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Blood Cell Count

Molecular Biology · NLM MeSH · updated 2026-10-29 · version 1

Citations verified against PubMedNot yet clinician-reviewed10 referencesApproximately 6 min read

The number of leukocytes and erythrocytes per unit volume in a sample of venous blood.

Table of Contents

1. Definition2. Research landscape3. Reading the evidence4. Open-access studies5. Key reviews6. References7. About this article

Definition and research guide

This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.

Content available: 4 complete abstracts (1,215 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.

Definition

The number of leukocytes and erythrocytes per unit volume in a sample of venous blood. A complete blood count (CBC) also includes measurement of the hemoglobin; hematocrit; and erythrocyte indices.

Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.

Also known as: Blood Cell Counts; Count, Blood Cell; Counts, Blood Cell; Blood Cell Number; Blood Cell Numbers; Number, Blood Cell; Numbers, Blood Cell; Blood Count, Complete.

Where it fits in the MeSH classification

Broader topics
Cell Count; Hematologic Tests; Blood Physiological Phenomena
Narrower topics
Erythrocyte Count; Leukocyte Count; Platelet Count

Related concepts

  • Leukocytes
  • Erythrocytes
  • Blood
  • Hemoglobin
  • Hematocrit
  • Erythrocyte Indices

Research landscape

PubMed indexes 158,725 records tagged with the MeSH heading “Blood Cell Count” (counts retrieved 2026-10-29). 16,692 of them (10.5%) were published from 2020 onward, and the busiest period so far is through 1999 with 73,212 records.

Reviews account for 6,512 records (4.1%) and meta-analyses for 1,020. Randomized controlled trials number 6,488 (4.1%) as a share of all records on the topic.

PubMed records by publication periodthrough 1999: 73,212 records; 2000-2009: 31,929 records; 2010-2019: 36,892 records; 2020 onward: 16,692 records73,212through 199931,9292000-200936,8922010-201916,6922020 onward
Records in PubMed indexed with this heading, by publication period. Real counts from NCBI E-utilities; the final period covers only part of the current year. Volume reflects how much has been published, not how strong the evidence is.
Show the data
PeriodRecords
through 199973,212
2000-200931,929
2010-201936,892
2020 onward16,692
Share of records by publication typeReviews: 4.1 percent; Meta-analyses: 0.6 percent; Randomized controlled trials: 4.1 percentReviews4.1% (6,512)Meta-analyses0.6% (1,020)Randomized controlled trials4.1% (6,488)
Share of all PubMed records on this heading that carry each publication type. Types overlap with other records, so the shares do not sum to 100%.
Publication-type chart data
Publication types among 158,725 PubMed records
TypeRecordsShare
Reviews6,5124.1%
Meta-analyses1,0200.6%
Randomized controlled trials6,4884.1%

Method: PubMed query "Blood Cell Count"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-29.

Reading the evidence in molecular biology

Molecular biology establishes mechanisms through controlled experiments, often in simplified systems such as purified proteins, cultured cells or model organisms. Such work can show what is possible in a defined system, but whether a pathway matters in a whole organism or in human disease needs further evidence. Check the experimental system, whether findings were reproduced by independent groups, and whether the authors tested the mechanism directly or inferred it from correlation.

Evidence from open-access studies

These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.

Study comparison — selected abstracts, not a systematic review
Study / authorsYearSource label / designEurope PMC citationsLicence / source
Neutrophil-to-lymphocyte ratio and mortality in the United States general population
Song M, Graubard BI, Rabkin CS, Engels EA
2021Research article
Design not recorded in structured metadata
307cc by
PMID 33431958 · DOI · PMC7801737
The Function and Role of the Th17/Treg Cell Balance in Inflammatory Bowel Disease
Yan JB, Luo MM, Chen ZY, He BH
2020Review article
Design not recorded in structured metadata
284cc by
PMID 33381606 · DOI · PMC7755495
Risk predictors of progression to severe disease during the febrile phase of dengue: a systematic review and meta-analysis
Sangkaew S, Ming D, Boonyasiri A, Honeyford K, Kalayanarooj S, Yacoub S, et al.
2021Meta-analysis
Design not recorded in structured metadata
216cc by
PMID 33640077 · DOI · PMC8240557
CD4/CD8 ratio is associated with structural reorganization of vaccine-induced immune responses in people living with HIV
Paran FJ, Saita M, Oyama R, Nomura N, Saito K, Khasawneh A, et al.
2026Research article
Design not recorded in structured metadata
0cc by
PMID 42305530 · DOI · PMC13265532

