Gamma delta T cell receptor repertoire in brain lesions of patients with multiple sclerosis

The identification of activated T cells in the brains of patients with multiple sclerosis (MS) suggests that these cells are critical in the pathogenesis of this disease. Recently we have used the PCR method to analyse rearrangements of V alpha and V beta genes of the T cell receptor (TCR) in samples of MS and control brains. The results of these studies showed that TCR V gene usage in MS brains may be restricted and in particular that V beta genes may be preferentially rearranged in certain HLA haplotypes associated with susceptibility to MS. In view of the recent evidence that T lymphocytes bearing the gamma delta chains may have autoreactive potential, we have assessed whether or not such TCR-bearing lymphocytes were also present in chronic MS lesions. TCR V gamma and V delta were analysed by the PCR method using a panel of V gamma and V delta primers paired with C gamma or C delta primers in 12 MS brains, as well as in brain samples of ten normal post-mortem cases and three neurological controls. TCR V gamma-C gamma and V delta-C delta rearrangements were confirmed using Southern blotting and hybridisation of the PCR products with specific C gamma and C delta probes. Only one to four rearranged TCR V gamma and V delta transcripts were detected in each of the 23 brain samples obtained from 12 MS patients, with the majority of gamma delta T cells expressing the V gamma 2 and V delta 2 chains. In marked contrast, V gamma and V delta transcripts could only be found in one of the ten non-neurological control brains analysed. To assess the clonality of V gamma 2 and V delta 2 T cell receptor chains in the brain samples of MS patients, we have sequenced the junctional regions of the TCR V gamma-N-J gamma-C gamma and V delta-N-D delta-N-J delta-C delta segments amplified from brain tissues, CSF and spleens of two MS patients and from the spleen of two control subjects. The sequence analysis obtained so far shows no compelling evidence of an MS specific expansion of one or more clones expressing particular types of gamma delta T cell receptors. In contrast, a clonal expansion of a different population of TCR gamma delta-bearing T cells was found in the spleen of both an MS patient and one of the control individuals.(ABSTRACT TRUNCATED AT 400 WORDS)