The phagocytosis of uniform polystyrene latex particles (PLP) by the reticulo endothelial system (RES) in the rabbit.

THERE has been an increased interest in the phagocytic properties of the reticulo-endothelial system (RES), and the significance of phagocytosis by the RES in host defense mechanisms. There are several recent symposia in which the structure and function of the RES has been extensively considered (Halpern, Benacerraf and Delafresnaye, 1957; Heller, 1960a, 1960b). The recent studies on the RES have resulted in a better understanding of the conditions that govern the removal of a variety of colloidal particles from the circulation in different animals. As a consequence of these studies considerable new knowledge concerning the distribution of particles within organs and cells has been obtained. Essentially phagocytosis by RE cells is governed by 2 broad considerations; the physiological condition of the host and the cells of the RES, and the physical and chemical characteristics of the particle that is presented to the RES. Although technically there are many ways to measure phagocytosis by the RES, all the procedures are variants of 2 methods; measuring the clearance of colloidal particles from the circulation, and location of the colloid in the various organs and within cells. Despite the many investigations of phagocytosis by the RES, little information is available on the clearance from the circulation and on the organ and cellular distribution of suspensions of metabolically inert colloidal particles of known size and shape. This report deals with the phagocytosis of uniform polystyrene latex particles (PLP). The study is divided into 2 phases; the clearance of PLP from the circulation as a function of particle size, dose and repeated challenge, and the organ and intracellular distribution of PLP.