Neutrophil-to-lymphocyte ratio and mortality in the United States general population [1]

Research article Song M, Graubard BI, Rabkin CS, Engels EA · · 2021 · cited 307 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
The neutrophil-to-lymphocyte ratio (NLR) in peripheral blood reflects the balance between systemic inflammation and immunity and is emerging as a prognostic biomarker in many diseases, but its predictive role for mortality in the general population has not been investigated.
Closing excerpt
Associations over short follow-up intervals and among individuals with conditions at baseline suggest effects of disordered inflammation and immunity on progression of those conditions, while other associations may reflect contributions to disease etiology.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (250 words)

The neutrophil-to-lymphocyte ratio (NLR) in peripheral blood reflects the balance between systemic inflammation and immunity and is emerging as a prognostic biomarker in many diseases, but its predictive role for mortality in the general population has not been investigated. We analyzed 1999-2014 National Health and Nutrition Examination Survey mortality-linked data, followed up until 2015. In participants aged > 30 with measurements of differential white blood cell counts, NLR was calculated and categorized into quartiles. Associations of increased NLR with overall or cause-specific mortality were assessed with Cox proportional hazard regression models, adjusted for potential confounders. Increased NLR was associated with overall mortality (hazard ratio [HR] 1.14, 95% confidence interval [CI] 1.10-1.17, per quartile NLR) and mortality due to heart disease (1.17, 1.06-1.29), chronic lower respiratory disease (1.24, 1.04-1.47), influenza/pneumonia (1.26, 1.03-1.54) and kidney disease (1.26, 1.03-1.54). NLR was associated with cancer mortality only in the first follow-up year (HR 1.48, 95% CI 1.11-1.98). The association with chronic lower respiratory disease mortality was stronger in individuals with prevalent lung diseases (HR 1.46, 95% CI 1.14-1.88, Pinteraction = 0.01), while NLR showed positive associations with mortality from heart disease (1.21, 1.07-1.38) and cerebrovascular disease (1.30, 1.04-1.63) only among individuals without these conditions at baseline. NLR is associated with mortality overall and due to certain causes in the general population. Associations over short follow-up intervals and among individuals with conditions at baseline suggest effects of disordered inflammation and immunity on progression of those conditions, while other associations may reflect contributions to disease etiology.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 33431958 · DOI · PMC7801737

The Function and Role of the Th17/Treg Cell Balance in Inflammatory Bowel Disease [2]

Review article Yan JB, Luo MM, Chen ZY, He BH · · 2020 · cited 284 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
Inflammatory bowel disease (IBD) is a chronic, inflammatory, and autoimmune disorder.
Closing excerpt
This article focuses on our understanding of the function and role of the balance between Th17/Treg cells in IBD and these regulatory factors and their clinical significance in IBD.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (132 words)

Inflammatory bowel disease (IBD) is a chronic, inflammatory, and autoimmune disorder. The pathogenesis of IBD is not yet clear. Studies have shown that the imbalance between T helper 17 (Th17) and regulatory T (Treg) cells, which differentiate from CD4+ T cells, contributes to IBD. Th17 cells promote tissue inflammation, and Treg cells suppress autoimmunity in IBD. Therefore, Th17/Treg cell balance is crucial. Some regulatory factors affecting the production and maintenance of these cells are also important for the proper regulation of the Th17/Treg balance; these factors include T cell receptor (TCR) signaling, costimulatory signals, cytokine signaling, bile acid metabolites, and the intestinal microbiota. This article focuses on our understanding of the function and role of the balance between Th17/Treg cells in IBD and these regulatory factors and their clinical significance in IBD.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 33381606 · DOI · PMC7755495

