Identification of two types of mononuclear phagocytes in the peripheral blood of rabbits

Abstract

Mallory 1 in 1898 named the mononuclear phagocyte of typhoid fever lesions endothelial leukocytes. Since that time cumulative evidence has given much support to the view that the mononuclear tissue and blood phagocytes arise from endothelium. Aschoff and Kiyono 2 by means of vital dyes traced these free cells to the reticulo-endothelium. Sabin 3 in the chick embryo saw endothelial cells detach themselves from the walls of veins and become free in the lumen of the vessel; and this author, 4 after marking the vascular endothelium by the intravenous injection of carbon in suspension, observed the carbon-laden endothelial cells to undergo mitosis and to separate and assume the same morphology as the free cells.

Recently Sabin, Doan and Cunningham 5 gave the first noteworthy evidence that these phagocytes are not of a single type, by demonstrating in peritoneal exudates with supravital stains a cell with the neutral red granules grouped in the hof of the nucleus in “rosette” form, in distinction to a second type with scattered neutral red granules. The author 6 repeated their experiments and found, in addition to the two types described by them, a third or hyaline type with little affinity for neutral red. Examination by the author of the lymph nodes, spleen and liver, fresh and in paraffin sections with the neutral red mordanted insitu, gave evidence which appears to be conclusive that the rosette type of cell first described by Sabin and co-workers, Cunningham and Doan, arises from the reticulo-endothelium of the lymph nodes, while the hyaline type, since it so frequently contains carbon after the intravenous injection of ink, was regarded as a cell derived from the blood vascular endothelium. The cell derived from the lymph vessel endothelium, as well as the one derived from the blood vessel endothelium, was found under certain conditions to present neutral red granules scattered irregularly in the cytoplasm; but the diffuse granulation was found especially in the large young cells and in the actively phagocytic ones of lymph node origin.