Adhesion of thymocytes to TEC monolayers with or without the pretreatment of the monolayers with rIL-4 (1,000 U/mL overnight). Freshly prepared thymocytes were metabolically labeled with ³⁵S and plated onto confluent TEC monolayers (untreated or rIL-4 pretreated) in serum-free culture media for 30 minutes at 37°C in the presence of either a control MoAb, an anti-α4 antibody (HP2.1), or an anti-VCAM-1 MoAb (1G11). This experiment is representative of three experiments depicted in Table 1.