Risk predictors of progression to severe disease during the febrile phase of dengue: a systematic review and meta-analysis [3]

Meta-analysis Sangkaew S, Ming D, Boonyasiri A, Honeyford K, Kalayanarooj S, Yacoub S, et al. · · 2021 · cited 216 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
BackgroundThe ability to accurately predict early progression of dengue to severe disease is crucial for patient triage and clinical management.
Closing excerpt
FundingWellcome Trust, National Institute for Health Research, Collaborative Project to Increase Production of Rural Doctors, and Royal Thai Government.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (603 words)

BackgroundThe ability to accurately predict early progression of dengue to severe disease is crucial for patient triage and clinical management. Previous systematic reviews and meta-analyses have found significant heterogeneity in predictors of severe disease due to large variation in these factors during the time course of the illness. We aimed to identify factors associated with progression to severe dengue disease that are detectable specifically in the febrile phase.MethodsWe did a systematic review and meta-analysis to identify predictors identifiable during the febrile phase associated with progression to severe disease defined according to WHO criteria. Eight medical databases were searched for studies published from Jan 1, 1997, to Jan 31, 2020. Original clinical studies in English assessing the association of factors detected during the febrile phase with progression to severe dengue were selected and assessed by three reviewers, with discrepancies resolved by consensus. Meta-analyses were done using random-effects models to estimate pooled effect sizes. Only predictors reported in at least four studies were included in the meta-analyses. Heterogeneity was assessed using the Cochrane Q and I2 statistics, and publication bias was assessed by Egger's test. We did subgroup analyses of studies with children and adults. The study is registered with PROSPERO, CRD42018093363.FindingsOf 6643 studies identified, 150 articles were included in the systematic review, and 122 articles comprising 25 potential predictors were included in the meta-analyses. Female patients had a higher risk of severe dengue than male patients in the main analysis (2674 [16·2%] of 16 481 vs 3052 [10·5%] of 29 142; odds ratio [OR] 1·13 [95% CI 1·01-1·26) but not in the subgroup analysis of studies with children. Pre-existing comorbidities associated with severe disease were diabetes (135 [31·3%] of 431 with vs 868 [16·0%] of 5421 without; crude OR 4·38 [2·58-7·43]), hypertension (240 [35·0%] of 685 vs 763 [20·6%] of 3695; 2·19 [1·36-3·53]), renal disease (44 [45·8%] of 96 vs 271 [16·0%] of 1690; 4·67 [2·21-9·88]), and cardiovascular disease (nine [23·1%] of 39 vs 155 [8·6%] of 1793; 2·79 [1·04-7·50]). Clinical features during the febrile phase associated with progression to severe disease were vomiting (329 [13·5%] of 2432 with vs 258 [6·8%] of 3797 without; 2·25 [1·87-2·71]), abdominal pain and tenderness (321 [17·7%] of 1814 vs 435 [8·1%] of 5357; 1·92 [1·35-2·74]), spontaneous or mucosal bleeding (147 [17·9%] of 822 vs 676 [10·8%] of 6235; 1·57 [1·13-2·19]), and the presence of clinical fluid accumulation (40 [42·1%] of 95 vs 212 [14·9%] of 1425; 4·61 [2·29-9·26]). During the first 4 days of illness, platelet count was lower (standardised mean difference -0·34 [95% CI -0·54 to -0·15]), serum albumin was lower (-0·5 [-0·86 to -0·15]), and aminotransferase concentrations were higher (aspartate aminotransferase [AST] 1·06 [0·54 to 1·57] and alanine aminotransferase [ALT] 0·73 [0·36 to 1·09]) among individuals who progressed to severe disease. Dengue virus serotype 2 was associated with severe disease in children. Secondary infections (vs primary infections) were also associated with severe disease (1682 [11·8%] of 14 252 with vs 507 [5·2%] of 9660 without; OR 2·26 [95% CI 1·65-3·09]). Although the included studies had a moderate to high risk of bias in terms of study confounding, the risk of bias was low to moderate in other domains. Heterogeneity of the pooled results varied from low to high on different factors.InterpretationThis analysis supports monitoring of the warning signs described in the 2009 WHO guidelines on dengue. In addition, testing for infecting serotype and monitoring platelet count and serum albumin, AST, and ALT concentrations during the febrile phase of illness could improve the early prediction of severe dengue.FundingWellcome Trust, National Institute for Health Research, Collaborative Project to Increase Production of Rural Doctors, and Royal Thai Government.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 33640077 · DOI · PMC8240557

