Analysis of the T-cell Receptor Valpha Repertoire and Cytokine Gene Expression in Sjögren's Syndrome

The antigen receptor diversity of pathogenic T cells in Sjögren's syndrome (SS) may have important implications in the development of the disease; cytokines from these cells and other sources also play a role in the pathogenesis of this disease. Using a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) technique, we have attempted to correlate the presence of restriction in the T-cell receptor (TCR) repertoire with cytokine profiles. We have analysed TCR V alpha family usage, and the expression of interleukin-1alpha (IL-1alpha), IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-13, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha), in labial biopsies from 12 patients with SS and compared these with samples from three patients with chronic sialadenitis (CS). Only one of the SS biopsies showed evidence of V alpha restriction (three out of 18 gene families). Apart from this, expression patterns were similar in both patient groups. Four of the 12 SS samples demonstrated a 'limited heterogeneity' of the V alpha repertoire with 3-4 families predominantly expressed, in particular V alpha1 and V alpha3. Peripheral blood lymphocytes were unrestricted. The cytokine profiles of the SS and CS biopsies were generally similar. However both IFN-gamma and IL-1alpha were absent from CS, but present in SS samples. The expression of IFN-gamma in the majority of the samples, together with a lack of IL-4 and IL-13 mRNA, suggests the predominance of a Th1 response in SS. There was no clear association between the repertoire of V alpha genes expressed and the cytokine profile observed. However, the V alpha restriction in one SS sample did correspond with a limited diversity of cytokines detected.