Airway inflammation and upregulation of beta2 Mac-1 integrin expression on circulating leukocytes of female ragpickers in India

Abstract

Objectives: Over one million ragpickers collect and sale recyclable materials from municipal solid wastes (MSW) in India for a living. Since MSW contains a host of pathogenic microorganisms, we investigated the occurrence of airway inflammation and its underlying mechanism in 52 non-smoking female ragpickers (median age 29 yr) and 42 control women matched for age, smoking habit and socioeconomic conditions in Kolkata, eastern India.

Methods: Spontaneously expectorated sputum were stained using the Papanicolau method for cytology, and flow cytometry was used for measurements of surface expression of beta(2) Mac-1 integrin (CD11b/CD18) on leukocytes and P-selectin on platelets. The concentrations of pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) and chemokine interleukin-8 (IL-8) were measured in plasma by enzyme-linked immunosorbent assay.

Results: Compared with controls, sputum samples of ragpickers contained significantly increased numbers of alveolar macrophages, neutrophils, eosinophils and lymphocytes, suggesting airway inflammation. Circulating neutrophils and monocytes of the ragpickers overexpressed CD11b/CD18 and their platelets had upregulated surface expression of P-selectin, implying functional activation of these cells. In addition, plasma levels of IL-8 and TNF-alpha were significantly increased, indicating greater trafficking of leukocytes from circulation to the tissues. Multivariate logistic regression analysis demonstrated a positive association between the ragpicking profession and leukocyte activation after controlling for potential confounders.

Conclusions: Ragpickers experience leukocyte and platelet activation and airway inflammation that could make them more vulnerable to tissue damage and cardiovascular diseases.