CD4/CD8 ratio is associated with structural reorganization of vaccine-induced immune responses in people living with HIV [4]

Research article Paran FJ, Saita M, Oyama R, Nomura N, Saito K, Khasawneh A, et al. · · 2026

Abstract reading summary — source excerpts
Opening excerpt
BackgroundDespite effective antiretroviral therapy and sustained viral suppression, people living with HIV (PLWH) continue to exhibit persistent immune activation and low-grade inflammation.
Closing excerpt
Low CD4/CD8 ratio group showed increased monocyte-specific PPI connectivity and clonal imbalance, suggesting altered vaccine-induced response dynamics not captured by conventional clinical markers.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (230 words)

BackgroundDespite effective antiretroviral therapy and sustained viral suppression, people living with HIV (PLWH) continue to exhibit persistent immune activation and low-grade inflammation. Although the CD4/CD8 ratio is routinely monitored as a marker of immune health, the mechanisms underlying residual immune dysregulation remain incompletely understood.MethodsPeripheral blood mononuclear cells from PLWH and HC were collected before and one month after two doses of mRNA vaccination and analyzed by single-cell RNA sequencing with paired TCR profiling. Differential gene expression (DGE) and protein-protein interaction (PPI) network analyses were performed, and node degree distributions were compared among groups. TCR and bulk BCR repertoires were analyzed, and neutralizing antibody responses were assessed. PLWH were stratified by CD4/CD8 ratio.ResultsStratification by CD4/CD8 ratio revealed distinct immune states in PLWH. Differential genes from the normal CD4/CD8 ratios showed focused transcriptional activation with coordinated chemokine-associated communication, whereas those with low CD4/CD8 ratios exhibited broad transcriptional dysregulation and structural reorganization of gene-expression networks. This network signature was characterized by altered PPI topology and significantly increased monocyte-specific node degree, independent of overall transcriptional complexity. Repertoire analyses demonstrated clonal skewing and reduced clonotype diversity in the low CD4/CD8 ratio group, consistent with impaired immune coordination.ConclusionVaccine-induced immune responses in PLWH are shaped by network-level organization associated with CD4/CD8 ratio-defined immune states. Low CD4/CD8 ratio group showed increased monocyte-specific PPI connectivity and clonal imbalance, suggesting altered vaccine-induced response dynamics not captured by conventional clinical markers.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42305530 · DOI · PMC13265532

Key reviews and meta-analyses

The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.

  • Research article Association of fibrinogen, C-reactive protein, albumin, or leukocyte count with coronary heart disease: meta-analyses of prospective studies [5]
    Danesh J, Collins R, Appleby P, Peto R · JAMA · 1998 · cited 1,462 times (Europe PMC)
  • Research article Classification of platelet concentrates: from pure platelet-rich plasma (P-PRP) to leucocyte- and platelet-rich fibrin (L-PRF) [6]
    Dohan Ehrenfest DM, Rasmusson L, Albrektsson T · Trends Biotechnol · 2009 · cited 1,154 times (Europe PMC)
  • Research article Mean platelet volume: a link between thrombosis and inflammation? [7]
    Gasparyan AY, Ayvazyan L, Mikhailidis DP, Kitas GD · Curr Pharm Des · 2011 · cited 813 times (Europe PMC)
  • Research article The Relation Between Atherosclerosis and the Neutrophil-Lymphocyte Ratio [8]
    Balta S, Celik T, Mikhailidis DP, Ozturk C, Demirkol S, Aparci M, et al. · Clin Appl Thromb Hemost · 2016 · cited 259 times (Europe PMC)
  • Research article Prognostic value of PLR in various cancers: a meta-analysis [9]
    Zhou X, Du Y, Huang Z, Xu J, Qiu T, Wang J, et al. · PLoS One · 2014 · cited 252 times (Europe PMC)
  • Research article Neutrophil/lymphocyte ratio and platelet/lymphocyte ratio in mood disorders: A meta-analysis [10]
    Mazza MG, Lucchi S, Tringali AGM, Rossetti A, Botti ER, Clerici M · Prog Neuropsychopharmacol Biol Psychiatry · 2018 · cited 234 times (Europe PMC)

