Waldenström's macroglobulinemia is a rare disease whose pathophysiology remains at present poorly understood, although a recurrent mutation (L265P MYD88) has recently been described. Unlike other lymphoproliferative disorders, there is a defect in isotype switching, mechanism involving AID and NHEJ complex. Using a two-dimensional electrophoresis technology, our group showed that MW had a specific proteomic profile, and one of the differentially expressed proteins is Ku70 (encoded by XRCC6 belonging to NHEJ complex) .

The investigators purpose to explore the mechanisms of underexpression of Ku70/XRCC6 (genetic or epigenetic modification) in comparison with other lymphoid malignancies and normal B cells.

Inclusion Criteria:

• Patient over 18 years, affiliated to the social regimen
• Written consent collected

MW group :

• Patient with a diagnosis of MW according to WHO criteria (based on the results of serum protein electrophoresis, bone marrow analysis with immunophenotyping, cytogenetic analysis and mutation L265P MyD88)

Other SLP :

• Patient with diagnosis of Chronic Lymphocytic Leukemia, Splenic Marginal Zone Lymphoma or Multiple Myeloma

Healthy volunteers :

• volunteers without blood disorders

Exclusion Criteria:

• Women of childbearing age who do not have an effective means of contraception
• Pregnant or nursing
• Demonstration of a kappa or lambda monotype on B lymphocytes
• healthy volunteer with B-cell malignancy