Restricted usage of T-cell receptor Valpha-Vbeta genes in infiltrating cells in the aortic tissue of a patient with atherosclerotic aortic aneurysm.

We report a rare case of an atherosclerotic aortic aneurysm with lymphocyte infiltration in which T-cell receptor (TCR) Valpha as well as Vbeta gene usage was restricted. Immunohistochemical studies showed that the infiltrating cells mainly consisted of macrophages, natural killer (NK) cells, cytotoxic T lymphocytes (CTLs) and T-helper (Th) cells, and that there were almost no infiltrating delta T lymphocytes, and human leukocyte antigen (HLA) class I and 65-kD heat-shock protein (HSP-65) was not strongly expressed in the aortic tissue. Although the immunohistochemical data were consistent with an ordinary atherosclerotic aortic aneurysm, in which TCR Valpha-Vbeta gene usage is known to be polyclonal, the restricted TCR gene usage suggests that a certain autoimmune mechanism was involved in the pathogenesis of this case similar to Takayasu's arteritis, in which massive infiltration of delta T lymphocytes and strong expression of HSP-65 in the aortic tissue are characteristic.