Expression of VCAM-1 and intracellular adhesion molecule 1 (ICAM-1) in rat skin and pleural membranes as determined by the uptake of radiolabeled anti–VCAM-1 and anti-ICAM-1 mAbs, respectively.

Skin sites (A) and pleural cavities (B) were injected with RPMI (100 μL; ■) or IL-4 (5000 units/100 μL per cavity or site; ▪). Twenty-four hours later, the animals were injected with a mixture (25 μg each) of iodine 125–labeled 5F10 (anti–VCAM-1), technetium 99m–labeled 1A29 (anti–ICAM-1), and indium 111–labeled P1.17 (control mAb) 5 minutes before they were killed. The circulation was then perfused with phosphate-buffered saline to minimize the contribution of blood-pool activity to tissue-specific isotope counts. The pleura and skin sites were removed, weighed, and counted. Expression of adhesion molecules is indicated as the percentage of injected dose per gram of tissue (ID/g), corrected for the nonspecific uptake of the control mAb. Results are expressed as the mean ± SEM value for 7 or 8 rats per group. Two asterisks indicate a significant difference (P < .001) from uptake of antibodies in RPMI-treated sites.