RAT NKR-P1(-CELLS - SELECTIVE PROLIFERATION IN INTERLEUKIN-2, DIVERSET-CELL-RECEPTOR-V-BETA REPERTOIRE AND POLARIZED INTERFERON-GAMMA EXPRESSION() CD3(+) T)

Cells expressing markers of both natural killer and T lymphocytes (NK T cells) in humans and mice express a restricted T-cell receptor (TCR) repertoire, are of CD4(-) CD8(-) or CD4(+) CD8(-) phenotype, and upon anti-CD3 stimulation secrete large amounts of interleukin-4 (IL-4) an d interferon-gamma (IFN-gamma). NK T cells may be the primary source o f IL-4-promoting T helper type 2 (Th2) responses and/or they might be involved in regulating the balance between Th1- and Th2-type immune re sponses, and may consequently affect susceptibility to autoimmune dise ases associated with a skewed Th phenotype. We show that rat NK T cell s selectively proliferate to IL-2, and use this fact to analyse cytoki ne production by NK T cells in two rat strains differentially suscepti ble to Th1- or Th2-type autoimmune diseases. Analysis by reverse trans cription-polymerase chain reaction revealed that, in contrast to mouse , rat NK T cells secrete exclusively IFN-gamma and not IL-4 after anti -CD3 stimulation, and use a wider TCR-VP repertoire, suggesting that r at NK T cells are not essential for the development of Th2-type CD4(+) T-cell responses.