RT Journal Article SR Electronic T1 Serum paraproteins in chronic lymphocytic leukaemia. JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 463 OP 466 DO 10.1136/jcp.37.4.463 VO 37 IS 4 A1 Sinclair, D A1 Dagg, J H A1 Mowat, A M A1 Parrott, D M A1 Stott, D I YR 1984 UL http://jcp.bmj.com/content/37/4/463.abstract AB The presence of paraproteins in the sera of 10 patients with chronic lymphocytic leukaemia (CLL) was investigated using immunoisoelectric focusing. Monoclonal immunoglobulins were found in nine of these 10 sera. Five sera contained a single monoclonal IgM paraprotein, one serum contained a single monoclonal IgG paraprotein, while three sera contained more than one monoclonal paraprotein--namely, IgM + IgD, IgM + IgG, and IgM + IgD + IgG. The results indicate that the malignant B cells of CLL may be at a later stage of differentiation than previously assumed and serum monoclonal immunoglobulin could be of value as a tumour marker.