B cells of chronic lymphatic leukemia express V genes in unmutated form.

In order to investigate whether the leukemic B cells in B-CLL express immunoglobulin genes in mutated or unmutated form, independent cDNA clones of one patient with B-CLL expressing heavy and light chain V region genes were sequenced. The sequences of both the VH and V kappa clones were identical. The V genes could be assigned to known germline V genes. No somatic mutations were found. At the V kappa-J kappa border there is an insertion of N-sequences which are only rarely found in immunoglobulin light chain genes. Our study confirms other published data on V gene expression in B-CLL in that the surface immunoglobulins in these tumors are unmutated.