Effector immune cells in chronic lung allograft dysfunction: A systematic review.

Area of Science:

• Immunology
• Transplantation Science
• Pulmonology

Background:

• Chronic lung allograft dysfunction (CLAD) is a primary obstacle to long-term survival following lung transplantation.
• Understanding the immunological mechanisms of CLAD is crucial for developing effective treatments.

Purpose of the Study:

• To comprehensively assess current evidence on effector immune cells in lung tissue and bronchoalveolar lavage fluid from lung transplant recipients with CLAD.
• To summarize the complex immunopathology of CLAD onset and progression over the past 20 years.

Main Methods:

• Systematic literature search of PubMed and EMBASE databases for original research publications between January 2000 and April 2021.
• Analysis of 76 selected articles focusing on effector immune cells and their products in CLAD patients.

Main Results:

• CLAD exhibits complex innate and adaptive immune cell responses, with associated cytokines, chemokines, and proteases.
• Neutrophils and eosinophils are linked to CLAD incidence, with eosinophils specifically associated with restrictive allograft syndrome.
• Restrictive allograft syndrome shows increased B cells, immunoglobulins, and complement deposition, indicating prominent humoral immune involvement.

Conclusions:

• The immunopathology of CLAD is multifactorial, involving various effector immune cells.
• Key effector immune cell phenotypes in CLAD pathogenesis are identified, but spatial resolution studies in lung tissue are limited.
• Further research, particularly single-cell resolution spatial studies, is needed to fully elucidate the role of immune cells in CLAD.