Circulating lymphocytes and the spread of myeloma. Review of the evidence.

Patients with myeloma harbour circulating lymphocytes which bear the idiotypic determinants (SIg-id+ cells) of their own myeloma protein. Circulating white cells with abnormal karyotypes have been found in other patients with this disease. SIg-id+ lymphocytes have also been identified in the peripheral blood of myeloma-tumour-bearing mice. Murine myelomas have been propagated in vivo from circulating mononuclear cells that possessed myeloma-tumour-associated antigens. This and other evidence reviewed here points strongly to the involvement of circulating lymphocyte-like stem cells in the spread of human myeloma.