Detection of VCAM-1 expression on cultured human TECs by immunoprecipitation (A) and PCR (B). (A) Immunoprecipitation of VCAM-1 from detergent lysates of biotin-labeled TECs (with or without rIL-4 pretreatment) or HUVEC (with TNF pretreatment). Immunoprecipitations with a control MoAb are shown in lanes B, D, and F. Immunoprecipitations with a combination of anti-VCAM-1 MoAbs (4B9 and 1G11) are shown in lanes A, C, and E. The constitutive expression of VCAM-1 (TEC-IL-4) is compared to the expression after overnight culture in IL-4 (TEC + IL-4). The apparent Mw of the major band (∼110 kd) in lanes A, C, and E is consistent with VCAM-1. (B) PCR analysis of VCAM-1 expression. Lanes 1 (unstimulated TEC) and 2 (IL-4 stimulated TEC) show a single major band at an apparent Mw of 650 kb consistent with the 7-domain form of VCAM-1. Lanes 4 and 5 are the actin controls for the same cells. Lanes 3 and 6 are the negative water controls.