The Kurloff cell. Its differentiation in the blood and lymphatic system.

Kurloff cells belong to the group of macrophages as far as ultrastructure, adhesiveness and identification with Kupffer cells (in the case of the liver) are concerned. A characteristic group of features makes it easy to recognize them: PAS reaction, cyanol-blue staining, presence of myelin figures in electron microscopy and attachment to glass-slides. Kurloff cells are thymic and blood cells. They are observed in small numbers in the circulating blood and, in large quantities, in spleen (red pulp), liver (hepatic sinusoids) and lung (septal capillaries). They are absent from lymphatic nodules and from diffuse lymphatic tissues. Morphological and experimental studies indicate that, in spite of some equivocal similarities, Kurloff cells are distinguishable by many criteria from erythrophagocytic cells and from protein-secreting blood cells.