Differential Diagnosis and Workup of Monocytosis: A Systematic Approach to a Common Hematologic Finding

An Introduction to the Complete Blood Count for Clinical Chemists: White Blood Cells

BACKGROUND

The most frequently ordered laboratory test worldwide is the complete blood count (CBC). As clinical chemists are increasingly assigned to assist or direct laboratories outside of the traditional clinical chemistry sections, such as the automated hematology section, expertise must be established. This review article is a dedication to that ongoing effort.

CONTENT

In this primer, the white blood cell (WBC) test components of the CBC are introduced, followed by a discussion of the laboratory evaluation of leukopenia and leukocytosis.

SUMMARY

The laboratorian's approach to consult cases should be guided by the patient's clinical history and presentation while being able to provide key laboratory-based insights to assist in resolving result discrepancies that may otherwise go unnoticed.

RGS10 attenuates systemic immune dysregulation induced by chronic inflammatory stress

Regulator of G-protein signaling 10 (RGS10), a key homeostatic regulator of immune cells, has been implicated in multiple diseases associated with aging and chronic inflammation including Parkinson's Disease (PD). Interestingly, subjects with idiopathic PD display reduced levels of RGS10 in subsets of peripheral immune cells. Additionally, individuals with PD have been shown to have increased activated peripheral immune cells in cerebrospinal fluid (CSF) compared to age-matched healthy controls. However, it is unknown whether peripheral immune cells in the CSF of individuals with PD also exhibit decreased levels of RGS10. Utilizing the Michael J. Fox Foundation Parkinson's Progression Markers Initiative (PPMI) study we found that RGS10 levels are decreased in the CSF of individuals with PD compared to healthy controls and prodromal individuals. As RGS10 levels are decreased in the CSF and circulating peripheral immune cells of individuals with PD, we hypothesized that RGS10 regulates peripheral immune cell responses to chronic systemic inflammation (CSI) prior to the onset of neurodegeneration. To test this, we induced CSI for 6 weeks in C57BL6/J mice and RGS10 KO mice to assess circulating and CNS-associated immune cell responses. We found that RGS10 deficiency synergizes with CSI to induce a bias for inflammatory and cytotoxic cell populations, a reduction in antigen presentation machinery in peripheral blood immune cells, as well as in and around the brain that is most notable in males. These results highlight RGS10 as an important regulator of the systemic immune response to CSI and implicate RGS10 as a potential contributor to the development of immune dysregulation in PD.

Clonal monocytosis of renal significance

Clonal monocytosis reflects a preneoplastic or neoplastic sustained increase in the absolute monocyte count in the absence of reactive causes. Causes of clonal monocytosis include clonal cytopenias with monocytosis and acute and chronic myeloid neoplasms. Chronic myelomonocytic leukemia is a prototypical myelodysplastic/myeloproliferative overlap neoplasm in adults, characterized by sustained peripheral blood monocytosis. Kidney abnormalities, including acute kidney injury and chronic kidney disease, are frequent in patients with chronic myelomonocytic leukemia and are predictors of worse outcomes. In addition, acute kidney injury/chronic kidney disease often limits eligibility for allogeneic stem cell transplantation or enrollment in clinical trials. In this review, we highlight clonal monocytosis-related etiologies that give rise to acute kidney injury and chronic kidney disease, with special emphasis on chronic myelomonocytic leukemia and lysozyme-induced nephropathy. Monocytes produce lysozyme, which, in excess, can accumulate in and damage the proximal renal tubular epithelium. Early identification of this etiology and a timely reduction in monocyte counts can salvage kidney function. Other etiologies of kidney injury associated with clonal monocytosis include direct renal infiltration by monocytes, renal extramedullary hematopoiesis, myeloproliferative neoplasm-associated glomerulopathy, autoimmune (membranous nephropathy, minimal change disease) and paraneoplastic manifestations, thrombotic microangiopathy, obstructive nephropathy due to myeloproliferation, and urate nephropathy due to tumor lysis syndrome. We propose to group these mechanistic etiologies of kidney injury as clonal monocytosis of renal significance and provide guidance on their diagnosis and management.

