The alcian blue stain is used to stain acidic mucus and acetic mucins.

Excessive amounts of non-sulfated acidic mucus are observed in mesothelioma. These phlegm are present in normal amounts in the walls of the blood vessels but increase in early lesions of atherosclerosis.

The pH of the Alcian blue staining solution is very important and has a direct effect on the category of mucins revealed by this method. The pH of the Alcian blue staining solution can be between 0.4 and 2.5.

If the pH of the solution is 1.0, the solution will stain the sulfated acid mucins. These mucins are mainly found in the cartilage, the goblet cells of the large intestine and the bronchial serous

If the Alcian blue staining solution has a pH of 2.5, it is the carboxylated mucins in the connective tissues and the cartilage that will be stained.