BL phenotype and TIMP-1 expression. Representative flow cytometric analysis of cell lines with differential TIMP-1 secretion as shown in Fig 1. JD38 and Daudi are negative for TIMP-1 whereas DW6, PA682, AG876, and Jijyoe express variable levels. TIMP-1–negative BL lines express high-level CD10, surface IgM, and CD77 (similar results obtained with all three TIMP-1–negative lines studied). TIMP-1⁺ BL lines show downregulation of the follicular center markers CD10, surface IgM, and CD77 along with upregulation of activation marker CD23 seen with all four TIMP-1–positive BL lines studied. The X-axis shows log fluorescence intensity. The Y-axis shows the number of cells. Horizontal bars in histograms indicate nonantibody binding as determined by irrelevant isotype control antibodies. Data are representative of five independent experiments.