Involvement of an IgE/Mast cell/B cell amplification loop in abdominal aortic aneurysm progression
Fig 1
IgE-producing TLOs are present in the adventitia of human AAAs.
(A) Cross-sections of AAAs were stained for CD20 (magenta) and IgE (green). Dense DAPI+ lymphoid aggregates highly enriched in CD20+ B cells correspond to TLOs. Several TLOs displayed a strong IgE staining projecting in the CD20+ B cells comprised in the DAPI “light zone” of TLOs (white arrowheads). The magnified inset shows 5 adventitial TLOs (cluster of DAPI+ CD20+ B cells), 3 of which are IgE+. adv: adventitia, m: media, thr; thrombus. Representative image of 9 different samples. Scale bar: 2.5 mm. (B) Maximum diameter size of AAAs depending on the absence (no) or the presence of TLOs. p value (Mann-Whitney test) is indicated on the plot. (C) Serial cross-sections of AAAs were coloured with Carstairs’ staining, where fibrin appears in bright pink, collagen in blue, red blood cells in yellow and nuclei in dark violet. Perl’s+DAB staining highlight redox-active iron in dark brown, nuclei have been counterstained in nuclear fast red. Orcein staining permits to detect elastin fibres in dark violet. The lumen is at the bottom of each picture and the media (m) is indicated by the blue bar on the side of the pictures. Black arrowheads point at red blood cells outside blood vessels, reminiscent of recent intramural haematomas. Scale bar: 1 mm. Right panels: magnified insets. (D) Contrast-enhanced tomography angiograms of an AAA displaying blood disruption from the aortic lumen to the aortic wall through the intraluminal thrombus (white arrow).