Lack of restriction of T cell receptor beta variable gene usage in cerebrospinal fluid lymphocytes in acute optic neuritis.

OBJECTIVES—There have been many studies reporting restricted patterns of T cell receptor usage in established multiple sclerosis and these have led to clinical trials of immunomodulation directed at deleting clonal T cell populations. The present study aims to test the hypothesis that highly restricted T cell populations are also present in the CSF in the earliest clinical stages of acute demyelinating disease of the CNS. METHODS—T cell receptor Vβ (TCRBV) gene expression was studied in CSF and blood in nine patients with acute optic neuritis within 7 days of onset of symptoms, six patients with an acute relapse of multiple sclerosis, and 13 control subjects. RNA was extracted and cDNA synthesised from unstimulated CSF and blood lymphocytes, and TCRBV gene segments were amplified from the cDNA by polymerase chain reaction (PCR) using 21 family specific primers. PCR products were separated by polyacrylamide gel electrophoresis and detected via a labelled oligonucleotide probe. A semiquantitative analysis of band intensity was performed by laser densitometry. RESULTS—TCRBV mRNA was detected in the CSF of eight of nine patients with optic neuritis, six of six patients with multiple sclerosis, and five of 13 controls, and was closely correlated with the presence of oligoclonal IgG. Usage of a single TCRBV family was demonstrated in two of nine patients with optic neuritis and two of six patients with multiple sclerosis. The number of TCRBV families expressed in the other patients ranged between 5 and 15 (optic neuritis) and 4 and 17 (multiple sclerosis). CONCLUSIONS—There is a relative lack of restriction of TCRBV usage by CSF lymphocytes in the very earliest stages (<7 days) of acute optic neuritis. This may imply either that multiple sclerosis is not a monoclonal disease even at onset, or that the autoimmune response has widened before the disease becomes clinically evident. This may have important consequences for the design of immune therapies in multiple sclerosis. Further studies are required to determine whether the CSF T cell repertoire at presentation has prognostic importance. Longitudinal studies are required to follow the CSF T cell repertoire from the time of presentation and to determine whether it may have prognostic significance.