Figure 2

Lymphatic thrombosis in human emphysema. (A,B) Representative fluorescent immunohistochemical analysis of lung tissue from patients with emphysema or control smokers for the lymphatic marker PDPN (red). (C–F) Immunohistochemical staining for lymphatic thrombosis using PDPN (red) and fibrinogen (green) in lung tissue from patients with emphysema (D,F) and control smokers (C,E). Lymphatics (red) are indicated by arrowheads. (G,H) H&E staining of lung tissue revealed TLOs in emphysema (H, arrowheads) but not control lung tissue (G). (I) Quantification of PDPN⁺ lung lymphatics in tissue from control smokers and patients with moderate and very severe emphysema. (J) Quantification of PDPN⁺ lymphatic vessels with luminal fibrin. (K–N) Serial H&E and immunohistochemistry serial sections (K,L and M,N) of lung tissue from patients with very severe emphysema demonstrating thrombosed lymphatics (arrowheads) spatially associated with TLOs (asterisks). (O) Quantification of TLOs in human lung tissue. Quantification lung lymphatic vessels was performed by counting PDPN⁺ lymphatics in 10 × images of lung tissue sections. At least 3 10 × images were used for each patient tissue sample and the average lymphatic number was determined. Lymphatic thrombosis was quantified as the percentage of PDPN⁺ lung lymphatics with luminal fibrin in each 10 × image and was averaged from at least 3 10 × images. TLOs were quantified as the total number of TLOs visualized in each lung tissue sample using H&E staining. All values are means ± SEM. P value calculated by ANOVA. *P < 0.05. ns not significant. Scale bars = 25 μm.