Effects of Hematopoietic Cell Transplantation on the Pulmonary Immune Response to Infection.

Matt S Zinter,Janet R Hume

doi:10.3389/fped.2021.634566

Abstract

Pulmonary infections are common in hematopoietic cell transplant (HCT) patients of all ages and are associated with high levels of morbidity and mortality. Bacterial, viral, fungal, and parasitic pathogens are all represented as causes of infection. The lung mounts a complex immune response to infection and this response is significantly affected by the pre-HCT conditioning regimen, graft characteristics, and ongoing immunomodulatory therapy. We review the published literature, including animal models as well as human data, to describe what is known about the pulmonary immune response to infection in HCT recipients. Studies have focused on the pulmonary immune response to Aspergillus fumigatus, gram-positive and gram-negative bacteria, and viruses, and show a range of defects associated with both the innate and adaptive immune responses after HCT. There are still many open areas for research, to delineate novel therapeutic targets for pulmonary infections as well as to explore linkages to non-infectious inflammatory lung conditions.

Highlights

Hematopoietic cell transplantation (HCT) is being used for treatment of an increasing number of malignant and non-malignant disorders in all age groups, but is associated with numerous complications
Our review of the literature shows that there are a number of derangements in pulmonary immune responses associated with increased vulnerability to infection after HCT
Reconstitution of alveolar macrophages (AMs) in the lung lags behind reconstitution of peripheral leukocytes after HCT, and dendritic cells in the lung are more sensitive to radiation than AMs

Summary

INTRODUCTION

Hematopoietic cell transplantation (HCT) is being used for treatment of an increasing number of malignant and non-malignant disorders in all age groups, but is associated with numerous complications. Infections are a major complication due to immune system derangements associated with HCT. Pulmonary infections in HCT patients are caused by a range of bacteria, viruses, fungi, and protozoal agents [2, 3]. The most common pathogens change through time post-transplant as the immune function of the patient slowly recovers [2, 3]. The pulmonary immune response after HCT is not as well-documented as the systemic immune response. We examine the literature examining pulmonary immune responses to infection after HCT and find documentation in defects in both the innate and adaptive immune responses to pulmonary infection with a variety of pathogens

PULMONARY IMMUNITY AND HEMATOPOIETIC CELL TRANSPLANT

PULMONARY ASPERGILLOSIS

BACTERIAL PNEUMONIA

VIRAL INFECTIONS

Findings

DISCUSSION