To characterize and compare the CD22 promoter activity in cell culture, we analyzed the CD22 expression in two CLL cell lines (JVM-3 and MEC-1) and a non-CLL cell line (BJAB, a human Burkitt lymphoma cell line) at both the protein and mRNA levels (Fig. 2, A and B). Here, CD22 is linked to B-cell chronic lymphocytic leukemia.