To estimate the number of patients with B-cell malignancies that could be immunized with off-the-shelf cross reactive vaccines, a large database including sequences of idiotypic VH and VL genes expressed by low grade B-NHL, autoimmunity-associated lymphoproliferations (e.g. HCV-related NHL, mixed cryoglobulinemia, Sjögren’s syndrome) and CLL is currently being set up with the aim of identifying subgroups of tumors characterized by the expression of molecularly correlated Id proteins on the basis of the degree of sequence conservation among patients (R Dolcetti, unpublished results). This evidence concerns the gene ID1 and B-cell chronic lymphocytic leukemia.