Rat NKR-P1 + CD3 + T cells: Selective proliferation in interleukin-2, diverse T-cell-receptor-Vβ repertoire and polarized interferon-γ expression

Abstract

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 + CD 8- phenotype, and upon anti-CD3 stimulation secrete large amounts of interleukin-4 (IL-4) and interferon-γ (IFN-γ). NK T cells may be the primary source of 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 responses, and may consequently affect susceptibility to autoimmune diseases associated with a skewed Th phenotype. We show that rat NK T cells selectively proliferate to IL-2, and sse this fact to analyse cytokine production by NK T cells in two rat strains differentially susceptible to Th1- or Th2-type autoimmune diseases. Analysis by reverse transcription-polymerase chain reaction revealed that, in contrast to mouse, rat NK T cells secrete exclusively IFN-γ and not IL-4 after anti- CD3 stimulation, and use a wider TCR-Vβ repertoire, suggesting that rat NK T cells are not essential for the development of Th2-type CD4 + T-cell responses.