Abstract: Objective To examine the relationship between CCT5, γδ T cell and autoimmune diseases. Methods Recombinant CCT5 protein was cloned, expressed and purified in E.coli. Three peptides of CCT5 protein was used to prepare for anti-CCT5 monoclonal antibodies. Purified CCT5 protein was used to expand γδ T cells from peripheral blood mononuclear cells (PBMC). Plasma levels of CCT5 in healthy donors, patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) were detected by ELISA assays. The correlation analysis between plasma CCT5 concentration and the percentage of different subtypes of γδ T cells measured by flow cytometry was made. Results The CCT5 gene was amplified by PCR and the length of the target fragment was 1 750 bp. The expressed 65ku CCT5 protein was purified and validated by SDS-PAGE. Two paired monoclonal anti-CCT5 antibodies were screened to detect CCT5 protein in plasma. Immobilized recombinant CCT5 protein was able to induce specific significant amplification of peripheral γδ T cells. Correlation analysis of 10 healthy donors indicated significant correlation between the plasma CCT5 concentration and the proportion of Vγ9 and Vδ2 γδ T cells. The plasma CCT5 concentration was significantly decreased in autoimmune diseases patients, including RA and SLE. Conclusion These data suggest that CCT5 could be a novel Vγ9δ2 γδ T cell-related factor in autoimmune diseases, which deepen our understanding of Vγ9δ2 γδ T cell function in autoimmune diseases.

Key words: CCT5, autoimmune diseases, γδ T cells, autoantigen