Local and circulating microchimerism is associated with hypersensitivity pneumonitis

Area of Science:

• Immunology
• Pulmonary Medicine
• Genetics

Background:

• Hypersensitivity pneumonitis (HP) is an immune response to inhaled antigens, affecting only a subset of exposed individuals.
• The role of microchimerism, the presence of cells from another individual, is increasingly recognized in autoimmune and inflammatory conditions.
• Previous research suggests microchimerism may play a role in diseases with increased incidence after childbearing age.

Purpose of the Study:

• To investigate the presence and significance of microchimeric cells in female patients diagnosed with hypersensitivity pneumonitis (HP).
• To compare microchimerism frequencies between HP patients, idiopathic pulmonary fibrosis (IPF) patients, and healthy women.

Main Methods:

• Male microchimerism was assessed in 103 HP patients, 30 IPF patients, and 43 healthy women using dot blot hybridization for peripheral blood.
• Fluorescence in situ hybridization (FISH) was employed to detect microchimeric cells in bronchoalveolar lavage (BAL) fluid and lung tissue.
• Participants were women who had given birth to at least one son, excluding those with a history of transfusions or transplants.

Main Results:

• A higher frequency of blood microchimerism was observed in HP patients (33%) compared to IPF patients (10%) and healthy women (16%).
• HP patients with microchimerism exhibited significantly reduced diffusing capacity of carbon monoxide (Dl(CO)).
• Microchimeric cells, identified as macrophages or T cells (CD4+, CD8+), were detected in BAL fluid and lung tissue of HP patients.

Conclusions:

• The study demonstrates an elevated prevalence of fetal microchimerism in patients with hypersensitivity pneumonitis.
• Findings confirm that microchimeric cells can differentiate into multiple cell lineages within the host.
• The presence of microchimeric cells is suggested to potentially exacerbate disease severity in hypersensitivity pneumonitis.