D2-40 is expressed on the luminal surface of pulmonary airspaces in normal developing and adult lung but is lost in conditions associated with intra-alveolar infiltrates.

ABSTRACT The D2-40 antigen is a glycosylated sialomucin that is strongly expressed by lymphatic endothelial cells. Recently we observed the expression of D2-40 on the luminal surface of pulmonary airspaces in lung sections. The aim of the study was to assess the expression of D2-40 antigen in normal lung development and in various pathologic conditions in which abnormal alveolar infiltrates were present. Formalin-fixed lung tissue was selected from 42 fetal/neonatal autopsy cases ranging in gestational age from 12 to 41 weeks and from 10 adult lungs. In the fetal/neonatal group, 22 cases were histologically normal, whereas 20 were abnormal (including cases of pneumonia, alveolar hemorrhage, meconium aspiration, pulmonary hypoplasia, and pulmonary interstitial emphysema). In the adult group, 5 cases were histologically normal and 5 had pneumonia. Immunohistochemical staining was performed on all cases using antibody to D2-40. All cases of normal fetal/neonatal lung and normal adult lung showed diffuse stro...