Ratio of monocytes to lymphocytes in peripheral blood in patients diagnosed with active tuberculosis.
Globally there were an estimated 8.6 million new cases of tuberculosis (TB) in 2013 and 1.3 million deaths. (1) China and India have the greatest burden of disease. India and China alone accounted for 26% and 12% of total cases, respectively. (1) In the most Western European countries and United States, the majority of cases occur in foreign-born residents and recent immigrants from countries in which TB is endemic. (2-4) TB is presenting new challenges as a global health problem, especially with new threats of HIV coinfection and drug-resistant strains of Mycobacterium tuberculosis (Mtb). (5) The knowledge about the hematological manifestations of Mtb infection is critically important to provide insight into pathogenesis. For decades, myeloid-specific cells have been known to serve as host cells for Mtb growth and lymphoid cells are thought to be the major effector cells in TB immunity. Given the central role of monocytes and lymphocytes in the induction of immune responses, their levels (hereafter termed "ML ratio") in peripheral blood might be expected to reflect the state of an individual's immunity to infection.
In a recent clinical analysis of peripheral blood mononuclear cells from a cohort of South African infants the relative ratio of monocytes to lymphocytes at the start of monitoring was shown to predict risk of developing tuberculosis disease during follow-up. (6)
Others reported that the ratio of lymphocytes to monocytes in peripheral blood correlated with the extent of tuberculosis in both rabbits (7) and humans, (8) but the numbers studied were small and the strength of the conclusions that could be reached in humans was deemed to be modest. The direct characterization of ML ratio to date has been surprisingly limited. There was no strong evidence that ML ratio was affected by Mtb infection in humans.
To start with this, using full differential blood count data from patients with active tuberculosis and healthy donors, we sought to determine whether ML ratio could be affected by tuberculosis or ongoing anti-TB treatment and provide insight into its pathogenesis.
Study population and ethics statement
Data from all subjects in the present retrospective review were collected from the clinical database of The Fifth People's Hospital of Wuxi, Affiliated to Jiangnan University, between December 2010 and June 2013. This study was approved by the Institutional Ethics Committee of The Fifth People's Hospital of Wuxi, Affiliated to Jiangnan University (QD-2013-0016), and was in compliance with the national legislation and the Declaration of Helsinki guidelines. Written patient consent was obtained according to the institutional guidelines.
Participants clinical diagnosis and treatment
Healthy donors were from the physical examination center of our hospital and met the following criteria: no history of previous active TB or TB treatment, no evidence of current active TB (absence of cough, intermittent fever, and excessive night sweating in the past two weeks and absence of unexplained weight loss in the past month). Tuberculosis was diagnosed when subjects with clinical and/or imaging features compatible with tuberculosis had at least one of the following criteria: positive sputum smear for acid-fast bacilli (AFB); positive culture for M. tuberculosis; biopsy suggestive of tuberculosis, and/or full response to anti-tuberculosis treatment. Patients with extrapulmonary TB accompanying pulmonary TB involvement were included in the category of extrapulmonary TB. Treatment of new cases, both pulmonary and extrapulmonary tuberculosis, received two months of isoniazid (H), rifampicin (R), pyrazinamide (Z) and ethambutol (E) during an intensive phase and four months of HR in the continuation phase. The duration of treatment was six months. Several kinds of extrapulmonary tuberculosis were more difficult to cure. Treatment for an extended period of time was required to ensure disease control. Such as, prolonged therapy had been adopted in TB meningitis (9-12 months) and bone and joint TB (9 months; Fig. 1). (9)
Full differential blood counts
Full blood counts (FBC) of peripheral blood collected in ethylene-diamine tetra-acetic acid containing (EDTA) tubes were performed by one of two clinical diagnostic laboratories each using a five-part differential hematology analyser (Sysmex Model XS, Hamburg, Germany). Full blood count measurement was subject to strict quality assurance procedures including twice-daily high and low internal quality control, fortnightly quality controls done by the Wuxi clinical laboratory QC scheme (Wuxi, Jiangsu, China) and annual quality assurance as part of Jiangsu clinical laboratory QC scheme. Both laboratories are accredited by the China National Accreditation System in accordance with international standards ISO 17025/2005 and ISO 15189/2007.
Statistical analysis was conducted using SPSS version 17.0. Pearson's chi-square test and Mann-Whitney U test were used to identify significant differences across patients and healthy donors, patients before treatment and after treatment. p <0.05 (two-sided) was considered as statistically significant difference. The odds ratios (OR) were estimated with 95% confidence intervals (CIs) from the univariate analysis to investigate the relationship between active tuberculosis and the different ML ratios. Adjusted odds ratios (AOR) with 95% CIs were also estimated from the multivariate analysis to determine the factors associated with the different ML ratios of patients.
