Gene transfer of inflammation-inducible hIL-10 prevents reactivation of SCW arthritis. (a) Inhibition of leukocytosis. On day –42, animals were IA injected with PG-APS in both ankle joints. On day –1, animals were injected in both ankle joints with the indicated Ad, as for Figure 2b. In this experiment there were 12 animals per group on day –1. On day 0, reactivation was induced by intravenous injection of PG-APS. On days 0, 1, 2, 3, 4, and 6 after reactivation, two animals from each group were euthanized, and ankle joints were perfused for determining the numbers of infiltrating white blood cells (WBCs) (21). The time course of leukocytosis is shown. Each bar shows the mean ± SEM of measurements from four joints. Data representative of two experiments are shown. (b) Inhibition of joint swelling. In parallel to measuring leukocytosis, inflammation was assessed by measuring joint swelling. As animals in each group were euthanized in order to obtain joint lavages, the data points represent a diminishing number of joints. Swelling was calculated as (d_i) – (d₀), where (d_i) and (d₀) are mean joint diameters at day i and day 0. Error bars represent SEM. P values for comparisons between groups in a and b were calculated using the unpaired one-tailed Student t test. Data on inhibition of joint swelling in other experiments are presented in Table 1.