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

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.