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Instability of Immunophenotype in Plasma Cell Myeloma

Wenqing Cao MD, Charles L. Goolsby PhD, Beverly P. Nelson MD, Seema Singhal MD, Jayesh Mehta MD, LoAnn C. Peterson MD
DOI: http://dx.doi.org/10.1309/8UVF7YQ1D4D4ETQV 926-933 First published online: 1 June 2008

Abstract

Little information has been reported describing antigen stability in plasma cell myeloma. In this study, the expression frequency and stability of 2 potential therapeutic targets, CD20 and CD52, along with the frequently aberrantly expressed CD56 antigen, were evaluated by flow cytometric analyses in 56 patients with plasma cell myeloma. Of the 56 patients, 23 (41%) showed immunophenotype change, including CD56 in 6 cases, CD20 in 7 cases, and CD52 in 17 cases. Combined CD56/CD52 change was seen in 3 cases and combined CD20/CD52 in 4 cases. No correlation was found between immunophenotype change and age, sex, stage, plasma cell morphologic features, extent of marrow involvement, time between analyses, type of therapy, or response to therapy. Immunophenotype shift was more common in patients with IgA than in patients with IgG paraprotein. Recognition of lack of stability in immunophenotype may be important, especially in antigen-directed treatment decisions and when specific phenotypes are used to detect residual disease.

Key Words:
  • Plasma cell myeloma
  • Immunophenotype
  • Flow cytometry
  • Stability