Identification and characterization of plasma cells in normal human bone marrow by high-resolution flow cytometry

Abstract

The low frequency of plasma cells and the lack of specific cell surface markers has been a major obstacle for a detailed characterization of plasma cells in normal human bone marrow. Multiparameter flow cytometry enabled the identification of plasma cells in normal bone marrow aspirates. The plasma cells were located in a unique position in the correlation of forward light scattering, orthogonal light scattering, and immunofluorescent-labeled CD38. The identity of the sorted cell populations was confirmed by microscopic examination of Wright's stained slides and slides stained for cytoplasmic immunoglobulin using polyclonal antibodies reactive with light chains; ie, anti-kappa fluorescein isothiocyanate and anti lambda phycoerythrin (PE). The purity of the sorted plasma cells was greater than 97% (n = 4). The average frequency of plasma cells in normal bone marrow aspirates was low--0.25% of the nucleated cells (n = 7)--but surprisingly consistent between individuals (SD = .05; range 0.14% to 0.30%). A detailed analysis showed two distinct populations of plasma cells: (1) A population relatively smaller by forward light scattering expressed CD22, CD35, and sigE and was identified as early plasma cells (ie, lymphoplasmacytoid), and (2) a population larger by forward light scattering lacked these markers and was identified as mature plasma cells. The antigenic profile of the normal plasma cells was determined in two-color immunofluorescence studies. The expression of cell surface immunoglobulin G (IgG), IgA, IgE, IgD, IgM, and the cell surface antigens CD10, CD11b, CD13, CD11c, CD14, CD15, CD16, CD19, CD22, CD20, CD33, CD35, CD45, and HLA-DR was determined on the plasma cells. A significant heterogeneity in cell surface antigen expression was observed within the plasma cell population. Unexpectedly, myeloid- specific cell surface antigens such as CD33 and CD13 and the early B- cell antigen identified by CD10 were expressed on a proportion of plasma cells. These observations imply that the association of myeloid and early B-cell markers described in multiple myeloma may not be associated with the neoplasia but is a normal phenomenon.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

“…Different from blood PB/PC, CD19 is clearly differentially expressed among mature BM and mucosal lamina propria, and CD19 − PC shown consistent features of PC that have reached an exceptionally mature state [ 901 , 1078 , 1116 ]. The frequency of PC in BM cell suspensions is usually greater than in the blood, amounting to 0.5-2% in mononuclear cells after density gradient enrichment, or, to <0.5% of nucleated cells in total BM aspirates [ 1117 , 1118 ]. Donor age may influence the abundance of blood PB/PC and BM PC [ 1106 , 1119 ].…”

Majority of human circulating plasmablasts stop blasting: A probable misnomer

“…With each infection or vaccination, despite the addition of 10,000-100,000 newly-minted ASC 12,16 , only a small fraction undergoes maturation into LLPC 13 . Of the total BM nucleated cells, the ASC pool represents a tiny fraction (0.1%-0.3%) over a lifetime 41 . Thus, FACS sorting rare ASC populations with total purity has rendered technical limitations for bulk proliferation studies due to contaminating B cells that may undergoing proliferation.…”

Advancing Cell Therapies: Single-Cell Profiling, Generation, Expansion, and Gene Delivery in Rhesus Macaque Plasma B Cells

“…Examining the genomic profile in NHP cell products is crucial for understanding how likely experiments using these cells are going to mimic a human cell product. Using flow cytometry, Terstappen et al showed that the canonical human PC marker, CD38 is expressed by NHP bone marrow-derived PCs 10 . Furthermore, single-cell RNA sequencing was used to demonstrate that NHP PCs from blood, bone marrow, and lymph nodes express similar factors as human primary PCs.…”