Characteristics of the study population
A total of 1068 patients were diagnosed with active TB in the database of The Fifth People's Hospital of Wuxi from December 2010 to June 2013. Availability of full differential blood counts when newly diagnosed with active TB (previously untreated for TB and never received anti-TB drugs for <1 month) was required to compare with healthy donors. Patients without pre-treatment data were excluded and 965 patients remained. We further excluded return-visiting patients, who experienced treatment failure or reinfection during the course of therapy, 638 patients remained. After excluding patients with viral hepatitis (viral hepatitis type A, B and C), AIDS (acquired immune deficiency syndrome), and diabetes, 464 patients remained. Individuals who were pregnant, did not agree to participate in our study, or had other diseases, such as, lung cancer, measles, syphilis, leucopenia, systemic lupus erythematosus, or rheumatoid arthritis, which were likely to influence full blood counts, were also excluded. Finally, data of full blood counts from 419 patients were included in the analysis, with a median age of 55 years, and 71.1% were men. Furthermore, in order to assess the influence of anti-TB therapy, we excluded patients who did not receive the recommended therapy, such as irregular treatment, intermittent treatment, and undertreated patients. Finally, 108 patients who had anti-TB therapy either near completion or completed remained. A total of 327 healthy volunteers were included, 207 male and 120 female subjects.
Demographic, clinical, and laboratory characteristics of the study sample
There were 746 individuals enrolled in the study: 419 patients with newly treated active tuberculosis, and 327 healthy donors without Mtb infection. Demographic and clinical characteristics and laboratory data are summarized in Table 1. There was no difference in median age or sex between patients and healthy donors. Patients with active tuberculosis had significantly higher median absolute number of white blood cell (WBC), monocytes and neutrophils than healthy donors. The median absolute number of lymphocytes of patients was significantly lower than that of healthy donors. Patients with active tuberculosis had a significantly different ML ratio to healthy donors.
Association between ML ratio and active tuberculosis, by percentile ranking of the ratio of monocytes to lymphocytes
Participants (patients and healthy donors) were stratified into categories of ML ratio of less than the 9th percentile, between the 9th and 25th percentile, and greater than the 25th percentile (Table 2). Compared to healthy donors, patients with active tuberculosis were distributed differently in the three categories: 73.9% of patients compared to 24% of healthy donors with ML ratio >the 25th percentile, 15.8% to 1.2% with ML ratio <the 9th percentile, and 10.3% to 91.4% with ML ratio between the 9th and 25th percentile, the difference was statistically significant by multi-classification analysis of Pearson's chi-square test (p < 0.001) (Table 2). As shown in Fig. 2, ML ratio of healthy donors (blue circle) centralized mostly between the blue and green lines (91.4%); ML ratio of patients (green circle) distributed mainly out of the lines (89.7%) (Fig. 2A). ML ratio of healthy donors was the most centralized data (IQR 0.08), and gathered mainly in the area where the data from patients distributed rarely (Fig. 2B). Compared to ML ratio between the 9th and 25th percentile, participants with ML ratio <the 9th percentile or >the 25th percentile had a higher likelihood to be patients with active tuberculosis (OR = 114.73, 95% CI, 39.80-330.71; OR = 89.81, 95% CI, 53.18-151.68, respectively) (Table 2). It indicated that ML ratio less than the 9th percentile or greater than the 25th percentile were significant predictors for active tuberculosis.
Factors associated with different ML ratio distribution in 334 patients
A multivariate analysis was conducted using variables of gender, age and disease classification. As shown in Table 3, our study compared the characteristics of 334 from 419 patients who had clear information of disease classification. Male patients had a higher probability to be in the group of ML ratio <9% or ML ratio >25% than female patients, but the result had no statistical significance. Compared to patients less than 23 years of age, patients older than 60 years were over 4-fold more likely to be in the group of ML ratio <9% or ML ratio >25%. Patients with extrapulmonary tuberculosis were nearly 2.5-fold more likely to be in the extreme groups (Table 3).
