Phytol Inhibits Arthritogenic T Cells In Vivo

<div><p>(A) Phytol (Ph) prevents adoptive transfer of arthritis when injected into the recipient DA.<i>Ncf1</i>^DA rat before onset. Phytol was injected (200 μl SC) in the recipient 3 d or 3 h before transfer of arthritogenic T cells from pristane injected DA.<i>Ncf1</i>^DA rats (control, <i>n</i> = 8; phytol, <i>n</i> = 16).</p> <p>(B) Phytol ameliorates arthritis also when injected in recipient DA.<i>Ncf1</i>^DA rats after disease onset. Phytol was injected (200 μl SC) in the recipient rats days 5 and 8 after transfer of arthritogenic T cells (control <i>n</i> = 7 and phytol <i>n</i> = 8).</p> <p>(C) Phytol inhibits arthritogenic T cells when injected in the donor DA.<i>Ncf1</i>^DA rat. Spleen cells from phytol treated (500 μl SC day −5) rats were taken day 10 after pristane injection, transferred into naïve DA.<i>Ncf1</i>^DA rats and the effect of phytol on the development of arthritogenic T cells were followed (<i>n</i> = 8).</p> <p>(D, E) Phytol has a rapid inhibitory effect on arthritogenic T cells. The time-point for the effect of phytol was titrated by administration of phytol (500 μl SC) on different days after pristane injection (day 0). Day 10 after pristane, donor spleens (DA.<i>Ncf1</i>^DA) were taken and analyzed for oxidative burst of granulocytes (<i>n</i> = 3) (D) and the cells transferred into naïve DA.<i>Ncf1</i>^DA recipient rats. The rats were then monitored for arthritis symptoms (E). Cells from rats treated day 0 and control rats were also mixed (50:50) to investigate a possible dominating effect of phytol treatment (control [Cnt], <i>n</i> = 6; phytol, <i>n</i> = 5; and mix, <i>n</i> = 3).</p> <p>(F) Phytol does not induce acute cell death. Percentage of apoptotic (Annexin V+ and PI−) and necrotic (Annexin V+ and PI+) CD4⁺ cells ex vivo 3 h after phytol (<i>n</i> = 5).</p> <p>*<i>p</i> < 0.05, **<i>p</i> < 0.01, ***<i>p</i> < 0.001.</p>