T-CELL RECEPTOR V-BETA-5 AND V-BETA-17 CLONAL DIVERSITY IN CEREBROSPINAL-FLUID AND PERIPHERAL-BLOOD LYMPHOCYTES OF MULTIPLE-SCLEROSIS PATIENTS

To better characterize the cellular immune response taking place in th e MS central nervous system, we investigated the blood and CSF T cell receptor (TCR) V beta 5 and V beta 17 repertoire in HLA-typed patients with recently diagnosed MS or other neurological diseases (OND). Usin g a RT-PCR based technique, we analysed directly ex vivo the CDR3 size of TCR beta chains utilizing V beta 5 (eight patients with MS and one with OND) or V beta 17 (eight patients with MS and six with OND) gene segments on paired blood-CSF samples. Globally the analysis of V beta 5-J beta and V beta 17-J beta repertoire showed a less diverse patter n in the CSF samples than in the corresponding peripheral blood lympho cytes both in MS and in OND patients. However, we did not detect any r ecurrent clonal expansion within the V beta 5(+) T cells in MS patient s, underlining the potential limits of V beta 5-based immunotherapy in MS. We found an expanded T cell population using the same V beta 17-J beta 1.6 combination with identical CDR3 length in the CSF of three M S patients and none of the control patients. These results suggest sel ective expansion of T cells expressing this segment gene in the MS cen tral nervous system.