RGS10 Attenuates Systemic Immune Dysregulation Induced by Chronic Inflammatory Stress

Regulator of G-protein signaling 10 (RGS10), a key homeostatic regulator of immune cells, has been implicated in multiple diseases associated with aging and chronic inflammation including Parkinson's Disease (PD). Interestingly, subjects with idiopathic PD display reduced levels of RGS10 in subsets of peripheral immune cells. Additionally, individuals with PD have been shown to have increased activated peripheral immune cells in cerebral spinal fluid (CSF) compared to age-matched healthy controls. However, it is unknown whether CSF-resident peripheral immune cells in individuals with PD also exhibit decreased levels of RGS10. Therefore, we performed an analysis of RGS10 levels in the proteomic database of the CSF from the Michael J. Fox Foundation Parkinson's Progression Markers Initiative (PPMI) study. We found that RGS10 levels are decreased in the CSF of individuals with PD compared to healthy controls and prodromal individuals. Moreover, we find that RGS10 levels decrease with age but not PD progression and that males have less RGS10 than females in PD. Importantly, studies have established an association between chronic systemic inflammation (CSI) and neurodegenerative diseases, such as PD, and known sources of CSI have been identified as risk factors for developing PD; however, the role of peripheral immune cell dysregulation in this process has been underexplored. As RGS10 levels are decreased in the CSF and circulating peripheral immune cells of individuals with PD, we hypothesized that RGS10 regulates peripheral immune cell responses to CSI prior to the onset of neurodegeneration. To test this, we induced CSI for 6 weeks in C57BL6/J mice and RGS10 KO mice to assess circulating and CNS-associated peripheral immune cell responses. We found that RGS10 deficiency synergizes with CSI to induce a bias for inflammatory and cytotoxic cell populations, a reduction in antigen presentation in peripheral blood immune cells, as well as in and around the brain that is most notable in males. These results highlight RGS10 as an important regulator of the systemic immune response to CSI and implicate RGS10 as a potential contributor to the development of immune dysregulation in PD.

Circulating monocytes decrease significantly following disease-directed therapy and may reflect disease expansion in Langerhans Cell Histiocytosis

We aimed to examine the association between relative monocytosis and the recurrence of pulmonary Langerhans Cell Histiocytosis. Clinical, laboratory, radiographic and treatment data for 86 patients with a histopathological diagnosis of Langerhans Cell Histiocytosis over a 20-year duration. Parameters such as biological sex, age at diagnosis, time to diagnosis, molecular diagnostic data and imaging were collected. Treatment responses were assessed predominantly through radiography, with RECIST 1.1 criteria applied to MRI or CT scans and PERCIST utilized for serial PET imaging. Investigators also assessed peripheral blood absolute monocyte count at various time points, including initial diagnosis and the most recently available value. While peripheral blood absolute monocyte count between the earliest assessed timepoint and latest value did not differ, the mean value on progression (0.94 K/µL), however, was significantly higher than that following re-institution of therapy (0.31, p = 0.000794. Our observation of relative monocytosis on LCH disease progression may be related to an increase in circulating LCH on disease progression or from increased monocyte production for later differentiation into mature dendritic cells that participate in MHC Class 1 upregulation. This trend is especially evident in pulmonary LCH which is incited by tissue trauma and irritation by environmental factors. The phenomena observed in our study parallel other non-LCH cohorts, specifically in published findings from our own group in patients with Rosai Dorfman and Erdheim Chester Disease. To further elucidate the molecular underpinnings of LCH and explore the etiology of this monocyte trend, expanded integrated genomic-transcriptomic sequencing analyses to evaluate the molecular character of LCH and ultimately clarify the origin of this monocyte trend are in progress. These studies are poised to offer invaluable insight to the molecular mechanisms underlying LCH, specifically as they pertain to monocyte signaling and differentiation.

Assessment of Inflammatory Hematological Ratios (NLR, PLR, MLR, LMR and Monocyte/HDL-Cholesterol Ratio) in Acute Myocardial Infarction and Particularities in Young Patients

Cardiovascular disease, particularly coronary artery disease (CAD), remains a predominant cause of mortality globally. Factors such as atherosclerosis and inflammation play significant roles in the pathogenesis of CAD. The nexus between inflammation and CAD is underscored by the role of immune cells, such as neutrophils, lymphocytes, monocytes, and macrophages. These cells orchestrate the inflammatory process, a core component in the initiation and progression of atherosclerosis. The activation of these pathways and the subsequent lipid, fibrous element, and calcification accumulation can result in vessel narrowing. Hematological parameters derived from routine blood tests offer insights into the underlying inflammatory state. Recent studies have highlighted the potential of inflammatory hematological ratios, such as the neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, monocyte/lymphocyte ratio and lymphocyte/monocyte ratio. These parameters are not only accessible and cost-effective but also mirror the degree of systemic inflammation. Several studies have indicated a correlation between these markers and the severity, prognosis, and presence of CAD. Despite the burgeoning interest in the relationship between inflammatory markers and CAD, there remains a paucity of data exploring these parameters in young patients with acute myocardial infarction. Such data could offer valuable insights into the unique pathophysiology of early-onset CAD and improve risk assessment and predictive strategies.

