T-CELL HETEROGENEITY IN MUSCLE LESIONS OF INCLUSION-BODY MYOSITIS

In the muscle lesions of inclusion body myositis (IBM), two population s of T cells can morphologically be distinguished, T cells that invade muscle fibers and T cells that remain in interstitial areas. Using co mbined immunohistochemistry and RT-PCR, we analysed the TCR expressed by these distinct T cell populations. In three of eight IBM muscle spe cimens, the autoinvasive T cells were stained with one of the availabl e mAbs: anti-V beta 5.3 in patient 1, anti-V beta 5.2 in patient 2, an d anti-V beta 3 in patient 3. The corresponding TCR VP mRNAs were ampl ified by RT-PCR and the PCR products were cloned and sequenced. In all three specimens, the TCRs expressed by the autoinvasive T cells were clonally restricted. Furthermore, in patient 1 two different mAbs labe lled two distinct populations of T cells: an autoaggressive population of CD8 + V beta 5.3 + cells that invaded muscle fibers and a noninvas ive interstitial population of CD8-V beta 5.1 + cells. TCR sequence an alysis revealed that the noninvasive V beta 5.1 + T cells were clonall y diverse, whereas the autoinvasive V beta 5.3 + T cells were clonally restricted. (C) 1998 Elsevier Science B.V.