[The Expression Level and Diagnostic Value of Serum Free Light Chain in B-Cell Non-Hodgkin Lymphoma].

Objective: To investigate the expression level and the diagnostic value of serum free light chain in B-cell non-Hodgkin's lymphoma (B-NHL).

Methods: We retrospectively analyzed the results of serum free light chain (sFLC) of 394 newly treated B-NHL patients in our hospital from January 2014 to December 2021 and compared the secretion levels of sFLC among different subtypes of B-NHL. The value of sFLC secretion levels in the diagnosis of WM was evaluated using ROC.

Results: Increased proportion of sFLC, abnormal ratio of sFLC (κ / λ) and the secretion levels of sFLC (κ+λ) were different in different B-NHL subtypes, Waldenstrom's macroglobulinemia (WM) had the highest proportion of elevated sFLC(82.68%) and abnormal sFLC(κ/ λ)(87.0%), the proportion of FL(18.0%) and DLBCL patients(12.8%) with elevated sFLC was lower (<0.05). The expression levels of sFLC can helpful in the diagnosis of WM (AUC=0.874，<0.001， 95% : 0.779-0.970). At the same time, higher sFLC levels and sFLC cloning patterns predicted the possibility of bone marrow infiltration of lymphoma.

Conclusion: The serum free light chains is common in patients with B-NHL. The elevated level and type of free light chain are associated with the type of lymphoma, and the patients with bone marrow infiltration have higher sFLC（κ+ λ） expression level.