The phenotype of normal, reactive and malignant plasma cells. Identification of "many and multiple myelomas" and of new targets for myeloma therapy.

The aim of this review is to integrate non-exhaustive relevant data on the phenotype of human plasma cells (PC), including normal, reactive and malignant (multiple myeloma, MM) PC. This review focuses on (i) a universal marker of both normal and malignant plasma cells, CD138; (ii) markers related to malignancy i.e., CD19, CD27, CD28, and CD56; (iii) markers associated with signaling and severity of MM (CD45, CD221). Finally, this review presents data from normal PC up to human myeloma cell lines in order to: (i) define different entities of MM based on expression of CD19, CD20, CD27 and CD117; and (ii) identify new therapeutic targets.