Oligoclonal Pattern in Serum Protein Electrophoresis
Serum protein electrophoresis (SPEP) and serum immunofixation electrophoresis (SIFE) are important diagnostic tests for multiple myeloma. In approximately 80% of myeloma cases, a single monoclonal protein is detected. Detection of biclonal and triclonal proteins occurs much less commonly.
Multiple myeloma is treatable but rarely curable. The use of new chemotherapy drugs, such as bortezomib and thalidomide congeners, and hematopoietic stem cell transplantation has significantly increased survival. The advent of these treatments has increased the incidence of oligoclonal bands being detected SPEP and SIFE. The presence of oligoclonal bands following treatment complicates the interpretation of SPEP/SIFE results. Sometimes it is difficult to determine if oligoclonal bands indicate immune reconstitution or if they include recurrent monoclonal protein.
A recent article by Dr. Gurmukh Singh increases our knowledge of oligoclonal bands. A retrospective review of the laboratory records of 227 patients with multiple myeloma was undertaken. Only patients, who had at least three SPEP/SIFE results, including at least two sets of results post transplant, were included in the study. Of the 227 total patients, 159 underwent autologous stem cell transplant (ASCT) and 68 received only chemotherapy. Almost 58% of patients who underwent stem cell transplantation exhibited oligoclonal bands, compared to only 9% of those who received only chemotherapy. More than 50% of oligoclonal bands were noted within the first year following ASCT. The earliest detectable oligoclonal band occurred at 2 months. In a few instances, oligoclonal were not detectable until 5 years after ASCT. Oligoclonal patterns were segregated by light chain. Only kappa chain was detected in 44 cases, lambda chain in 53 and both in 154 cases. In some patients, a polyclonal pattern was noted in the course of the disease either contemporaneous with the oligoclonal bands or following the disappearance of oligoclonal bands.
Oligoclonal bands are produced by clonal proliferations of B cell hematogones in bone marrow recovering from chemotherapy and are believed to indicate immune reconstitution. The clonal proliferation of transfused hematopoietic stem cells in patients treated with ASCT may also amplify the process. Oligoclonal bands may be further amplified in patients treated with allogeneic stem cell transplants due to graft versus host reaction.
The author recommends recording the position of malignant monoclonal bands to facilitate distinguishing them form oligoclonal bands following treatment. All of the oligoclonal bands were cathodic to the location of the primary malignant clone. Light chain and heavy chain types can also be used to distinguish malignant monoclonal bands and oligoclonal bands. Light chain bands of different types than those seen in the malignant clone are considered to be oligoclonal. Heavy chain bands alone or heavy chain bands with light chains in which either chain was different from that of the malignant clone are judged to be oligoclonal.
Reference
Singh G. Oligoclonal pattern/abnormal protein bands in post-treatment plasma cell myeloma patients: Implications for protein electrophoresis and serum free light chain assay results. J Clin Med Res. 2017;9(8)671-79.
