GAMMA-DELTA-T-CELL RECEPTOR ANALYSIS SUPPORTS A ROLE FOR HSP-70 SELECTION OF LYMPHOCYTES IN MULTIPLE-SCLEROSIS LESIONS

Background: Interactions between gamma delta T cells and heat shock pr oteins (HSP) have been proposed as contributing factors in a number of diseases of possible autoimmune etiology but definitive evidence to s upport this hypothesis has been lacking. Ln multiple sclerosis (MS), a chronic inflammatory neurologic disease, HSP and gamma delta T cells are known to colocalize in brain lesions. Analysis of T cell receptor (TCR) gene usage in these lesions has detected evidence of clonality w ithin both the V delta 2-J delta 1 and V delta 2-J delta 3 populations of gamma delta T cells. In our own studies, using direct sequence ana lysis, a dominant V delta 2-J delta 3 TCR sequence was found in 9 MS b rain samples, suggesting a response to a common antigen. In this repor t we have examined gamma Delta T cell receptor gene usage in MS periph eral blood T cell lines selected for reactivity to HSP 70. Materials a nd Methods: TCR rearrangement patterns for V delta 2-J delta 1 and V d elta 2-J delta 3 were studied using the polymerase chain reaction (PCR ) and a direct sequencing technique in populations of peripheral blood mononuclear cells (PBMC) cultured with Mycobacterium tuberculosis (M. tuberculosis) purified protein derivative (PPD) and then selected for reactivity to a 70-kD heat shock protein (HSP70). Cells were obtained from healthy donors, patients with MS, and patients with tuberculosis (TB). PCR products were subjected to direct sequence analysis to look for evidence of clonality within these T cell lines and to define the sequence of the V-D-J (CDR3) region of the TCR. Results: In freshly i solated PBMC, both V delta 2-J delta 1 and V delta 2-J delta 3 gene re arrangement patterns were detected, whereas in HSP7O(+) T cell lines t he predominant delta chain rearrangement pattern was V delta 2-J delta 3. Direct sequence analyses indicated that in cells reactive with HSP 7O the V delta 2-J delta 3 sequences were usually oligoclonal and used D delta 3 exclusively. In four of four MS and two of three TB patient s, the oligoclonal sequences in the HSP7O(+) T cell lines were identic al to one another and to a dominant sequence previously detected in MS brain lesions. Ln two of three HSP7O(+) T cell lines from healthy con trols, the oligoclonal sequences differed from those found in both gro ups of patients but were identical to one another except for a small r egion of heterogeneity in the second N region In contrast, in freshly isolated PBMC or in PPD(+)HSP70(-) T cell lines, the V delta 2-J delta 3 gene rearrangement patterns were usually polyclonal and dominant se quences were rarely identified. Conclusions: These results support the conclusion that a subpopulation of y delta T cells in MS lesions are responding to HSP 70 and that non-CNS-specific antigens contribute to the pathogenesis of MS.