Iron in macrophages of the lungs - The world under the microscope

Purpose of the Preparation:The detection of trivalent iron in macrophages (siderophages).

Introduction[1]

In some diseases such as metabolic disorders, an accumulation of iron pigment occurs in cells. This pigment is intracellular, coarse-grained and rusty brown in color; it is "Berliner blue" positive. Increased pigment accumulation is called hemosiderosis. Usually observed in liver, spleen, lungs, kidneys, heart muscles and other organs. Causes may include malfunctions in which erythrocytes fall apart (hemosiderosis), an increased supply of blood (blood transfusions), or increased absorption of iron by the small intestine (hemochromatosis, Trousseau's disease).

The iron can be demonstrated with the 'Berliner blau' reaction. The reaction is called in German: 'Berliner blau' reaction according to Perls. In English: 'Prussian blue' reaction. Introduced by the German pathologist 'Max Perls' between 1843 and 1881.

Macrophages belong to the cleanup cells (phagocytes). They are cells of the immune system. They arise from monocytes that exit the bloodstream and transform into macrophages. Multiple macrophages can fuse to form multinucleated giant cells. According to their occurrence they are called differently such as: microglial cells in the central nervous system, kupfer cells in the liver, alveolemacrophage in the lungs (see the preparation: Rat's lungs), multinucleated osteoclasts in bone tissue, chondroclasts in cartilage tissue, histiocytes in connective tissue, hofbauer cells in the placenta.

Hemoglobin (from Greek 'Haima', blood), are iron-containing, oxygen-transporting proteins found in red blood cells (erythrocytes) of vertebrates and their variants. These take up oxygen in the lungs or gills and distribute it throughout the body. Oxygen is bound to an iron complex of protoporphyrin[2] IX (heme compound). Heme B (C34 H34 O4 N4 Fe) occurs as an iron-containing dye in red blood cells. The protein globin, which occurs together with red blood cells, forms the hemoglobin.

Degradation of hemoglobin,

If the red blood cells are at the end of their life span (about 120 days), they are broken down in the mononuclear phagocytes mainly in the spleen (and in the case of a large supply of hemoglobin to be broken down also in the liver and in the red bone marrow). Degradation begins in the spleen, and will continue in the liver. First, the globin is separated from the heme and broken down into amino acids[2]. The heme is cleaved via a cytochrome P450[2]-dependent oxygenase (heme oxygenase) to biliverdin[2], releasing divalent iron (Fe2 +) and carbon monoxide. The iron is released by the macrophage transport protein transferrin[2] present in the blood.

Hemosiderin consists of fragments of ferritin[2], the major storage protein for iron. Chemically, it is a water-insoluble complex of iron and various proteins (proteins); its iron content is about 37%. Hemosiderin, unlike ferritin, is not a physiological storage form and is therefore only found intracellularly, especially in macrophages. It has a golden yellow color that is already visible in histological sections as such but can be specifically stained with the Berliner blue reaction.

Hemosiderin (trivalent iron, Fe 3 +) arises mainly in areas of greater bleeding.

It takes some time (weeks) for the trivalent iron to form. Macrophages loaded with hemosiderin (so-called siderophages) in e.g. the sputum[2] or lungs may give indication of heart failure. Diseases with increased iron levels in the body are called hemosideroses.

Siderophages are thus macrophages that have phagocytosed hemosiderin.

- Mix 2% solution of Potassium hexacyanoferrate(II) (yellow blood leach salt) in aqua dest. in a ratio of 1:1 with a 1% HCL (hydrochloric acid) solution.

The reaction comparison is as follows:

Do not prepare the working solution until just before the reaction is to be carried out. The solution can only be used once.

All instruments such as: beakers, stirrers, spatulas etc. should be made of glass and well cleaned.

Safety: The substance is stable and the highly toxic cyanide is strongly bound under normal conditions. However, after mixing with strong acids, the highly toxic hydrocyanic acid gas is released.