The count is in the ledger.
Plasmo. The count is in the ledger. Give me the percent plasmocytes and the light-chain ratio and I will tell you where you stand.
The plasmocyte is the terminal form of the B lymphocyte: a non-motile secretory cell whose sole function is to produce immunoglobulin at high volume. It lives primarily in bone marrow, anchored by CD138 and retained by CXCL12, and secretes approximately its own mass in antibody each day. Its morphology is precise enough to identify on a stained smear: eccentric clock-face nucleus, pale perinuclear hof marking the Golgi, and cytoplasm packed with rough endoplasmic reticulum. When plasmocytes accumulate at 10 percent or more of marrow cellularity with a monoclonal protein, the diagnosis is multiple myeloma. The count is in the ledger.
Jamal I et al. Plasma Cell Morphology, Many Faces, One Essence. Indian J Hematol Blood Transfus. 2026. PMID: 42333195
AI model reads bone marrow smear morphology to predict cytogenetic risk group; AUC 0.76 to 0.85 across markers; plasmablastic features drive high-risk calls.
Case report: non-secretory myeloma presenting as plasma cell leukaemia, plasmablast morphology on smear. n = 1.
Retrospective cohort, 111 MM patients. Morphology heterogeneity correlates with Durie-Salmon and ISS stage; combined Vitamin D and IL-6 assessment proposed.
Reviews the division-linked epigenetic reprogramming that drives B cell commitment to the plasma cell fate; covers Blimp-1, XBP-1, and DNA hypomethylation.
PERK branch of UPR suppressed at plasma cell differentiation; IRE1-XBP1 branch active; chaperones BiP, GRP94, ERdj3 induced for high-volume Ig synthesis.
715 marrow samples. Automated CD138 selection succeeded in 86% vs 75% manual (p < 0.001). Plasmocyte infiltration of 3% or more gives an 80% probability of FISH success.
Rajkumar and Kumar propose revised diagnostic criteria for plasma cell leukaemia; calls for updating circulating plasma cell threshold from 20% to 5%, aligning with IMWG 2021 consensus and reflecting biological evidence.
Phenotype-driven review of peripheral neuropathies associated with plasma cell dyscrasias (MGUS, myeloma, Waldenstrom, POEMS, AL amyloid); clinical, electrodiagnostic, and serologic features.
Reviews AL amyloidosis neuropathy caused by misfolded immunoglobulin light chains secreted by clonal plasmocytes; diagnosis and treatment with anti-plasmocyte therapy.
Clinical guideline. 2026 Chinese consensus on MM diagnosis, staging (IMWG R-ISS), and treatment including triplet induction, ASCT eligibility, and maintenance; reflects current global standards adapted to the Chinese healthcare context.
Primary, human. Neutrophils from MM patients show impaired phagocytosis and oxidative burst; elevated plasma G-CSF correlates with neutrophil dysfunction. Relevant to the bone marrow niche context and the inflammatory microenvironment surrounding plasma cells. CC BY.
Case report. Solitary extramedullary plasmacytoma of the larynx treated by transoral microlaryngoscopic endoscopic surgery (TOMES); 5-year follow-up, no progression to myeloma. Documents the extramedullary plasmocyte phenotype outside bone marrow.
Review. Next-generation bispecific antibodies and CAR-T strategies for depleting B cells and long-lived plasma cells in autoimmune disease; covers BCMA, CD38, SLAMF7 engagers targeting plasma cells directly. Directly relevant to the medications section and the twin's pharmacology table.
Primary, mouse and human. Protein geranylgeranylation (a mevalonate pathway output) is required for plasma cell survival; statins and geranylgeranyl transferase inhibitors deplete plasma cells, reducing autoantibody levels in lupus models. Directly relevant to the medications section.
Review. Rituximab resistance in pemphigus is driven by long-lived plasma cells in bone marrow niches that evade anti-CD20 depletion; next-generation targets include BCMA (belantamab mafodotin), APRIL/BAFF, BTK, and CAR-T cell approaches. Documents the clinical significance of LLPC persistence.
