Cell transfer: prevention of arthritis. Tetramer+ T cells from draining lymph nodes were collected from DR1Tg mice immunized 10 days earlier with A12/CFA. DR1 mice (n = 3) were infused with 2 × 105 cells of either tetramer+ or tetramer-, A12-primed CD4+ T cells. All recipients were immunized with CII/CFA on the day of the cell transfer and observed for arthritis. (A) Mean severity scores over time. As indicated, only the tetramer+ A12-immune cells could prevent collagen-induced arthritis (final severity scores comparing square versus triangle of 1.3 ± 2.5 versus 5.4 ± 3.2; P ≤ 0.01. The cell-transfer experiments have been repeated with both unfractionated cells and VB8+, VB14+ purified T cells from A12-immunized lymph nodes with similar results. Suppression of established arthritis (B). Inguinal lymph node cells from A12-immunized DR1 mice were fractionated into a VB8, VB14+ population and a VB8, VB14- population. DR1 mice (n = 10) were immunized with CII/CFA and observed for the development of arthritis. On day 23 after immunization, when arthritis was established, each mouse was infused intravenously with 5 × 105 cells of either VB8, VB14+ T cells (enriched for 7.5 × 104 tetramer+ cells) or VB8, VB14- T cells. (B) Mean severity scores over time. As shown, only the VB8, VB14+ A12-immune T cells could suppress active arthritis in the collagen-induced arthritis model (final severity scores comparing (triangle versus circle) of 1.5 ± 1.0 versus 5.6 ± 1.6; P ≤ 0.03). Data shown are representative of three separate experiments.