L11 blocks monocytoid cell binding to inflamed PLN HEV. Binding of WEHI78/24 cells to normal and CFA-inflamed lymph nodes was assessed in modified Stamper-Woodruff frozen section assays: WEHI78/24 cells were mixed with internal control cells (rat mesenteric lymph node lymphocytes), preincubated with isotype matched control MoAb or with L11 (0.5 μg/10⁶ cells), added to freshly cut frozen sections and incubated for 30 minutes at 5°C under constant rotation. The number of WEHI78/24 bound per rat internal standard cell in greater than 30 HEV on each of quadruplicate sections was determined by microscopy. The mean and standard error of three independent experiments are pooled and presented.