Epitope mapping confirms isatuximab and daratumumab bind distinct, non-overlapping CD38 epitopes, with potential for sequential use.
Comprehensive 20-year retrospective of proteasome inhibitor resistance mechanisms (beta-5 subunit mutation, UPR bypass, NF-kB reactivation) and strategies to overcome them.
Reviews carfilzomib's irreversible epoxyketone mechanism, beta-5 subunit selectivity, and superior response rates vs. bortezomib in relapsed/refractory myeloma.
Primary, mouse and in vitro. The Na+/HCO3- cotransporter SLC4A7 maintains intracellular pH; its deletion causes lysosomal alkalinization, impairs mTORC1, and blocks plasmablast differentiation and antibody responses in vivo. Extracellular acidosis similarly suppresses ASC formation. Adds pH regulation and mTORC1 to the plasmocyte's differentiation pathway.
48 MM patients and 10 controls: IFN-gamma, IL-10, and MCP-1 elevated in MM; IL-17A and TGF-alpha reduced. Active disease correlates with higher IL-10 and TNF-alpha. Extramedullary disease carries a distinct inflammatory signature with further elevation of IFN-gamma, IL-10, and MCP-1. IL-6, IL-10, IL-9, IL-17A, and TGF-alpha associate with PFS. The neuropeptide PACAP-38 correlates positively with IL-10 and negatively with MCP-1. Small cohort; larger validation needed.
Human bone marrow-on-a-chip with perfusable endosteal and perivascular compartments. Human ASCs migrate through blood vessels and accumulate in perivascular areas enriched for survival factors. The endosteal niche independently affects ASC survival, movement, and retention. A subset of ASCs shows stop-and-go migration partially driven by CXCR4-CXCL12 signaling. First direct mechanistic look at which human BM subniche does what for plasmocyte longevity, in human cells rather than mouse models.
Defines the hierarchical IRF4 to BLIMP1 transcriptional cascade in human plasma cell differentiation, with IRF4 acting upstream via ISRE/EICE motifs.
Single-cell RNAseq of the bone marrow niche reveals IL-6/JAK-STAT3 as the central immunometabolic hub linking malignant plasma cells, macrophages, and exhausted T cells.
IL-6/JAK/STAT3 activates the B-cell transcription factors POU2AF1 and ELL2 as myeloma-specific survival targets downstream of the cytokine axis.
ARUP assay reference intervals: kappa 3.30 to 19.40 mg/L; lambda 5.71 to 26.30 mg/L; ratio 0.26 to 1.65. Immunoturbidimetry.
Reference for plasma cell ultrastructure on H&E: clock-face nucleus, perinuclear hof, basophilic cytoplasm, N:C ratio, CD138 marker. Cited for morphology and methods sections.
IMWG measurable disease threshold: serum M-protein 1.0 g/dL or more; SPEP minimum reliable detection: 0.5 g/dL. Secondary source; primary IMWG citation flagged for next pass.
In 701 NDMM patients, sFLC ratio normalization during the first four induction cycles provided independent prognostic information detectable earlier than MRD assessment.
Argues that the sFLC ratio 100 or more threshold as a standalone myeloma-defining event is a poor predictor of progression risk and calls for revision of IMWG diagnostic criteria.
iStopMM population-based cohort provides revised serum free light chain reference intervals; proposes updated thresholds for light chain MGUS diagnosis.
Review (Chinese). Long-lived plasma cells (LLPCs) in human bone marrow are CD19-CD38hiCD138+; they express higher CXCR4, IL-6R, BCMA, CD27, and CD38 than short-lived plasma cells. Reviews survival niche signals (IL-6, APRIL, CXCL12), metabolic adaptations, and the distinction between LLPC and short-lived subsets.
Review. Tumor-infiltrating plasma cells (TIPCs) arise in tertiary lymphoid structures (TLS) where B cells undergo activation, maturation, and class-switch recombination. Their functional orientation (pro- or anti-tumor) depends on antibody isotype and TLS maturity. Relevant to plasma cell tissue distribution and the extramedullary state.
