The differentiation of two distinct types of phagocytic cells in the spleen of the rabbit.

Abstract

It has come to be the accepted opinion that the phagocytic cells of the tissues, which have been designated as clasmatocytes, macrophages or histiocytes, and the large mononuclear elements of the blood, the so-called monocytes or transitionals, are cells which are very closely related if not identical. The majority of observers consider them to be derivatives of the reticulo-endothelial apparatus or of endothelial cells in general; indeed one of us (Sabin 1 ) has presented the view that they are identical cells derived from endothelium. A few observers have maintained that there are differences in the two types but even they accept a common ancestry from endothelium or from a hypothetical histiogenic stem-cell. Many observers have noted the great abundance of phagocytic cells in the spleen and have assumed that the spleen is especially favorable for their production.

With this concept in mind, we have studied the living cells which can be obtained from the spleen by puncture and have come to the conclusion, that, however difficult it may be to establish criteria for two distinct types of phagocytic cells in fixed tissues, in living material definite and satisfactory criteria can be established for separating these cells into two distinct types.

The spleen of an anesthetized rabbit was exposed, a capillary pipette plunged into the substance of the organ, and the blood and tissue cells thus obtained were studied in supra-vital films. The stain used for this study was a combination of neutral red and Janus green. 2 With this technique, it soon became apparent that in addition to the lymphocytic and leucocytic strains of white cells which were always present, the remaining cells could be sharply differentiated into two groups. One group consisted of cells to which the names clasmatocyte, macrophage and histiocyte have been applied.