Recruitment factors (R-factors) for the various leukocytes found on VCAM-1–coated cover slips after perfusion of whole blood. The R-factor was defined as percentage of leukocytes present on the cover slip over the percentage found in the whole blood. An R-factor of 1 means that the percentage of a particular leukocyte found on the cover slip was equal to that found in the whole blood. *P < .05 relative to an R-factor value of 1.