Am. J. Respir. Crit. Care Med.,
Volume 161, Number 5, May 2000, 1636-1642
CD13/aminopeptidase N, a Novel Chemoattractant for
T Lymphocytes in Pulmonary Sarcoidosis
KENJI
TANI,
FUMITAKA
OGUSHI,
LUPING
HUANG,
TETSUYA
KAWANO,
HIROYA
TADA,
NORIMITSU
HARIGUCHI,
and
SABURO
SONE
Third Department of Internal Medicine, School of Medicine, Tokushima University, Tokushima, Japan
CD13/aminopeptidase N (E.C.3.4.11.2) is an ectoenzyme located
in the outer membrane of a variety of cells. Because aminopeptidase expression was shown to be upregulated by a Th1-related cytokine, IFN-
, we examined here the significance of CD13/aminopeptidase N in pulmonary sarcoidosis. The activity of aminopeptidase
in bronchoalveolar lavage fluid (BALF) was significantly higher in patients with sarcoidosis than in normal volunteers (NV) and control patients (CP). The activity significantly correlated with lymphocyte percentages and the ratio of CD4+ to CD8+ T lymphocytes
in the BALF, and was higher in patients with sarcoidosis with parenchymal involvement than in those without the involvement.
CD13/aminopeptidase N protein, which has a molecular mass of
approximately 150 kD, was detectable in alveolar macrophages
(AM) from patients with sarcoidosis at higher levels than in those
from NV. CD13/aminopeptidase N induced in vitro chemotactic
migration of human lymphocytes in a concentration range of 10
5
to 10
1 U/ml. The chemotactic activity was greater for CD4+
T lymphocytes than for CD8+ T lymphocytes. The enzymatic activity of CD13/aminopeptidase N was responsible for the chemotactic activity because bestatin, an inhibitor of CD13/aminopeptidase N,
abolished the chemotactic activity. Higher chemotactic activity for
lymphocytes was detected in the BALF from patients with sarcoidosis than in that from NV, and the activity was significantly decreased by treatment with bestatin. This study indicates that CD13/
aminopeptidase N expressed in AM may have a role in T-lymphocyte involvement in the sarcoid lung and the pathogenesis of alveolitis in this disorder.