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Abstract Chronic lymphocytic leukemia (CLL) is a hematological malignancy with marked clinical heterogeneity, due in part to the genetic alterations of the leukemic cells. Its main morphological feature is the accumulation of small B lymphocytes with a mature appearance in blood, bone marrow, lymph nodes, or other lymphoid tissues (Watson et al., 2008). Approximately one-third of patients survive for 20 years or longer and not require treatment, alternatively, some patients may progress rapidly from the time of diagnosis and experience complications such as autoimmune hemolytic anemia, thrombocytopenia, and infection. CLL may also undergo transformation to prolymphocytic leukemia, with a worsening clinical outcome in most cases, which is frequently associated with abnormalities of p53 (Hercher et al., 2001) and sometimes ofc-MYC. CD62L is an adhesion molecule that, when expressed, directs the homing to, and retention of, B cells in lymph nodes and bone marrow. CD62L is over expressed on malignant B cells in lymph nodes and bone marrow of patients (Burgess et al., 2013). In this study, significantly higher levels of CD62L were demonstrated in patients with CLL compared to age matched healthy control. The study, demonstrated that relatively higher levels of CD62L expression were significantly associated with lower Hb level, platelet count and albumin. On the other hand, the demonstrated higher levels of CD62L expression were significantly associated with higher TLC, lymphocytes, Alanin Transferees (ALT), Aspartate Transferees (AST), total bilirubin and direct bilirubin. This reflects the higher tumor burden associated with higher levels of CD62L. CD62L is a surface molecule on B-cells known to play an important role in the trafficking/homing of lymphocytes to the lymph node. Increase in the expression of CD62L is accompanied by profound survival of CLL cells invitro establishing an important role of CD62L in different prosurvival stimuli provided to CLL cells by the microenvironment. The total cells in culture at day 0 was maintained at day 7, indicating persistence of the CLL population. To directly confirm that the increased levels of CD62L were expressed on CLL cells, we undertook co-expressionof CLL PBMCs with CD19 and CD62L antibodies and monitored their levels over 7 days in culture. The level of CD19+/CD62L+ cells from healthy control increased minimally over 7 days in comparison with CLL patients, which indicates increased CD62L expression is a feature of CLL cells rather than normal B cells. |