Selective migration of CD18⁺ leukocytes in vivo. Analysis of CD18⁺ leukocytes in the peripheral-blood and pus collected at the same time in 2 CLAD dogs after infusion of CD18⁺ gene-corrected cells demonstrated in vivo migration of CD18⁺ leukocytes. Leukocytes were isolated from the peripheral blood and pus from infected tissue (dog A3, week 3; dog A4, week 9) and stained for CD18. Dotplots represent CD18 expression (x-axis) versus side-scatter (y-axis). Percentages of CD18⁺ leukocytes are shown at the lower right corner.