Bronchus-Associated Lymphoid Tissue (BALT) Is Not Present in the Normal Adult Lung but in Different Diseases

Abstract

Bronchus-associated lymphoid tissue (BALT) was first described in the lungs of rabbits and differs greatly between species. It is part of the integrated mucosal immune system. This review clarifies its morphological definition and focuses on the situation in humans. The frequency of BALT at different ages, after chronic stimulation and in different diseases is described. In healthy humans, BALT can only be found in the lungs of children and adolescents. The role of BALT in lung transplantation and in the development of low-grade malignant lymphomas in the airways is also discussed. Furthermore, questions concerning the inducibility of BALT as an entry site for vaccines, and the regulation of its activity for future therapeutic interventions in pulmonary immune reactions are addressed.

The Role of Intrapulmonary De Novo Lymphoid Tissue in Obliterative Bronchiolitis after Lung Transplantation

“…It is possible that the presumed existence of "constitutive BALT" has made lymphoid neogenesis in the lung less obvious. However, BALT has been demonstrated not to exist in normal human lungs (29). We also observed a significantly larger number of lymphoid tissues containing HEVs in BOS lungs than in normal control lungs (Fig.…”

“…Differences among species are another important limitation of an animal experiment, particularly in the organization of intrapulmonary lymphoid tissues such as BALT (29,47). Despite these limitations, we emphasize that the animal experiments in the present study complemented the limitations in the human study in many ways and provided important insights regarding the role of intrapulmonary de novo lymphoid tissue in OB after lung transplantation.…”

Immune infiltration in human tumors: a prognostic factor that should not be ignored

“…BALT have been described in the human fetus and infant lung (Gould and Isaacson, 1993). Although they disappear in the normal adult lung (Tschernig and Pabst, 2000), they develop in lung inflammatory diseases such as fibrosis, pneumonia, hypersensitivity pneumonitis, diffuse pan-bronchiolitis and in tobacco-induced inflammation. We found that Ti-BALT are adjacent to the tumor area in NSCLC, absent in the nontumoral tissue and their number is independent of the smoking history of the patients.…”

Intraepithelial T-Cell Cytotoxicity, Induced Bronchus-Associated Lymphoid Tissue, and Proliferation of Pneumocytes in Experimental Mouse Models of Influenza

“…However, BALT is inducible in humans and mice after inflammation in the lung (40,45) (so-called iBALT). iBALT occurs in chronic lung infections in humans (53), as well as in mice with repeated virus infections of the lung (10). Mice lacking spleen, lymph nodes, and Peyer's patches develop extensive BALT in response to influenza challenge, clear influenza infection, and when BALT is present survive higher doses of the virus than do normal mice (32,47).…”