Chronic Smoke Exposure Burden: Impact on the Immune System of Firefighters

Firefighters are exposed to significant levels of smoke during their careers. Long-term smoke exposure has been associated with chronic diseases and cancers in firefighters. Furthermore, smoke exposure has been associated with the long-term accumulation of heavy metals (e.g., lead, arsenic), which have toxic effects. Despite these known risk factors, the impact of this pollutant burden on the immune system of firefighters remains largely unknown. The goal of this study was to characterize the immune dysfunction caused by chronic smoke exposure and identify possible associations with heavy metals in firefighters versus controls.
We profiled peripheral blood mononuclear cells (PBMCs) utilizing cytometry time of flight (CyTOF) and measured heavy metal levels in the cells during CyTOF by utilizing available heavy metal channels in a cohort of San Francisco firefighters (n=9; 21-52 years;) and healthy controls (n=9; 26-58 years) with a similar level of baseline pollution exposure. FlowJo was used to identify cell populations.
The firefighter group had a lower frequency of CD45- CCR7+CD27- NK cells in the live cell population (p<0.02) and in the NK cell population (p=0.016). Lower cell counts (p<0.05) were found in the firefighter group compared to control in B cells that were positive for Cd 106, Pb 204, and W 182 and CD4+ cells that were positive for Pb 204 and Pb 208. These results suggest chronic smoke exposure may alter the frequency of CD45- CCR7+CD27- NK cells and accumulation of certain heavy metals compared to healthy controls.
This study expands our current knowledge of potential mechanisms of immune dysfunction associated with smoke exposure and heavy metals in firefighters.