Passive transfer of ANCA-rich immunoglobulin enhances microvascular responses in naive WKY rats. Intravital microscopy was performed on naive WKY rats following intravenous administration of 20 mg/kg pooled anti-hMPO-positive Ig (▪) or control Ig (▵), and leukocyte responses of adhesion (A,C) and transmigration (B,D) were measured for up to 2 hours. In some rats, after 30 minutes, the Tyrode mesenteric superfusion was changed to superfusion with 3 × 10^-9 M CXCL1 (C,D), which was maintained for a further 90 minutes. The data represent the mean ± SEM, n = 5 separate rats in CXCL1 groups and n = 3 to 4 in Tyrode groups. Statistically significant differences between groups of rats are shown by asterisks, ^**P < .01, and ^***P < .001.