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Updated: Jul 17, 2026
Quantification of Monocyte Transmigration and Foam Cell Formation from Individuals with Chronic Inflammatory Conditions
Published on: October 17, 2017
The clinical utility of elevated monocyte count in patients with fibrotic interstitial lung disease
Bohyung Min1, Daniel-Costin Marinescu2,3,4, Deborah Assayag5
1Department of Medicine, University of Calgary, Calgary, Canada.
Rationale:
Higher peripheral blood monocyte count has been associated with disease progression and mortality in patients with fibrotic interstitial lung disease (fILD), but with uncertainty regarding the strength of this association and the potential impact of confounding. This study aimed to characterise the associations of clinically ascertained peripheral blood monocyte count with survival and lung function decline in patients with fILD.
Methods:
Patients with fILD enrolled in the prospective Canadian Registry for Pulmonary Fibrosis (CARE-PF) with baseline complete blood count were included. Monocyte counts were analysed continuously and dichotomised ≥0.6 versus <0.6×109 cells·L-1 and ≥0.95 versus <0.95×109 cells·L-1. Cox proportional hazards models, unadjusted and adjusted for age, sex, lung function, smoking and treatment, evaluated associations of monocytes with transplant-free survival. Survival analysis was repeated using the prospective PROFILE cohort. Unadjusted and adjusted linear mixed models evaluated association of monocyte count with annual decline in forced vital capacity (FVC) % predicted.
Results:
In 1489 patients with fILD, higher monocyte count was associated with reduced transplant-free survival in unadjusted models, but not after adjustment for relevant confounders (continuous model, HR 0.79, 95% CI 0.54-1.17; p=0.24; dichotomised at 0.6 cells·L-1, HR 0.89, 95% CI 0.72-1.10; p=0.29; and dichotomised at 0.95 cells·L-1, HR 0.93, 95% CI 0.68-1.26; p=0.62). Findings were consistent in the PROFILE external replication cohort. Monocyte count was not associated with FVC % decline in the full cohort or within fILD subtypes.
Conclusions:
Peripheral blood monocyte count was not associated with transplant-free survival or lung function decline in this multicentre cohort study, indicating that it is not a reliable biomarker in fILD.
Insights
Peripheral blood monocyte counts do not reliably predict survival or lung function decline in fibrotic interstitial lung disease (fILD). This study found no significant association after accounting for confounding factors.
Area of Science:
- Pulmonary Medicine
- Immunology
- Biomarker Discovery
Background:
- Peripheral blood monocyte count is a potential prognostic marker in fibrotic interstitial lung disease (fILD).
- Previous studies suggest an association with disease progression and mortality, but confounding factors remain unclear.
- This uncertainty necessitates further investigation into the reliability of monocyte counts in fILD.
Purpose of the Study:
- To investigate the association between peripheral blood monocyte count and survival in patients with fILD.
- To assess the relationship between monocyte count and lung function decline (forced vital capacity - FVC).
- To determine if monocyte count is a reliable biomarker for prognosis in fILD.
Main Methods:
- Analysis of baseline complete blood counts from 1489 patients in the Canadian Registry for Pulmonary Fibrosis (CARE-PF).
- Monocyte counts were analyzed continuously and dichotomously (≥0.6 vs <0.6 and ≥0.95 vs <0.95 ×10^9 cells·L^-1).
- Cox proportional hazards models and linear mixed models were used to assess associations with survival and FVC decline, with adjustments for confounders. The study was replicated in the PROFILE cohort.
Main Results:
- Higher monocyte counts were initially associated with reduced transplant-free survival in unadjusted models.
- After adjusting for confounders (age, sex, lung function, smoking, treatment), this association was no longer significant in both the CARE-PF and PROFILE cohorts.
- Monocyte count showed no association with the annual decline in FVC % predicted in the overall cohort or fILD subtypes.
Conclusions:
- Peripheral blood monocyte count is not significantly associated with transplant-free survival in patients with fILD when adjusted for confounders.
- Monocyte count does not correlate with lung function decline in fILD.
- This study concludes that peripheral blood monocyte count is not a reliable prognostic biomarker in fibrotic interstitial lung disease.
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