The azurocyte: a new kind of leukocyte from wild voles (Microtus)

Abstract

We have identified a new mammalian leukocyte from voles (Cricetidae, Microtus). This "azurocyte" is a large mononuclear cell with numerous cytoplasmic inclusions that stain purple with azure dyes. The cell resembles a young lymphocyte with numerous mitochondria, a prominent Golgi complex, and modest amounts of rough endoplasmic reticulum. The inclusions are homogeneous, membrane-bound, electron-dense bodies that contain a highly acidic, sulphated glycosaminoglycan, glycoprotein, nonspecific esterase, β-glucuronidase, and an aminopeptidase. Azurocytes are common in adult voles, particularly pregnant females, and can be induced artificially with progesterone. In humans (large granular lymphocyte) and in guinea pigs (Kurloff cell), morphologically distinct cells with azurophilic inclusions have been associated with natural killer activity. The vole azurocyte may therefore be a similar leukocyte with special functions during pregnancy.