Significance of abnormal protein bands in patients with multiple myeloma following autologous stem cell transplantation.
OBJECTIVE
We studied the characteristics of small abnormal protein bands (APB) (including oligoclonal bands and new apparent monoclonal bands) that are frequently detected by serum protein electrophoresis (SPEP) and isoelectric focusing (IEF) in the post-autologous stem cell transplant setting.


METHODS
In a retrospective analysis of patients with multiple myeloma undergoing transplantation, paraprotein identity and quantification were performed using standard immunofixation electrophoresis. The nature of any new bands was determined by IEF which distinguished between oligoclonal bands and apparent monoclonal bands.


RESULTS
Of 49 myeloma cases, the median follow-up was 33.7 months (range, 5.6-97.5 months) and 24 patients had relapsed. Thirty six (73%) developed APB. 22 patients had more than one episode of APB and 6 patients had more than 2 episodes resulting in a total of 69 episodes of APB observed post-transplant. IEF demonstrated 54 of these APB were oligoclonal bands and 15 appeared to be monoclonal. Of the 15 episodes of apparent monoclonal bands, 10 had differing heavy or light chain restriction compared to the original myeloma paraprotein and 5 had the same heavy and light chain restriction but different band location in the SPEP lane. Ten of these apparent monoclonal bands resolved, 5 persisted, and only one represented true disease progression. The presence of APB impacted favourably on event-free survival (p=0.05).


CONCLUSIONS
Small APB are very frequent post-transplant for myeloma, and IEF can identify these APB as oligoclonal or monoclonal. Apparent monoclonal bands may represent relapsed disease, but in the vast majority of cases it does not, and most likely represents a transient phenomenon representing regeneration of a limited immune response.
Haematology Department, Pathology Queensland, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
Sara L
SL
Hall
Jill
J
Tate
Devinder
D
Gill
Peter
P
Mollee