Figure 1.

Adoptively transferred naïve CD4 T cells cause GVHD with more rapid incidence with increased cell number transferred. (a) the graph shows incidence of GVH (as % affected) in adoptive hosts of FACS sorted naïve CD4⁺ CD44^lo CD25⁻ cells (1 × 10⁶ cells/host, n = 18 hosts, solid line; 2 × 10⁶cells/host, n = 8 hosts, dashed line) or sorted memory CD4⁺ CD44^hi CD25⁻ cells (1 × 10⁶ cells/host, n = 8 hosts, dotted line) from C57Bl/6 CD45.1 mice. Recipient mice with no signs of disease, i.e. a severity score of 0 are defined as ‘unaffected’. Mice with severe disease or in obvious distress, typically correlating to a score of 3 or greater, were culled. All host mice were culled within 47 days of cell transfer due to severe disease. (b) Disease severity scores for each host were assigned using a scale of 0 to a maximum of 4 as detailed in Materials and methods. Naïve cells (1 × 10⁶), solid line; naïve cells (2 × 10⁶), dashed line; memory cells (1 × 10⁶), dotted line. For each observed symptom, the corresponding scores were added. (c) Recovery of CD4 T cells in early stages of disease following transfer of 1 × 10⁶ naïve cells, i.e. from hosts with a clinical score less than 1·5 (white bars) and of CD4 T cells at a late stage of disease, i.e. from hosts with a clinical score more than 2 (black bars). Cell recovery was calculated by measuring total cell counts per organ and using flow cytometry to determine the proportion of CD4⁺ TCR⁺ cells within each organ. The data shown is representative of three independent experiments, with between three and five mice/group. (d) Ex vivo spleens taken from recipients following transfer of 1 × 10⁶ naïve cells, one at severity <1·5 and one at severity >2. Photo representative of three independent experiments, with three to five mice in each group.