. "\"Any process that activates or increases the frequency, rate, or extent of leukocyte migration.\" [GOC:add]" . . "positive regulation of leukocyte migration" . "positive regulation of immune cell migration" . "positive regulation of leucocyte migration" . "up regulation of leukocyte migration" . "up-regulation of leukocyte migration" . "upregulation of leukocyte migration" . . . . "activation of leukocyte migration" . "stimulation of leukocyte migration" .