PHENOTYPES AND INVARIANT ALPHA-BETA TCR EXPRESSION OF PERIPHERAL V-ALPHA-14-CELLS( NK T)

A novel subset of peripheral T cells, peripheral NK T cells, is found to be a major population comprising 5% of splenic T and 40% of bone ma rrow T cells. The majority of peripheral NK T cells are characterized by the expression of an invariant TCR-alpha encoded by V alpha 14/J al pha 281 with a one nucleotide N region. Moreover, a specific reduction of V alpha 14(+) NK T cells has been demonstrated to be tightly assoc iated with various autoimmune diseases, indicating their decisive role in autoimmune disease development. In this study, we investigated the phenotypes of peripheral V alpha 14(+) NK T cells and their TCR-beta repertoire. Peripheral V alpha 14(+) NK T cells, comprise two populati ons, i.e., small and large sized cells, at an equal frequency, belonge d to the CD4(-)CD8(-) fraction, and are heat stable antigen(bright), m acrophage-1(bright), B220(bright), CD45RB(dim), and Mel-14(dim), but C D5(-), distinct from thymic NK T cells. TCR-beta analysis clearly show ed that peripheral V alpha 14(+) NK T cells utilized two to three domi nant invariant TCR-beta, such as V beta 8.2D beta J beta 2.5/V beta 7D beta J beta 2.1 in the spleen and liver, V beta 8.2D beta J beta 2.5/ V beta 8.3D beta J beta 2.2/V beta 7D beta J beta 2.6 in the bone marr ow, and V beta 7D beta J beta 2.1/V beta 3D beta J beta 1.2 in intesti nal intraepithelial lymphocytes. judging from the unusual surface phen otypes, such as heat stable antigen, macrophage-1, B220, CD45RB(dim), and Mel-14(dim), which are known to be T cell activation markers, peri pheral V alpha 14(+) NK T cells may always be activated under physiolo gic conditions, resulting in the oligoclonal expansion of V alpha 14() NK T cells with different invariant TCR-beta in different peripheral organs. The unique features of V alpha 14(+) NK T cells are discussed .