Analysis of immunoglobulin and T cell receptor gene rearrangements in the thymus of myasthenia gravis patients.
The thymus is an important site of sensitization of autoreactive B and T lymphocytes in myasthenia gravis (MG). We have investigated clonal diversity of B or T cells in the thymus of patients with MG by Southern blot experiments using probes specific for immunoglobulin heavy (IgH) and light chain (IgL) genes and for T cell receptor (TCR) beta- and gamma-chain genes. This method allows to detect individual clones of B or T cells if they represent at least 1% of the total cell population. We investigated thymus glands from 14 patients who underwent thymectomy. Single rearranged fragments could be demonstrated with a TCR gamma-specific probe in DNAs from both normal donors and MG patients. TCR beta gene rearrangements occurred mainly in the C beta 1 region. However, single rearranged bands could not be detected with either TCR beta, JH or with J kappa specific probes. Thus any single autoimmune B and T cell clone present in the myasthenic thymus represents presumably less than 1% of all thymocytes.
I. Medizinische Klinik, University of Cologne, Köln, F.R.G.
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Tesch
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Hohlfeld
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Toyka
D015139:Blotting, Southern; D004247:DNA; D015342:DNA Probes; D015321:Gene Rearrangement; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics*; D009157:Myasthenia Gravis / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D011971:Receptors, Immunologic / Q000235:genetics*; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000503:physiopathology*
D015342:DNA Probes; D007136:Immunoglobulins; D011971:Receptors, Immunologic; D004247:DNA