Detection of Clonally Expanded T-Cells by RT-PCR-SSCP and Nucleotide Sequencing of T-Cell Receptor -CDR3 Regions

T-cell clonal expansion has been detected in the peripheral blood or the disease-affected sites in patients who suffer from various disease states such as infections, autoimmune diseases, malignancy, and post-transplantation complications (1 –7 ). Since T-cells begin to proliferate clonally when they recognize their specific antigens, the clonal T-cell expansion is considered to be a result of an antigen-specific immune response. For analysis of such antigen-specific T-cells, it is common to use their specific antigens if they are known. However, there are many diseases, such as rheumatoid arthritis, in which the pathogenic antigens are unknown. In these circumstances, the detection of clonally expanded T-cells is an effective method to evaluate whether antigen-specific immune responses are involved, since few clonally expanded T-cells are detected in healthy individuals (4 ). In addition, the characterization of any clonally expanded T-cells that are detected would further promote the understanding of the disease mechanisms.