ML ratio of patients recovered to be nearly normal with treatment
In order to further evaluate the impact of anti-TB therapy on the ML ratio, we excluded patients who did not receive the recommended therapy, such as irregular treatment, intermittent treatment, and undertreated therapy. A total of 108 from 419 patients who had FBC with therapy either near completion or completed were remaining and was also stratified into the same three categories with ML ratio: less than the 9th percentile, between the 9th and 25th percentile, and greater than the 25th percentile. Anti-TB therapy significantly reduced ML ratio with ML ratio greater than 25th percentile (median ML ratio, 0.472 (IQR, 0.33-0.62) before treatment us 0.2199 (IQR, 0.16-0.28) after treatment, p <0.001). ML ratio elevated significantly with ML ratio less than 9th percentile (median ML ratio, 0.026 (IQR, 0.006-0.059) before treatment us 0.197 (IQR, 0.09-0.25) after treatment, p <0.001). In patients with ML ratio between the 9th and 25th percentile, there was no difference between ML ratio before treatment (median ML ratio, 0.20 [IQR 0.15-0.23]) and after treatment (median ML ratio, 0.15 [IQR, 0.12-0.19], p = 0.166). Before anti-TB therapy, 9.3% of individuals (10/108) had ML ratio between the 9th and 25th percentile, compared with 75% (81/108) following anti-TB therapy (p<0.001). The median ML ratio of healthy donors was 0.15 (IQR, 0.12-0.19). The results indicated that higher ML ratio decreased, and lower ML ratio increased to be close to the ML ratio of healthy donors. ML ratio of patients recovered to be nearly normal with treatment.
Monocytes are an essential component of the innate immune response that acts as a link to the adaptive immune system through antigen presentation to lymphocytes. Thus any factor that perturbs the function or relative numbers of either cell type could potentially affect an individual's response to infection.
The ML ratio in peripheral circulation may reflect an individual's capacity to mount an effective immune response. ML ratio has been shown to correlate with inhibition of mycobacterial growth in uitro (10,11) and the risk is higher among individuals with either low or high ML ratio. (12) These results add to evidence supporting that extremes of immunity are associated with TB. This ratio could herald a previously unknown pathophysiologic change of TB. As demonstrated by our study, patients with active tuberculosis had a higher or lower ML ratio compared to healthy donors. We stratified participants into three categories with different ML ratios, and healthy donors were mostly in the group of ML ratio between the 9th and 25th percentile, but patients were mainly in the group of ML ratio greater than the 25th percentile and in the group of ML ratio less than the 9th percentile (Table 2). ML ratios in extreme percentiles were significant predictors for active tuberculosis.
The normal ML ratio is disrupted by Mtb infection. It has been reported recently that Mtb infection may alter subsets of hematopoietic stem cells (13) or directly infect bone marrow mesenchymal stem cells. (14) Studies in mice (15) and humans (16) have shown that subsets of hematopoietic stem cells have distinct biases in the ratio of myeloid to lymphoid cells they give rise to. (17,18) The different proportion of myeloid biased or lymphoid-biased hematopoietic stem cells may underlie the peripheral difference of ML ratio. Therefore, it is reasonable that Mtb infection may alter hematopoietic stem cells such that the ML ratio is altered. The change of monocytes and lymphocytes, reflected in their ratio, may affect patients' ability to respond to mycobacterial infection. Further work to explore the pathophysiological involvement of the ML ratio in TB may yield new pathways to modify or prevent the disease.
ML ratio of patients aged more than 60 years and extrapulmonary tuberculosis are disrupted more seriously than others. The multivariate analysis indicated that, among patients diagnosed with active tuberculosis, to be aged more than 60 years and to have extrapulmonary tuberculosis were associated with different ML ratios of patients.
In order to further evaluate whether ML ratio could be affected by anti-TB therapy, the difference between before treatment and after therapy was analyzed (Fig. 3). The results indicated that high ML ratio decreased, and low ML ratio increased to be close to the ML ratio of healthy donors. It suggested that ML ratio of patients may be changed with anti-TB therapy and the alteration of ML ratio may also reflect the effectiveness and phase of therapy.
Our study has several limitations. The eligible patients represented a fraction of the patients diagnosed with active tuberculosis during the study period, raising a concern for a selection bias. Nearly 60.8% (649/1068) of the patients were excluded. Whether the exclusion of these patients affected the outcome is unknown. As a retrospective study, collecting information from medical records filled in by other professionals is unavoidable but tends to be less accurate. Fortunately, at the time of clinical assessment, although clinicians were not blinded to the full blood count, they were not aware of this hypothesis, thus diminishing diagnostic bias.
Despite these limitations, our results support that ML ratios are disrupted with tuberculosis; ML ratios in the extreme percentiles are associated with active TB. This observation needs to be confirmed in other geographic settings.
Received 12 June 2014
Accepted 6 October 2014
Available online 18 December 2014
Conflicts of interest
The authors declare no conflicts of interest.
We thank the all patients for their support in this research and colleagues of The Fifth People's Hospital of Wuxi for their assistance in collection of research data.