Therapeutic effect of intravenous acyclovir in children with infectious mononucleosis and immune function

OBJECTIVE

To explore the application value of intravenous acyclovir in children with infectious mononucleosis (IM) and its effects on immune function.

METHODS

The data of 136 children with IM treated in Anhui Provincial Children's Hospital from March 2019 to March 2022 were retrospectively analyzed. According to the inclusion and exclusion criteria, 98 children were selected. Among them, 45 children treated with routine ribavirin were assigned to the control group, and the other 53 children treated with intravenous acyclovir were enrolled into the observation group. The two groups were compared in terms of efficacy, incidence of adverse reactions, recovery time of clinical symptoms, and immune function indexes, IgG, IgA, IgM, white blood cell (WBC) count and lymphocyte proportion, before and 10 days after the treatment. Independent risk factors affecting efficacy were analyzed by multivariate logistic regression analysis.

RESULTS

The observation group showed a significantly higher overall response rate than the control group (P=0.025). The control group experienced significantly longer recovery time of body temperature returning to normal, cure time of isthmitis, time for lymph node reduction, and alleviation time of hepatomegaly than the observation group (P<0.05). Additionally, the control group presented with a significantly higher incidence of adverse reactions than the observation group (P=0.028). After treatment, the observation group showed significantly lower levels of IgG, IgA, IgM, WBC count and lymphocyte proportion than the control group (all P<0.010). Longer average course of disease (OR: 1.449, 95% CI: 1.095-1.918), higher admission temperature (OR: 6.996, 95% CI: 1.350-36.257), higher admission IgA level (OR: 4.735, 95% CI: 1.357-16.520) and higher admission IgG level (OR: 1.470, 95% CI: 1.012-2.134) were independent risk factors for ineffective efficacy, while acyclovir (OR: 0.058, 95% CI: 0.005-0.729) was an independent protective factor.

CONCLUSION

In the treatment of IM, intravenous acyclovir can substantially improve the overall clinical response rate for patients, with less adverse reactions, and can greatly alleviate various clinical symptoms and signs including fever, isthmitis, cervical lymph node enlargement, and hepatosplenomegaly, with obvious regulating effects on the immune function, so it is worth popularizing and applying in clinical practice.

Coexistence of pulmonary tuberculosis with pulmonary sarcoidosis and skin sarcoidosis: a case report

Background

Necrotising granulomatous diseases of the lungs exhibit a narrow range of differential diagnoses. Tuberculosis accounts for most of these cases, while sarcoidosis is an uncommon entity in this group but both possess similar clinical and radiological similarities. One must consider a diagnosis of sarcoidosis once the standard anti-mycobacterial medications fail to achieve a clinical improvement. The case described highlights the coexistence of tuberculosis and sarcoidosis which is a rare entity in the medical literature.

Case presentation

A 57-year-old male presented with respiratory symptoms and was diagnosed with tuberculosis (TB) demonstrating a polymerase chain reaction (PCR) test positive showing microbial DNA in bronchial washing. The patient started standard anti-TB treatment; however, he did not respond initially. Further investigations led us to diagnose pulmonary followed by skin sarcoidosis, based on histology. After confirmation of sarcoidosis, administered corticosteroids for 6 months simultaneously along with anti-TB treatment; however, anti-TB treatment was prolonged for a total of 9 months. The patient was found clinically symptomless after the completion of treatment during subsequent follow-ups.

Conclusion

The use of corticosteroids as an adjunct with standard anti-TB treatment proves beneficial effects on the recovery of patients having a coexistence of pulmonary mycobacterium tuberculosis and sarcoidosis disease conditions.

Lactococcus lactis endocarditis and liver abscess in an immunocompetent patient: a case report and review of the literature

BACKGROUND

Over the last two decades, several cases of infections caused by Lactococcus lactis have been reported. This Gram-positive coccus is considered non-pathogenic for humans. However, in some rare cases, it can cause serious infections such as endocarditis, peritonitis, and intra-abdominal infections.

CASE PRESENTATION

A 56-year-old Moroccan patient was admitted to the hospital because of diffuse abdominal pain and fever. The patient had no past medical history. Five days before his admission, he developed abdominal pain in the right lower quadrant along with chills and feverish sensations. Investigations showed a liver abscess, which was drained, and the microbiological study of the pus revealed Lactococcus lactis subsp. cremoris. Three days after admission, control computed tomography objectified splenic infarctions. Cardiac explorations were performed and showed a floating vegetation on the ventricle side of the aortic valve. We retained the diagnosis of infectious endocarditis according to the modified Duke criteria. The patient was declared afebrile on day 5 and the evolution was clinically and biologically favorable. Lactococcus lactis subsp. cremoris, formerly known as Streptococcus cremoris, is a rare cause of human infections. The first case of Lactococcus lactis cremoris endocarditis was reported in 1955. This organism includes three subspecies: lactis, cremoris, and hordniae. A MEDLINE and Scopus search showed only 13 cases of infectious endocarditis due to Lactococcus lactis, with subsp. cremoris identified in four of the cases.

