Comprehensive Assessment of Flow Cytometry Light Chains: Qualitative and Quantitative Evaluation Using Serum Protein Immunofixation and Free Light Chain Analysis.

BACKGROUND

The detection of Kappa (κ) and Lambda (λ) light chains is crucial for the diagnosis and management of diseases such as multiple myeloma. Abnormal secretion of κ and λ light chains can be assessed quantitatively or qualitatively using various methods. This study aimed to compare the outcomes of κ and λ light chains and their ratio (κ/λ) in different patients with and without monoclonal gammopathies, utilizing flow cytometry, serum free light chain assays, and gel immunofixation.

METHODS

This retrospective study included data from 92 patients, both with and without monoclonal gammopathy. Patients were categorized into two groups based on serum protein electrophoresis and immunofixation: those with positive monoclonal bands (n = 77) and those without (n = 15). Simultaneous assessments of bone marrow plasma cells were conducted using flow cytometry, along with serum free κ and λ light chain assays.

RESULTS

After natural logarithm transformation, the serum κ/λ ratio was compared to the flow cytometry results for plasma cells. The κ/λ ratios showed a stronger association between serum free light chains and abnormal plasma cells (r = 0.84, p < 0.001) compared to normal plasma cells (r = 0.32, p < 0.05). Additionally, chi-squared analysis indicated a significant association for detecting free light chains for flow cytometry in comparison to serum immunofixation technique (p < 0.001) with sensitivity and specificity of 94.2% and 47.6% respectively.

CONCLUSION

Free light chain immunophenotyping using flow cytometry can serve as a complementary technique for identifying the type and quantity of positive free light chains in conjunction with immunofixation and serum free light chain assays.