Expression of serum monoclonal immunoglobulins in B-cell chronic lymphoproliferative disorders and their significances

Abstract

Objective To investigate the incidence of serum monoclonal immunoglobulins (McIg) in B-cell chronic lymphoproliferative disorders (B-CLPD) and the clinical significance of McIg in B-CLPD and its possible sources. Methods A total of 1 147 patients with B-CLPD treated from May 2006 to May 2015 were enrolled into this retrospective study. The incidence of McIg and the relationship between McIg and prognostic factors in patients with B-CLPD were analyzed. Results Out of 1 147 B-CLPD patients, there were 164 patients with lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia (LPL/WM), and among them, McIg was detected in 140 cases (85.4%). In the remaining 983 patients with B-CLPD, monoclonal Ig was detected in 50 (5.1%) patients. Most of McIg in 2 groups were IgM paraprotein. The levels of IgM paraprotein of the LPL/WM group, non-LPL/WM group and McIg-negative patients were (48.88 ± 33.42) g/L, (27.9 ± 15.23) g/L and (2.75±1.21) g/L, respectively, the difference was statistical significance (P=0.000); the level of IgM paraprotein in LPL/WM group was significantly higher than that in non-LPL/WM group (P=0.000). The level of paraprotein decreased significantly when the patients got complete response after therapy (P=0.001, 0.048, respectively). The incidence of serum McIg was higher in the group with complex karyotype (P=0.016) and with high level of β2-microglobulin (β2-MG) (P=0.001). In the 47 non-LPL/WM patients with positive McIg, serum McIg in 38 (80.9%) patients were expressed in a pattern consistent with the distribution of tumor cells (P<0.005). Most of the light chain subtype of the McIg were consistent with the light chain subtype of the membrane immunoglobulin on the tumor cells. Conclusions Some non-LPL/WM B-CLPD patients also have serum McIg, and it could have certain relevance with the prognosis of B-CLPD. Moreover, the McIg may be secreted by tumor cells or those derived from the same progenitor cells with tumor cells. Key words: Lymphoproliferative disorders; Immunoglobulin; Prognosis