B-356 A Large Reference Laboratory’s Experience Transitioning from Immunofixation to Immunotyping for Monoclonal Protein Detection

Background Multiple myeloma is a hematological malignancy most prevalent in individuals aged 65 years and older and is characterized by the presence of clonal plasma cells in the bone marrow. Diagnostic testing for multiple myeloma includes serum protein electrophoresis and serum immunofixation/immunotyping to quantify the monoclonal protein and identify the immunoglobulin isotype, respectively. Electrophoresis and immunofixation/immunotyping are performed using either a gel or a capillary separation technique. Gel electrophoresis and immunofixation are the methods used by most clinical laboratories; however, capillary electrophoresis and immunotyping usage have been increasing in recent years due to advances in technology and automation. “Though Quest Diagnostics – Chantilly has many years of experience in performing capillary electrophoresis, serum immunofixation by gel electrophoresis has remained the methodology employed for multiple myeloma diagnostic testing. To streamline processes and improve service, the laboratory transitioned to immunotyping by capillary electrophoresis. Methods To determine the impact of the switch from gel electrophoresis immunofixation (Helena SPIFE TOUCH) to immunotyping by capillary electrophoresis (Capillarys III Tetra), the change in turnaround time (collection to result), percentage of monoclonals identified, and rates of monoclonal identification by both immunofixation/immunotyping and serum protein electrophoresis monoclonal quantification were evaluated for the same 3-month period prior to the change in methodology and after the change. Results After implementation of immunotyping, turnaround time was reduced by 33%, from six days to four days. One or more monoclonal proteins were identified in 57% of samples for immunofixation and in 63% of samples for immunotyping. Two or more clones were identified in 18% of immunofixation samples and 8% of immunotyping samples. IgG kappa (42%-45%) was the predominant clone detected by both methods, followed by IgG lambda (20%-22%), IgM kappa (6%-8%), IgA kappa (6%-8%), IgA lambda (3.5%-5%), IgM lambda (2.2%-3.5%), free light chains only (∼1%) and IgD kappa and lambda (<0.25%). There was no significant difference in the percentages of the immunoglobulin heavy and light chains reported by the 2 methods. Immunofixation confirmed the presence of monoclonal proteins in 99.0% of samples resulting in abnormal protein electrophoresis, while immunotyping confirmed 98.2% of such samples Conclusion Overall, results reported for transition from immunofixation to immunotyping showed concordance in the percentage of monoclonals identified as well as the isotype Additionally, the transition from immunofixation to immunotyping resulted in several improvements for clients and patients, including a reduction in the turnaround time and decrease in multiple clones being reported. Considering, True multiple myeloma cases with 2 or more clones are thought to be rare, making up only 1%-5% of cases, this suggests that immunotyping may yield more accurate results when compared to immunofixation methods.