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 (780 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 white blood cells per unit volume in venous blood. A differential leukocyte count measures the relative numbers of the different types of white cells.
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: Count, Leukocyte; Counts, Leukocyte; Leukocyte Counts; White Blood Cell Count; Blood Cell Count, White; Leukocyte Number; Leukocyte Numbers; Number, Leukocyte.
Where it fits in the MeSH classification
- Broader topics
- Blood Cell Count
- Narrower topics
- Lymphocyte Count
- See also
- Leukocytosis
Related concepts
- White Blood Cells
- Blood
Research landscape
PubMed indexes 108,896 records tagged with the MeSH heading “Leukocyte Count” (counts retrieved 2026-10-29). 11,703 of them (10.7%) were published from 2020 onward, and the busiest period so far is through 1999 with 47,085 records.
Reviews account for 4,180 records (3.8%) and meta-analyses for 800. Randomized controlled trials number 4,854 (4.5%) as a share of all records on the topic.
Show the data
| Period | Records |
|---|---|
| through 1999 | 47,085 |
| 2000-2009 | 23,424 |
| 2010-2019 | 26,684 |
| 2020 onward | 11,703 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 4,180 | 3.8% |
| Meta-analyses | 800 | 0.7% |
| Randomized controlled trials | 4,854 | 4.5% |
Method: PubMed query "Leukocyte 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 / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Neutrophil-to-lymphocyte ratio and mortality in the United States general population | 2021 | Research article Design not recorded in structured metadata | 307 | cc by PMID 33431958 · DOI · PMC7801737 |
| The Function and Role of the Th17/Treg Cell Balance in Inflammatory Bowel Disease | 2020 | Review article Design not recorded in structured metadata | 284 | cc by PMID 33381606 · DOI · PMC7755495 |
| The Alterations in and the Role of the Th17/Treg Balance in Metabolic Diseases | 2021 | Review article Design not recorded in structured metadata | 202 | cc by PMID 34322117 · DOI · PMC8311559 |
| CD4/CD8 ratio is associated with structural reorganization of vaccine-induced immune responses in people living with HIV | 2026 | Research article Design not recorded in structured metadata | 0 | cc by PMID 42305530 · DOI · PMC13265532 |
Neutrophil-to-lymphocyte ratio and mortality in the United States general population [1]
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]
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
The Alterations in and the Role of the Th17/Treg Balance in Metabolic Diseases [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Chronic inflammation plays an important role in the development of metabolic diseases.
- Closing excerpt
- In this review, we have provided an overview of the alterations in and the functions of the Th17/Treg balance in metabolic diseases and its role in regulating immune response-related glucose and lipid metabolism.
- 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 (168 words)
Chronic inflammation plays an important role in the development of metabolic diseases. These include obesity, type 2 diabetes mellitus, and metabolic dysfunction-associated fatty liver disease. The proinflammatory environment maintained by the innate immunity, including macrophages and related cytokines, can be influenced by adaptive immunity. The function of T helper 17 (Th17) and regulatory T (Treg) cells in this process has attracted attention. The Th17/Treg balance is regulated by inflammatory cytokines and various metabolic factors, including those associated with cellular energy metabolism. The possible underlying mechanisms include metabolism-related signaling pathways and epigenetic regulation. Several studies conducted on human and animal models have shown marked differences in and the important roles of Th17/Treg in chronic inflammation associated with obesity and metabolic diseases. Moreover, Th17/Treg seems to be a bridge linking the gut microbiota to host metabolic disorders. In this review, we have provided an overview of the alterations in and the functions of the Th17/Treg balance in metabolic diseases and its role in regulating immune response-related glucose and lipid metabolism.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 34322117 · DOI · PMC8311559
CD4/CD8 ratio is associated with structural reorganization of vaccine-induced immune responses in people living with HIV [4]
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]
- Research article Timing of initiation of antiretroviral therapy in AIDS-free HIV-1-infected patients: a collaborative analysis of 18 HIV cohort studies [6]
- Research article Prognostic role of platelet to lymphocyte ratio in solid tumors: a systematic review and meta-analysis [7]
- Research article Prognostic role of neutrophil-to-lymphocyte ratio in breast cancer: a systematic review and meta-analysis [8]
- Research article Leukocyte count and coronary heart disease: implications for risk assessment [9]
- Research article Leukocytes and the risk of ischemic diseases [10]
References
- 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
- 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
- Zhang S, Gang X, Yang S, Cui M, Sun L, Li Z, et al.. The Alterations in and the Role of the Th17/Treg Balance in Metabolic Diseases. . 2021. PMID 34322117 · DOI · PMC8311559
- 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
- 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
- When To Start Consortium, Sterne JA, May M, Costagliola D, de Wolf F, Phillips AN, et al.. Timing of initiation of antiretroviral therapy in AIDS-free HIV-1-infected patients: a collaborative analysis of 18 HIV cohort studies. Lancet. 2009. PMID 19361855 · DOI · PMC2670965
- Templeton AJ, Ace O, McNamara MG, Al-Mubarak M, Vera-Badillo FE, Hermanns T, et al.. Prognostic role of platelet to lymphocyte ratio in solid tumors: a systematic review and meta-analysis. Cancer Epidemiol Biomarkers Prev. 2014. PMID 24793958 · DOI
- Ethier JL, Desautels D, Templeton A, Shah PS, Amir E. Prognostic role of neutrophil-to-lymphocyte ratio in breast cancer: a systematic review and meta-analysis. Breast Cancer Res. 2017. PMID 28057046 · DOI · PMC5217326
- Madjid M, Awan I, Willerson JT, Casscells SW. Leukocyte count and coronary heart disease: implications for risk assessment. J Am Coll Cardiol. 2004. PMID 15542275 · DOI
- Ernst E, Hammerschmidt DE, Bagge U, Matrai A, Dormandy JA. Leukocytes and the risk of ischemic diseases. JAMA. 1987. PMID 3553628 · 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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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.