Inflammatory macrophages in the dog contain high amounts of intravesicular ferritin and are associated with pouches of connective tissue fibers

Abstract

We have studied the subcellular distribution of ferritin in inflammatory macrophages present in regional lymph nodes from dogs subjected to a pulmonary inflammatory reaction. The inflammatory reaction was induced by intrabronchial instillation of calcium tungstate (CaWO4), a water-insoluble powder. Ferritin was identified by electron microscopy, and its electron density was enhanced by the use of a modified Perls method. From day 14 on after the CaWO4 deposition, tungsten-positive lymph node macrophages showed a massive accumulation of ferritin. Most of the ferritin was stored in membrane-bounded vesicles that showed heterogeneous concentrations of the protein. A significant complement of ferritin was also detected in the cytoplasmic ground substance of phagocytes. The cell surface of the ferritin-rich, tungsten-positive macrophages showed deep infoldings that encompassed small pockets of connective tissue fibers. These features were not observed in control samples or in lymph nodes from dogs subjected to CaWO4-induced inflammation for periods shorter than 1 week. Our data indicate that inflammatory macrophages greatly increase their content of ferritin macrophages greatly increased their content of ferritin and that ferritin is stored predominantly by a membrane-bounded vesicular compartment. This is in contrast with suggestions that the inflammation-induced increase in macrophage iron is restricted to the labile pool of iron and it does not involve the iron bound to ferritin molecules. Our observation of nodules of connective-tissue fibers in intimate topographical association with ferritin-rich macrophages may indicate that the increase in intracellular ferritin in the macrophage is in some way related to the secretion of factors by the phagocyte that will stimulate fibrillogenesis by neighboring fibroblats.

ATSDR evaluation of health effects of tungsten and relevance to public health

“…Based on relatively rapid clearance of a portion of the deposited activity from the lungs (70% was cleared with a halftime of 4 h), diffusion may account for at least a portion of the dose entering the blood. Experimental data also indicate that tungsten particles may be dissolved within alveolar macrophages (Grande et al, 1990;De Sousa Pereira et al, 1992;Peão et al, 1993) and transported to the lymphatic system (Grande et al, 1990;Águas et al, 1991). The relative solubility of a given tungsten compound also likely dictates the degree and rate of absorption.…”

Blood Vasculature of the Lymph Node in the Dog: Anatomical Evidence for Participation of Extrahilar Arterial Vessels in the Blood Supply of the Cortex

“…The lymph nodes (LN) play a central role in host defence of mammals against foreign infectious agents and particles [1][2][3][4][5]. These lymphoid organs contain all the cellu lar elements of the immune system and are capable of trig the node through the hilus and that the blood supply of the organ's parenchyma comes from branches of hilar arteries [8][9][10][11][12], According to this view, the few arterial vessels that reach the LN independently of the hilar arteries are directed to the capsule and have no or very limited partici pation in the blood supply of the lymphoid tissue.…”