CONCLUSIONS

To our knowledge, this is the first case report of the co-occurrence of Lactococcus lactis endocarditis and liver abscess. Despite its reported low virulence and good response to antibiotic treatment, Lactococcus lactis endocarditis must be considered a serious disease. It is imperative for a clinician to suspect this microorganism of causing endocarditis when they notice signs of infectious endocarditis in a patient with a history of consumption of unpasteurized dairy products or contact with farm animals. The finding of a liver abscess should lead to an investigation of endocarditis, even in previously healthy patients without obvious clinical signs of endocarditis.

Phenotypic and functional heterogeneity of monocytes in health and cancer in the era of high dimensional technologies

Monocytes have been traditionally classified in three discrete subsets, which can participate in the immune responses as effector cells or as precursors of myeloid-derived cells in circulation and tissues. However, recent advances in single-cell omics have revealed unprecedented phenotypic and functional heterogeneity that goes well beyond the three conventional monocytic subsets and propose a more fluid differentiation model. This novel concept does not only apply to the monocytes in circulation but also at the tissue site. Consequently, the binary model proposed for differentiating monocyte into M1 and M2 macrophages has been recently challenged by a spectrum model that more realistically mirrors the heterogeneous cues in inflammatory conditions. This review describes the latest results on the high dimensional characterization of monocytes and monocyte-derived myeloid cells in steady state and cancer. We discuss how environmental cues and monocyte-intrinsic properties may affect their differentiation toward specific functional and phenotypic subsets, the causes of monocyte expansion and reduction in cancer, their metabolic requirements, and the potential effect on tumor immunity.

Intravenous injection of a novel viral immunotherapy encoding human interleukin-7 in nonhuman primates is safe and increases absolute lymphocyte count

Persistence of an immunosuppression, affecting both the innate and adaptive arms of the immune system, plays a role in sepsis patients' morbidity and late mortality pointing to the need for broad and effective immune interventions. MVA-hIL-7-Fc is a non-replicative recombinant Modified Vaccinia virus Ankara encoding the human interleukin-7 fused to human IgG2 Fc fragment. We have shown in murine sepsis models the capacity of this new virotherapy to stimulate both arms of the immune system and increase survival. Herein, an exploratory study in nonhuman primates was performed following a single intravenous injection of the MVA-hIL-7-Fc used at the clinical dose to assess its safety and biological activities. Four cynomolgus macaques were followed for 3 weeks post-injection (p.i), without observed acute adverse reactions. Circulating hIL-7-Fc was detected during the first 3-5 days p.i with a detection peaking at 12 h p.i. IL-7 receptor engagement and downstream signal transduction were detected in T cells demonstrating functionality of the expressed IL-7. Expansion of blood lymphocytes, mainly CD4 and CD8 naïve and central memory T cells, was observed on day 7 p.i. together with a transient increase of Ki67 expression on T lymphocytes. In addition, we observed an increase in circulating B and NK cells as well as monocytes were albeit with different kinetics and levels. This study indicates that a vectorized IL-7-Fc, injected by intravenous route at a relevant clinical dose in a large animal model, is active without adverse reactions supporting the clinical development of this novel virotherapy for treatment of sepsis patients.

Monocyte-Lymphocyte Ratio and Dysglycemia: A Retrospective, Cross-Sectional Study of the Saudi Population