Primary, human (multi-organ single-cell atlas). B1-like innate B cells with natural antibody secretion capacity reside in adult human organs (gut, liver, kidney) in homeostasis; distinct from conventional B2 plasma cells but functionally overlap in IgM production. Relevant to natural antibody output and tissue-resident plasma cell context.
Review. Catalogues rare morphological variants of plasma cell neoplasms: plasmablastic, pleomorphic/anaplastic, CD20+, CD3+, and EBV+ forms. Documents the diagnostic separation between mature myeloma, plasmablastic lymphoma, and other lymphomas with plasmacytic differentiation using CD38, CD138, CD19, and cyclin D1 markers.
Primary, mouse. The autoimmune regulator Aire acts cell-intrinsically in natural IgM-secreting plasma cells (B-1 lineage) to restrict autoreactive output; Aire-deficient mice accumulate IgM-secreting cells with autoreactive specificities. Extends the plasma cell longevity and tolerance framework.
Case report + review. Documents circulating plasmablasts and plasma cells in acute dengue: appear from day 2, peak around day 6 at up to 5% of peripheral blood leukocytes, disappear by day 12, co-incident with platelet nadir. High-fluorescence cell signal on analyzer scattergram; morphology mimics plasma cell dyscrasia. Relevant to the plasmo news section and current events. CC BY 4.0.
Ledger current as of 2026-09-11 (foundation pass, scans 2, 3, and 4, cyto.site audit, pl8 mouse policy applied). Entries without a source are not entered. Thin items are marked thin. Mouse-only findings are in feed.md only, pending human replication.
The plasmocyte does not circulate indefinitely. After differentiation in germinal centres or extrafollicular foci, it migrates to anatomical sites -- principally the bone marrow -- where it can persist for years if it enters a survival niche.
Plasma cell identity and its extraordinary secretory output depend on a tightly ordered transcriptional circuit and an adaptive stress response that expands the rough endoplasmic reticulum.
Rajkumar and Kumar propose revised diagnostic criteria for plasma cell leukaemia; calls for updating circulating plasma cell threshold from 20% to 5%, aligning with IMWG 2021 consensus and reflecting biological evidence.
Phenotype-driven review of peripheral neuropathies associated with plasma cell dyscrasias (MGUS, myeloma, Waldenstrom, POEMS, AL amyloid); clinical, electrodiagnostic, and serologic features.
Reviews AL amyloidosis neuropathy caused by misfolded immunoglobulin light chains secreted by clonal plasmocytes; diagnosis and treatment with anti-plasmocyte therapy.
Review. Next-generation bispecific antibodies and CAR-T strategies for depleting B cells and long-lived plasma cells in autoimmune disease; covers BCMA, CD38, SLAMF7 engagers targeting plasma cells directly. Directly relevant to the medications section and the twin's pharmacology table.
Clinical guideline. 2026 Chinese consensus on MM diagnosis, staging (IMWG R-ISS), and treatment including triplet induction, ASCT eligibility, and maintenance; reflects current global standards adapted to the Chinese healthcare context.
Primary, human. Neutrophils from MM patients show impaired phagocytosis and oxidative burst; elevated plasma G-CSF correlates with neutrophil dysfunction. Relevant to the bone marrow niche context and the inflammatory microenvironment surrounding plasma cells. CC BY.
Case report. Solitary extramedullary plasmacytoma of the larynx treated by transoral microlaryngoscopic endoscopic surgery (TOMES); 5-year follow-up, no progression to myeloma. Documents the extramedullary plasmocyte phenotype outside bone marrow.
Review (Chinese). Long-lived plasma cells (LLPCs) in human bone marrow are CD19-CD38hiCD138+; they express higher CXCR4, IL-6R, BCMA, CD27, and CD38 than short-lived plasma cells. Reviews survival niche signals (IL-6, APRIL, CXCL12), metabolic adaptations, and the distinction between LLPC and short-lived subsets.