OBJECTIVETo investigate the incidence of serum immunoglobulin (Ig) paraprotein in chronic lymphocytic leukemia (CLL), and to explore its clinical associated laboratory features and prognostic implication.

METHODSSerum protein electrophoresis and immunofixation electrophoresis were performed by automatic electrophoresis apparatus to identify serum Ig paraprotein. Immunonephelometry was used to measure serum Ig levels.

RESULTSOut of 101 CLL patients, serum Ig paraprotein detection was found in 20 (19.8%) cases, 13 (12.9%) patients with IgG paraprotein, 7 (6.9%) patients with IgM paraprotein and 1(1.0%) patient with IgA paraprotein. Among these 20 cases, 1 patient had both IgG and IgM paraprotein, 2 patients had both κ and λ light chains. The incidence of serum IgG paraprotein was high in the group of advanced Binet stage (P = 0.032) and high level of thymidine kinase 1 (TK1) (P = 0.013). The incidence of serum IgM paraprotein was high in the group of advanced Binet stage (P = 0.037), high level of TK1 (P = 0.017) and cytogenetic abnormalities of del(11q22.3) (P = 0.006). With a median follow-up of 30 months (range 1 - 101 months), 66 patients received therapy after initial diagnosis. Survival analysis showed that the patients with serum Ig paraprotein had significantly shorter treatment-free survival (TFS) times than the patients without serum Ig paraprotein (P = 0.024). And the patients with serum IgM paraprotein had significantly shorter treatment-free survival (TFS) times than the patients without serum Ig paraprotein (P = 0.013). However, serum Ig paraprotein or IgM paraprotein was not independent prognostic factor.

CONCLUSIONSerum Ig paraprotein can be detected in a subset of patients with CLL, which could be of value as a prognostic factor in CLL.