neurological diseases, often recognize debris released from dead cells. By contrast, antibodies from patients with encephalitis may recognize surface proteins on cells in the brain and may thus directly contribute to clinical symptoms.

Due to the very low affinities of TCRs to their target antigens (i.e. MHC/peptide complexes), biochemical methods are not suited for T cell antigen identification. Therefore, we have developed an unbiased technology to identify their as yet unknown antigens. This method is based on plasmid-encoded combinatorial peptide libraries which can be loaded onto class I MHC molecules and an extremely sensitive screening system, which uses fluorescent reporter molecules that are expressed upon T cell activation. This technology may be applied to all conditions where CD8+ T cells are relevant, i.e. to many autoimmune, tumor and infectious diseases.