References

  1. Song M, Graubard BI, Rabkin CS, Engels EA. Neutrophil-to-lymphocyte ratio and mortality in the United States general population. . 2021. PMID 33431958 · DOI · PMC7801737
  2. Yan JB, Luo MM, Chen ZY, He BH. The Function and Role of the Th17/Treg Cell Balance in Inflammatory Bowel Disease. . 2020. PMID 33381606 · DOI · PMC7755495
  3. Sangkaew S, Ming D, Boonyasiri A, Honeyford K, Kalayanarooj S, Yacoub S, et al.. Risk predictors of progression to severe disease during the febrile phase of dengue: a systematic review and meta-analysis. . 2021. PMID 33640077 · DOI · PMC8240557
  4. Paran FJ, Saita M, Oyama R, Nomura N, Saito K, Khasawneh A, et al.. CD4/CD8 ratio is associated with structural reorganization of vaccine-induced immune responses in people living with HIV. . 2026. PMID 42305530 · DOI · PMC13265532
  5. Danesh J, Collins R, Appleby P, Peto R. Association of fibrinogen, C-reactive protein, albumin, or leukocyte count with coronary heart disease: meta-analyses of prospective studies. JAMA. 1998. PMID 9600484 · DOI
  6. Dohan Ehrenfest DM, Rasmusson L, Albrektsson T. Classification of platelet concentrates: from pure platelet-rich plasma (P-PRP) to leucocyte- and platelet-rich fibrin (L-PRF). Trends Biotechnol. 2009. PMID 19187989 · DOI
  7. Gasparyan AY, Ayvazyan L, Mikhailidis DP, Kitas GD. Mean platelet volume: a link between thrombosis and inflammation?. Curr Pharm Des. 2011. PMID 21247392 · DOI
  8. Balta S, Celik T, Mikhailidis DP, Ozturk C, Demirkol S, Aparci M, et al.. The Relation Between Atherosclerosis and the Neutrophil-Lymphocyte Ratio. Clin Appl Thromb Hemost. 2016. PMID 25667237 · DOI
  9. Zhou X, Du Y, Huang Z, Xu J, Qiu T, Wang J, et al.. Prognostic value of PLR in various cancers: a meta-analysis. PLoS One. 2014. PMID 24968121 · DOI · PMC4072728
  10. Mazza MG, Lucchi S, Tringali AGM, Rossetti A, Botti ER, Clerici M. Neutrophil/lymphocyte ratio and platelet/lymphocyte ratio in mood disorders: A meta-analysis. Prog Neuropsychopharmacol Biol Psychiatry. 2018. PMID 29535038 · DOI

About this article

Sources
NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
Verification
Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
Review state
automated source verified; no human expert review has been recorded yet.
Version
1, last updated 2026-10-29.

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All 100 articles in Molecular Biology →

At a glance

158,725
PubMed records on this heading
11%
published since 2020
6,512
review articles
6,488
randomized trials
10
verified references below

Counts come from PubMed on 2026-10-29; they show how much has been written, not how strong the evidence is.

Related topics See all →

  • Leukocyte CountMolecular Biology
  • CD4-CD8 RatioImmunology
  • HematocritAnatomy and Physiology
  • Partial Thromboplastin TimeAnatomy and Physiology
  • Bleeding TimeAnatomy and Physiology

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