Agranulocytosis:A marked decreaseinthe number ofgranulocytes. Granulocytes are a type ofwhite blood cellfilled withmicroscopicgranules that are little sacs containingenzymesthat digest microorganisms.
Granulocytes are part of the innate, somewhat non specificinfection-fightingimmune system. They do not respond exclusively to specific antigens, as do B-cells and T-cells.
Agranulocytosisresults in asyndromeof frequentchronicbacterial infectionsof theskin,lungs,throat, etc. Although "agranulocytosis" literally means no granulocytes, there may, in fact, be some granulocytes but too few of them, i.e.granulocytopenia. Agranulocytosis can begeneticand inherited or it can beacquiredas, for example, an aspect of leukemia.
Neutrophils, eosinophils and basophils are all types of granulocytes. They are named by the staining features of their granules in thelaboratory:
- Neutrophils have "neutral" subtle granules;
- Eosinophils have prominent granules that stain readily with the acid dye eosin; and
- Basophils have prominent granules that stain readily basic (non acidic) dyes.
This classification dates back to a time when certain structures could be identified in cells by histochemistry, but the functions of theseintracellularstructures were still not yet fathomed. However, the classification of granulocytes into neutrophils, eosinophils and basophils is still widely used (and quite useful).
