Plasma Cell Differentiation

Plasma cells are finally differentiated cells of B cell lineage. More than half amounts of serum IgG are reported to be produced by plasma cells in the BM. Thus, most plasma cells are considered to finally differentiate in the BM; microenvironments of BM support differentiation of plasma cells. Plasma cells in the BM are derived from Germinal Center(GC) B cells. GC B cells are destined to either memory B cells or plasma cells.

Early plasma cells

:CD38++VLA-5-MPC-1-

Immature plasma cells

: CD38+++VLA-5-MPC-1-

Intermediate plasma cells

:CD38+++VLA-5-MPC-1+

Mature plasma cells

:CD38+++VLA-5+MPC-1+

From GC B cells to BM plasma cells, B cell lineage differentiation is clearly identified by phenotypic analysis.

Morphologically and immunologically, these cells are distinguished.

A: morphology
B: cytoplasmic IgG staining

  • morphology(A)
  • found in the PB
  • already committed to plasma cells; SmIg-, CIgG+
  • enter apoptosis easily in vitro
  • can differentiate into mature plasma cells(B) in the presence of BM stromal cells or IL-6, anti-IL-6 antibody completely blocked this differentiation. [Blood 85:487-494, 1995]

    References

    1. Dilosa RM, et al: Germinal center B cells and antibody production in the bone marrow. J. Immunol. 146:4071-4078, 1991.
    2. Terstappen VWMM, et al: Identification and characterization of plasma cells in normal bone marrow by high-resolution flow cytometry. Blood 76:1739-1747, 1990.
    3. Liu Y, et al: Germinal centres in T-cell-dependent antibody responses. Immunol. Today 13:17-21, 1992.
    4. Harada H, et al: Phenotypic difference of normal plasma cells from mature myeloma cells. Blood 81:2658-2663, 1993.
    5. Kawano MM, et al: Identification of immature and mature myeloma cells in the bone marrow of human myeloma. Blood 82:564-570, 1993.
    6. Huang N, et al: Heterogeneous expression of a novel MPC-1 antigen on myeloma cells: Possible involvement of MPC-1 antigen in the adhesion of mature myeloma cells to bone marrow stromal cells. Blood 82:3721-3729, 1993.
    7. Kawano MM, et al: Differentiation of early plasma cells on bone marrow stromal cells requires interleukin-6 for escaping from apoptosis. Blood 85:487-494, 1995.
    8. Huang N, et al: Expression of CD21 antigen on myeloma cells and its involvement in their adhesion to bone marrow stromal cells. Blood 85:3704-3712, 1995.
    9. Harada Y, et al: Identification of early plasma cells in the peripheral blood and their clinical significance. Br.J.Haematol. (in press) 1996.
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