0000000000625300
AUTHOR
Harousseau Jl
Reactive plasmacytoses are expansions of plasmablasts retaining the capacity to differentiate into plasma cells.
Abstract Circulating plasma cells in 10 cases of reactive plasmacytosis had a shared phenotype with early plasma cell (CD19+CD38+ CD138+ CD40+CD45+ CD11a+ CD49e−CD56−). In most cases, a minor subpopulation of CD28+ plasma cells was also detected. Reactive plasma cells were highly proliferative, suggesting the presence of circulating progenitors (plasmablasts). After CD138+ plasma cell removal, highly proliferative CD138− plasmablasts differentiated into CD138+ plasma cells within a few days. This differentiation, which was associated with increased CD38 and decreased HLA-DR expression, was further confirmed by a large increase in intracellular Ig content (associated with Ig secretion) and w…
CD28, a marker associated with tumoral expansion in multiple myeloma
International audience; CD28 expression was thoroughly investigated on plasma cells of monoclonal gammopathy of undetermined significance, multiple myeloma (MM), and human myeloma cell lines. CD28+ plasma cells were detected in 19% of 31 monoclonal gammopathy of undetermined significance, 41% of 116 MM, and 100% of 13 human myeloma cell lines. CD28+ myeloma cells were detected in 21 of 79 (26%) MM cases at diagnosis, 13 of 22 (59%) at medullary relapse (P < 0.009), and 14 of 15 (93%) at extramedullary relapse (P = 0.05), including 10 of 10 (100%) secondary plasma cell leukemias (P = 0.05). Serial studies in individual patients confirmed the emergence of CD28+ myeloma cells with tumoral expa…