Leishman stain

Leishman stain, also known as Leishman's stain, is used in microscopy for staining blood smears. It is generally used to differentiate between and identify white blood cells, malaria parasites, and trypanosomas. It is based on a methanolic mixture of 'polychromed' methylene blue (i.e. demethylated into various azures) and eosin. The methanolic stock solution is stable and also serves the purpose of directly fixing the smear eliminating a prefixing step. If a working solution is made by dilution with an aqueous buffer, the resulting mixture is very unstable and cannot be used for long. Leishman stain is named after its inventor, the Scottish pathologist William Boog Leishman. It is a version of the Romanowsky stain, and is thus similar to and partially replaceable by Giemsa stain, Jenner's stain, and Wright's stain.There are a number of different combinations of these dyes which vary in their staining characteristics. May-Grunwald-Giemsa is a good method for routine work. Wright's stain is a simpler method, whilst Leishman's is also a simple method which is especially suitable when a stained blood film is required urgently or the routine stain is not available (e.g. at night). Field's stain is a rapid stain used primarily on thin films for malarial parasites. Whichever method is used, it is important to select dyes that are not contaminated with other dyes or metallic salts. Leishman stain, also known as Leishman's stain, is used in microscopy for staining blood smears. It is generally used to differentiate between and identify white blood cells, malaria parasites, and trypanosomas. It is based on a methanolic mixture of 'polychromed' methylene blue (i.e. demethylated into various azures) and eosin. The methanolic stock solution is stable and also serves the purpose of directly fixing the smear eliminating a prefixing step. If a working solution is made by dilution with an aqueous buffer, the resulting mixture is very unstable and cannot be used for long. Leishman stain is named after its inventor, the Scottish pathologist William Boog Leishman. It is a version of the Romanowsky stain, and is thus similar to and partially replaceable by Giemsa stain, Jenner's stain, and Wright's stain. Many companies sell Leishman Stain in the form of a dry powder, which is later reconstituted with methanol. Heat and bright light oxidize the stain, and cause the precipitation of insoluble precipitates, such as methylene violet (Bernthsen) or Azure-Eosinate salts. According to Sir John Vivian Dacie's textbook, Practical Haematology, 'Amongst the Romanowsky stains now in use, Jenner's is the simplest and Giemsa's the most complex. Leishman's stain, which occupies an intermediate position, is still widely used in the routine staining.' The WHO protocol mentions: Sir William Boog Leishman of London and Karl Reuter of Germany independently discovered in 1901 what is considered 'Perhaps the most practical modifications of Malachowski’s stain' They adopted the best aspects of the stains developed by Malachowski and Jenner, i.e., they used both polychromed methylene blue (accidentally done by Romanowsky who got the name, systematically done by Ernst Malachowski even before Romanowsky, and rediscovered by Bernhard Nocht, but unknown to Jenner, May, Grunwald and many others who used simple methylene blue) and filtering the Azure Eosinate precipitate from the aqueous mixture and redissolving in an alcoholic solvent (Jenner's wisdom). Differences between Leishman's and Reuter's methods were: Leishman used methanol (like Jenner) and substituted Eosin B for Eosin Y, whereas Reuter used ethyl alcohol and rightly stressed the importance of using an absolutely pure solvent. Both methods produced a stable stain and the desired purple color.