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Jun Wang (a), *, , Yongmei Yin (b), , Xuedong Wang (a), , Hao Pei (a), Shougang Kuai (a), Lan Gu (b), Huiqin Xing (c), Yu Zhang (c), Qiusheng Huang (d), Bin Guan (e)
(a) Center of Clinical Laboratory, The Fifth People's Hospital of Wuxi, Affiliated to Jiangnan University, Wuxi, Jiangsu, China
(b) Radiology Department, The Fifth People's Hospital of Wuxi, Affiliated to Jiangnan University, Wuxi, Jiangsu, China
(c) Department of Basic Medical Science, Medical College, Xiamen University, Xiamen, Fujian, China
(d) Department of Respiratory Medicine, The Fifth People's Hospital of Wuxi, Affiliated to Jiangnan University, Wuxi, Jiangsu, China
(e) Department of Pharmacy, The Fifth People's Hospital of Wuxi, Affiliated to Jiangnan University, Wuxi, Jiangsu, China
* Corresponding author.
E-mail address firstname.lastname@example.org (J. Wang).
 These authors contributed equally to this article.
Table 1--Demographic, clinical, and laboratory characteristics of the study population. Characteristic Value Active Healthy donors tuberculosis (n = 327) (n = 419) Age (year) 55 (33-69) 54 (38-67) No. (%) of male subjects (b) 298 (71.1) 207 (63.3) Cell count (per [dm.sup.3]) (c) WBC 7.10 (5.51-9.20) 6.32 (5.35-7.35) Monocytes 0.50 (0.30-0.67) 0.35 (0.29-0.43) Lymphocytes 1.39 (1.02-1.80) 2.23 (1.83-2.71) ML ratio 0.36 (0.22-0.54) 0.16 (0.12-0.20) Neutrophils 4920 (3480-6990) 3510 (2780-4280) Characteristic Value p-value (a) Age (year) 0.96 No. (%) of male subjects (b) 0.02 Cell count (per [dm.sup.3]) (c) WBC <0.001 Monocytes <0.001 Lymphocytes <0.001 ML ratio <0.001 Neutrophils <0.001 (a) By Mann-Whitney or Pearson's chi-square test. (b) Data are presented as numbers (%) of individuals except indicated. (c) Data are presented as median numbers (interquartile range). Table 2--Percentile ranking of the ratio of monocytes to lymphocytes. Explanatory Value variable Active Healthy p-value (a) tuberculosis donors (n = 419) (n = 327) ML ratio between 43 (10.3) 299 (91.4) 9th and 25th percentile ML ratio <9th 66 (15.8) 4(1.2) <0.001 percentile ML ratio >25th 310 (73.9) 24 (7.4) <0.001 percentile p-value (b) <0.001 Explanatory Value variable OR (a) 95.0% CI for OR Lower Upper ML ratio between 1 9th and 25th percentile ML ratio <9th 114.733 39.803 330.716 percentile ML ratio >25th 89.816 53.181 151.687 percentile p-value (b) (a) Logistic regression analysis, abbreviations: OR, odds ratio; CI, confidence interval. (b) Pearson's chi-square test. Table 3--Factors associated with different ML ratios distribution of patients diagnosed with active tuberculosis. Active Value tuberculosis ML ratio <9th ML ratio p-value (a) percentile or between 9th and ML ratio >25th 25th percentile (304) percentile (30) Gender Male 216 (71) 24 (80) Female 88 (29) 6 (20) 0.263 Age <23 42 (13.8) 8 (26.7) 23-60 130 (42.8) 12 (40) 0.076 >60 132 (43.4) 10 (33.3) 0.01 Classification (b) Pulmonary 180 (59.2) 21 (79) tuberculosis Extrapulmonary 124 (40.8) 9 (30) 0.032 tuberculosis Active Value tuberculosis AOR (a) 95.0% CI for AOR Lower Upper Gender Male 1 Female 1.729 0.663 4.508 Age <23 1 23-60 2.537 0.907 7.097 >60 4.364 1.433 13.296 Classification (b) Pulmonary 1 tuberculosis Extrapulmonary 2.571 1.085 6.093 tuberculosis (a) Logistic regression analysis, abbreviations: AOR, adjusted odds ratio; CI, confidence interval. (b) 85 cases lack clear information of disease classification.
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|Title Annotation:||Original article|
|Author:||Wang, Jun; Yin, Yongmei; Wang, Xuedong; Pei, Hao; Kuai, Shougang; Gu, Lan; Xing, Huiqin; Zhang, Yu;|
|Publication:||The Brazilian Journal of Infectious Diseases|
|Date:||Mar 1, 2015|
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