Reactive plasmacytoses are expansions of plasmablasts retaining the capacity to differentiate into plasma cells.
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 was concomitant with extensive secretion of interleukin-6 (IL-6). The addition of neutralizing anti-IL-6 and anti-CD126 (IL-6 receptor) monoclonal antibodies totally prevented Ig secretion and cell differentiation by inducing apoptosis of plasmablasts, which indicates that IL-6 is an essential survival factor for plasmablasts. This report provides the first characterization of normal plasmablasts and shows that their phenotype is not exactly that of multiple myeloma cells.
Jego
G
G
INSERM U463, Laboratoire Central d'Hématologie, Institut de Biologie, Service d'Hématologie Clinique, Hôtel-Dieu, Nantes, France.
Robillard
N
N
Puthier
D
D
Amiot
M
M
Accard
F
F
Pineau
D
D
Harousseau
J L
JL
Bataille
R
R
Pellat-Deceunynck
C
C
D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000032:analysis; D017209:Apoptosis / Q000187:drug effects; D002454:Cell Differentiation; D002478:Cells, Cultured; D002648:Child; D005260:Female; D006412:Hematopoietic Stem Cells / Q000737:chemistry / Q000473:pathology*; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000032:analysis; D007146:Immunoglobulin lambda-Chains / Q000032:analysis; D016130:Immunophenotyping; D015850:Interleukin-6 / Q000276:immunology / Q000502:physiology; D008218:Lymphocytosis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000473:pathology; D010950:Plasma Cells / Q000737:chemistry / Q000473:pathology*; D019947:Receptors, Interleukin-6 / Q000276:immunology / Q000502:physiology; D012075:Remission, Spontaneous; D012189:Retrospective Studies
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains; D015850:Interleukin-6; D019947:Receptors, Interleukin-6