Background: Abnormalities in fasting blood glucose (FBG) resulting in hypoglycemia (OG), impaired fasting glycemia (IFG), or hyperglycemia (HG) arise from disordered metabolic regulation caused in part by inflammation. To date, there is a dearth of evidence regarding the clinical utility of the monocyte−lymphocyte ratio (MLR), an emerging inflammatory index, in the management of dysglycemia. Methods: This retrospective, cross-sectional study explored MLR fluctuations as a function of glycemic control in 14,173 Saudi subjects. Data collected from 11 August 2014 to 18 July 2020 were retrieved from Al-Borg Medical Laboratories. Medians were compared by Mann−Whitney U or Kruskal−Wallis tests and the prevalence, relative risk (RR), and odds ratio (OR) were calculated. Results: MLR was significantly elevated in IFG (p < 0.0001) and HG (p < 0.05) groups compared to the normoglycemia (NG) group, and individuals with elevated MLR (>0.191) had significantly increased FBG (p < 0.001). The risk of IFG (RR = 1.12, 95% CI: 1.06−1.19, p < 0.0002) and HG (RR = 1.10, 95% CI: 1.01−1.20, p < 0.0216) was significantly increased if MLR was elevated, and individuals with elevated MLR were 1.17 times more likely to have IFG (OR = 1.17, 95% CI: 1.08−1.26, p < 0.0002) and 1.13 times more likely to have HG (OR = 1.13, 95% CI: 1.02−1.24, p < 0.0216). Conclusion: Elevated MLR is correlated with and carries a greater risk for IFG and HG. However, large prospective cohort studies are needed to establish the temporal relationship between MLR and FBG and to examine the prognostic value of this novel marker.

Immunomagnetic leukocyte differential in whole blood on an electronic microdevice

Leukocytes are the frontline defense mechanism of the immune system. Their composition dynamically changes as a response to a foreign body, infection, inflammation, or other malignant behavior occurring within the body. Monitoring the composition of leukocytes, namely leukocyte differential, is a crucial assay periodically performed to diagnose an infection or to assess a person's vulnerability for a health anomaly. Currently, leukocyte differential analysis is performed using hematology analyzers or flow cytometers, both of which are bulky instruments that require trained and certified personnel for operation. In this work, we demonstrate a new technique to obtain leukocyte differentials in a highly portable and integrated microfluidic chip by magnetically analyzing the CD33 expression of leukocytes. When benchmarked against conventional laboratory instruments, our technology demonstrated <5% difference on average for all subtypes. Our results show that hematology testing could be performed beyond the centralized laboratories at a low cost and ultimately provide point-of-care and at-home testing opportunities.

One-step coordination of metal-phenolic networks as antibacterial coatings with sustainable and controllable copper release for urinary catheter applications

Catheter-associated urinary tract infections (CAUTIs) draw great concern due to increased demand for urinary catheters in hospitalization. Encrustation caused by urinary pathogens, especially Proteus mirabilis, results in blocking of the catheter lumen and further infections. In this study, a facile and low-cost surface modification strategy of urinary catheters was developed using one-step coordination of tannic acid (TA) and copper ions. The copper content of the coating could be manipulated by the number of TA-Cu (TC) layers, and the coating released copper in a pH-responsive manner. The coating exhibited high antibacterial efficiency (killed >99% of planktonic bacteria, and reduced biofilm coverage to <1% after 24 h) due to the synergistic antimicrobial effect of TA and copper ions. In vivo study with a rabbit model indicated that with two TC layers, the coated catheter could effectively inhibit bacterial growth in urine and colonization on the surface, and reduce encrustation formation. In addition, the TC-coated catheter exhibited better tissue compatibility compared to the unmodified catheter, probably due to the antibacterial performance of the coating. Such a straightforward coating strategy with good in vitro and in vivo antibacterial properties and biocompatibility holds great promise for combating CAUTIs in clinical practice.

The Classification of Myeloproliferative Neoplasms: Rationale, Historical Background and Future Perspectives with Focus on Unclassifiable Cases

Myeloproliferative neoplasms (MPNs) are a heterogeneous group of clonal hematopoietic stem cell disorders, characterized by increased proliferation of one or more myeloid lineages in the bone marrow. The classification and diagnostic criteria of MPNs have undergone relevant changes over the years, reflecting the increased awareness on these conditions and a better understanding of their biological and clinical-pathological features. The current World Health Organization (WHO) Classification acknowledges four main sub-groups of MPNs: (i) Chronic Myeloid Leukemia; (ii) classical Philadelphia-negative MPNs (Polycythemia Vera; Essential Thrombocythemia; Primary Myelofibrosis); (iii) non-classical Philadelphia-negative MPNs (Chronic Neutrophilic Leukemia; Chronic Eosinophilic Leukemia); and (iv) MPNs, unclassifiable (MPN-U). The latter are currently defined as MPNs with clinical-pathological findings not fulfilling the diagnostic criteria for any other entity. The MPN-U spectrum traditionally encompasses early phase MPNs, terminal (i.e., advanced fibrotic) MPNs, and cases associated with inflammatory or neoplastic disorders that obscure the clinical-histological picture. Several lines of evidence and clinical practice suggest the existence of additional myeloid neoplasms that may expand the spectrum of MPN-U. To gain insight into such disorders, this review addresses the history of MPN classification, the evolution of their diagnostic criteria and the complex clinical-pathological and biological features of MPN-U.